JP7655739B2 - Method for producing fluorine-containing sulfonic acid anhydride - Google Patents

Description

The present invention relates to a method for producing a fluorine-containing sulfonic acid anhydride.

Fluorine-containing sulfonic acid anhydrides have conventionally been useful as catalysts for pharmaceuticals and organic synthesis, or as synthetic raw materials.
As a method for producing a fluorine-containing sulfonic anhydride, for example, a method is known in which diphosphorus pentoxide is added to trifluoromethanesulfonic acid, a dehydration condensation reaction is carried out to produce trifluoromethanesulfonic anhydride, and the produced trifluoromethanesulfonic anhydride is volatilized and recovered.
However, metaphosphoric acid (a reaction product of diphosphorus pentoxide and water) produced as a by-product in the dehydration condensation reaction is glassy and has an extremely high viscosity, and a mixture containing trifluoromethanesulfonic acid and diphosphorus pentoxide becomes unstirable during the reaction (hereinafter, the phenomenon in which a mixture containing trifluoromethanesulfonic acid and diphosphorus pentoxide becomes unstirable during the reaction is referred to as "caking"). As a result, the reaction does not proceed and the produced trifluoromethanesulfonic anhydride cannot be recovered by heating. It is known that the yield of trifluoromethanesulfonic anhydride is at most 60% or less on a trifluoromethanesulfonic acid basis (Patent Documents 1 to 7).

Japanese Patent Application Publication No. 2-268148 Japanese Patent Application Publication No. 9-227498 Japanese Patent Application Publication No. 10-114734 JP 2007-145815 A JP 2007-297359 A JP 2013-112670 A JP 2016-47861 A

Patent Document 1 discloses a production method in which water or phosphoric acid is added to the solidified reaction product of trifluoromethanesulfonic acid and diphosphorus pentoxide to dissolve the metaphosphoric acid, and the reactor is allowed to be stirred, and then vacuum distillation is performed again to recover unreacted trifluoromethanesulfonic acid, thereby increasing the yield of trifluoromethanesulfonic anhydride based on the reacted trifluoromethanesulfonic acid. However, this method does not prevent the reaction product of trifluoromethanesulfonic acid and diphosphorus pentoxide from solidifying. In addition, this method requires the addition of water or phosphoric acid little by little to prevent a sudden increase in temperature due to reaction heat, and stirring cannot be performed until it is dissolved. Therefore, it is necessary to wait a long time until the metaphosphoric acid is completely dissolved in the added water or phosphoric acid, and from an industrial point of view, it is not necessarily a productive process.

Patent Document 2 and Patent Document 3 disclose a production method in which the reaction of trifluoromethanesulfonic acid with diphosphorus pentoxide is carried out in a fluorine-based solvent, thereby suppressing caking. However, because a large amount of solvent is required to suppress caking, it is not necessarily a productive process from an industrial point of view. From a similar point of view, it is desirable to reuse the fluorine solvent used, but an additional step is required to reuse it, which is thought to make the process complicated.

Patent Document 4 discloses a manufacturing method in which caking is suppressed in the reaction between trifluoromethanesulfonic acid and diphosphorus pentoxide by using an excess amount of trifluoromethanesulfonic acid relative to diphosphorus pentoxide. However, although it is desirable from an industrial point of view to reuse the raw material trifluoromethanesulfonic acid, an additional step is required for reuse, which is thought to complicate the process.

Patent Documents 5 to 7 disclose a production method in which the reaction between trifluoromethanesulfonic acid and diphosphorus pentoxide is carried out using a kneader-type reactor equipped with twin-shaft blades having a specified power per volume of the reaction vessel, thereby forcibly kneading the mixture even in a solidified state caused by metaphosphoric acid. However, this requires the use of a special device, a kneader-type reactor equipped with twin-shaft blades having a specified power per volume of the reaction vessel, and there is a demand for a production method that can suppress solidification in a simpler way.

As a result of intensive research aimed at solving the above-mentioned problems, the present inventors discovered that by reacting fluorine-containing sulfonic acid (1) (hereinafter also referred to as "compound (1)") with diphosphorus pentoxide in the presence of alumina, it is possible to suppress caking and produce fluorine-containing sulfonic acid anhydride (2) (hereinafter also referred to as "compound (2).", and thus completed the present invention.

That is, the present invention is as follows.
[1]
The following general formula (2):
(R ^f SO ₂ ) ₂ O (2)
₍ In the formula, ^Rf is a saturated or unsaturated aliphatic hydrocarbon group, and when the hydrocarbon group has -CH2- , _the -CH2- may be substituted with a structure having an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom, and all of the hydrogen atoms in the hydrocarbon group other than the hydrogen atoms of the substituted -CH2- _are substituted with fluorine atoms, the number of carbon atoms in ^Rf is 1 to 20, and the two ^Rfs may be the same or different.)
The present invention relates to a method for producing a fluorine-containing sulfonic acid anhydride (2) represented by the following formula:
The following general formula (1):
R ^f SO ₃ H (1)
(In the formula, R ^f is a saturated or unsaturated aliphatic hydrocarbon group, and when the hydrocarbon group has -CH ₂ - , the -CH ₂ - may be substituted with a structure having an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom, and all of the hydrogen atoms in the hydrocarbon group other than the hydrogen atoms of the substituted -CH ₂ - are substituted with fluorine atoms, and R ^f has 1 to 20 carbon atoms.)
A fluorine-containing sulfonic acid (1) represented by the formula:
Diphosphorus pentaoxide and
A production method, characterized in that the reaction is carried out in the coexistence of alumina.
[2]
The production method according to [1], wherein the ratio (β/α) of the amount of substance (β) (unit: mmol) of diphosphorus pentoxide to the amount of substance (α) (unit: mmol) of the fluorinated sulfonic acid (1) is 0.1 to 100.
[3]
The production method according to [1] or [2], wherein the ratio (ε/(γ+δ)) of the mass (ε) (unit: g) of alumina to the total mass (γ+δ) (unit: g) of the mass (γ) (unit: g) of the fluorine-containing sulfonic acid (1) and the mass (δ) (unit: g) of diphosphorus pentoxide is 0.1 to 100.
[4]
The method according to any one of [1] to [3], wherein the reaction temperature is −40 to 300° C.

According to the present invention, it is possible to suppress solidification during the reaction of fluorine-containing sulfonic acid (1) with diphosphorus pentoxide, and to produce fluorine-containing sulfonic acid anhydride (2) with good yield.

The following provides a detailed description of the embodiment of the present invention (hereinafter, referred to as the "present embodiment"). However, the present invention is not limited to the present embodiment, and can be modified in various ways within the scope of the gist of the present invention.

The manufacturing method of this embodiment is as follows:
The following general formula (2):
(R ^f SO ₂ ) ₂ O (2)
(In the formula, ^Rf is a saturated or unsaturated aliphatic or aromatic hydrocarbon group in which at least one hydrogen atom is substituted with a fluorine atom, and the ethylene structure in the hydrocarbon group may be substituted with a structure having an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom, ^Rf has a carbon number of 1 to 20, and two ^Rfs may be the same or different.)
The present invention relates to a method for producing a fluorine-containing sulfonic acid anhydride (2) represented by the following formula:
The following general formula (1):
R ^f SO ₃ H (1)
(In the formula, ^Rf is a saturated or unsaturated aliphatic or aromatic hydrocarbon group in which at least one hydrogen atom is substituted with a fluorine atom, and the ethylene structure in the hydrocarbon group may be substituted with a structure having an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom, and the number of carbon atoms in ^Rf is 1 to 20.)
A fluorine-containing sulfonic acid (1) represented by the formula:
Diphosphorus pentaoxide and
The reaction is characterized by being carried out in the presence of alumina.

Details of compound (1), alumina, and reaction conditions for producing compound (2) from compound (1) are described below.

<Fluorine-containing sulfonic acid (1) (compound (1))>
The fluorine-containing sulfonic acid (1) is represented by the following general formula (1):
R ^f SO ₃ H (1)
(In the formula, ^Rf is a saturated or unsaturated aliphatic or aromatic hydrocarbon group in which at least one hydrogen atom is substituted with a fluorine atom, and the ethylene structure in the hydrocarbon group may be substituted with a structure having an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom, and the number of carbon atoms in ^Rf is 1 to 20.)
It is expressed as:
The fluorine-containing sulfonic acids (1) may be used alone or in combination of two or more kinds.

As described below, ^Rf is a saturated or unsaturated aliphatic or aromatic hydrocarbon group in which a hydrogen atom is substituted with a fluorine atom. As described below, ^Rf may be at least one hydrocarbon group selected from the group consisting of saturated aliphatic, unsaturated aliphatic, and aromatic groups in which a hydrogen atom is substituted with a fluorine atom. A saturated or unsaturated aliphatic hydrocarbon is preferred because it is easily available or produced and tends to be economical.

The substituent of the hydrogen atom of the hydrocarbon group of ^Rf is not particularly limited so long as it is a commonly used substituent, and specific examples include halogen atoms such as fluorine atom, chlorine atom, bromine atom, etc.; aliphatic hydrocarbon groups such as nitrile group, methyl group, ethyl group, vinyl group, allyl group, 1-methylvinyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, fluoromethyl group, etc.; aromatic hydrocarbon groups such as benzyl group, phenyl group, nitrile-substituted phenyl group, fluorinated phenyl group, etc.; groups having a structure in which the aliphatic hydrocarbon group and aromatic hydrocarbon group are fluorinated; amino group, nitro group, sulfo group, hydroxyl group, silyl group, phosphate group, thiol group, etc. These substituents may be used alone or in combination of two or more types.

When the hydrocarbon group of ^Rf has an aliphatic portion, the ethylene structure (-CH ₂ -) of the hydrocarbon group may be substituted with a structure having an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom, or may be substituted with a structure having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom and a silicon atom.
The structure with which the ethylene structure (-CH ₂ -) of the hydrocarbon group in ^Rf is substituted is not particularly limited so long as it is a commonly used structure, but may be a divalent structure, and specific examples include an ether group (-O-), a carbonate group (-OCO ₂ -), an ester group (-CO ₂ -), a carbonyl group (-CO-), a sulfide group (-S-), a sulfoxide group (-SO-), a sulfone group (-SO ₂ -), a urethane group (-NHCO ₂ -), etc. These substituents may be used alone or in combination.

The number of carbon atoms in ^Rf is not particularly limited as long as it is a commonly used carbon number; however, because Rf is easily available or produced and tends to be economically advantageous, it is preferably 1 to 20, more preferably 1 to 10, even more preferably 1 to 7, and particularly preferably 1 to 5.

The number of fluorine atoms resulting from the substitution of hydrogen atoms in ^Rf (the number of hydrogen atoms in the hydrocarbon group substituted with fluorine atoms) is not particularly limited as long as it is 1 or more, but is preferably 3 or more. Depending on the type of compound (1), it is more preferably 5 or more, and even more preferably 7 or more. When high durability of compound (1) and/or compound (2) is required, it is particularly preferable that all hydrogen atoms in the aliphatic or aromatic hydrocarbon group are fluorine atoms.

The number of substituted ethylene structures in ^Rf (the number of ethylene structures substituted with a structure having an oxygen atom or the like) may be 0 to 10, more preferably 0 to 7, and further preferably 0 to 5.

（式中、ｍは０～３の整数、ｎは１～６の整数）
で表される含フッ素ビニルスルホン酸（３）であることが特に好ましい。 In this embodiment, the compound (1) is represented by the following general formula (3):

(wherein m is an integer from 0 to 3, and n is an integer from 1 to 6).
Particularly preferred is a fluorine-containing vinyl sulfonic acid (3) represented by the following formula:

As m, 0 to 1 is preferable, and 0 is more preferable, since it is easily available or produced and tends to be economical.
As n, it is preferable that n is 1 to 4, more preferably 2 to 4, and even more preferably 2, because n is easily available or produced and tends to be economical.
A particularly preferred combination of m and n is m=0 and n=2.

（式中、ｍは０～３の整数、ｎは１～６の整数）
で表される。 The structure of the compound (2) produced from the above-mentioned fluorine-containing vinyl sulfonic acid (3) is represented by the following general formula (4):

(wherein m is an integer from 0 to 3, and n is an integer from 1 to 6).
It is expressed as:

m and n are the same as in compound (3), and m is preferably 0 to 1, and more preferably 0, since it is easily available or produced and tends to be economical.
As n, it is preferable that n is 1 to 4, more preferably 2 to 4, and even more preferably 2, because n is easily available or produced and tends to be economical.
A particularly preferred combination of m and n is m=0 and n=2.

Fluorine-containing sulfonic acid (1) can be produced by a conventional method or purchased.

<Diphosphorus pentoxide>
Diphosphorus pentoxide is a compound with _the chemical formula _P2O5 . However, _its actual structure has the chemical formula _P4O10 , and it is also known as tetraphosphorus decaoxide. It is also commonly called phosphorus oxide, phosphorus pentoxide, and phosphoric anhydride.

The purity of diphosphorus pentoxide is not particularly limited as long as it is a generally available purity, but since this tends to suppress side reactions and improve the yield of compound (2), it is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, and particularly preferably 98% by mass or more.

Diphosphorus pentoxide of the desired purity can be purchased from Fujifilm Wako Pure Chemical Industries, Ltd., Tokyo Chemical Industry Co., Ltd., Aldrich Corporation, Nacalai Tesque Inc., Kanto Chemical Co., Ltd., Nippon Chemical Industry Co., Ltd., Rasa Kogyo Co., Ltd., etc.

<Alumina>
In the present embodiment, alumina refers to a compound containing 50% by mass or more of aluminum oxide (Al ₂ O ₃ ). The amount of aluminum oxide contained in alumina is preferably 70% by mass or more, more preferably 90% by mass or more, even more preferably 97% by mass or more, and particularly preferably 99% by mass or more, because side reactions can be suppressed and the yield of compound (2) tends to be improved.

Alumina is known to have α, γ, η, δ, ρ, κ, θ, χ, and α type crystal phases, but since they are generally easy to obtain, tend to be economical, and tend to be highly stable, α, γ, and θ type crystal phases are preferred, α and γ type crystal phases are more preferred, and α type crystal phase is even more preferred.

The shape of the alumina is not particularly limited as long as it is a commonly available shape, and may be any of spherical, spindle-shaped, rod-shaped, needle-shaped, cylindrical, columnar, scaly, thin, and plate-shaped. If this viewpoint is emphasized, spherical shapes are preferred because they tend to improve the fluidity of the mixture of compound (1), diphosphorus pentoxide, and alumina, and the mixture during the reaction, and because the shape tends to be highly stable in the fluid state. If this viewpoint is emphasized, alumina with a mixture of various shapes is preferred because they tend to be easily available and economically superior.

In this embodiment, the particle size refers to a cumulative average diameter measured by a particle size distribution measuring device (the particle size at the point where the cumulative curve is 50% when the total volume of the powder population to be analyzed is taken as 100%).
The particle size of the alumina is not particularly limited as long as it is a generally available particle size, but it is preferably 0.01 to 1000 μm.
Since there is a tendency for caking to be suppressed, the particle size of the alumina is preferably 1000 μm or less, more preferably 150 μm or less, further preferably 70 μm or less, and particularly preferably 40 μm or less.
The particle size of alumina is preferably 0.01 μm or more, more preferably 0.1 μm or more, since it tends to be easy to obtain or produce and is economically superior. The particle size of alumina is further preferably 0.5 μm or more, particularly preferably 1 μm or more, since the bulk density of alumina increases, the capacity of the device used in producing compound (2) tends to be small, and the cost of the device tends to be low.

In the present embodiment, the calculated specific surface area of alumina obtained by particle size analysis is not particularly limited as long as it is the calculated specific surface area of alumina that is generally available, but since it tends to suppress caking, it is preferably 0.01 m ² /mL or more, more preferably 0.05 m ² /mL or more, even more preferably 0.50 m ² /mL or more, and particularly preferably 0.80 m ² /mL or more. Since it tends to be easy to obtain or produce and has excellent economical properties, and the bulk density of alumina increases, the capacity of the device used in producing compound (2) tends to be small, and the cost of the device tends to be low, it is preferably 100 m ² /mL or less, more preferably 50 m ² /mL or less, even more preferably 10 m ² /mL or less, and particularly preferably 6.0 m ² /mL or less.
The calculated specific surface area is a value calculated by the following formula (1) using the area average diameter obtained by a particle size distribution analyzer.
Calculated specific surface area (m ² /mL) = 6÷Area average diameter (μm) (1)

The alumina is not particularly limited as long as it is generally available or can be manufactured, but specific examples include the SA series, A series, SMM series, MM series, AN series, LS series, and AHP series manufactured by Nippon Light Metal Co., Ltd., the FA series, RW series, CB series, and AS series manufactured by Showa Denko K.K., and the A series, AM series, AL series, ALM series, AMS series, AES series, AKP series, AA series, HIT series, and AKX series manufactured by Sumitomo Chemical Co., Ltd. These include the CA series, SA series, KES series, KAM series, and KLS series manufactured by Rasa Shoji Co., Ltd., the AO series manufactured by Admatechs Co., Ltd., the CR series manufactured by Baikowski Japan Co., Ltd., the Taimicron series manufactured by Taimei Chemical Industry Co., Ltd., the N series and R series manufactured by Nishimura Porcelain Co., Ltd., aluminum oxide, alumina, and α-alumina manufactured by Aldrich, aluminum oxide and α-alumina manufactured by Fuji Film Wako Pure Chemical Industries Co., Ltd., and aluminum oxide and alumina manufactured by Kanto Chemical Co., Ltd.

Alumina having a desired particle size can be produced by crushing available alumina. The crushing method is not particularly limited as long as it is a commonly used method, and may be wet or dry, and examples of the crushing device include a jaw crusher, a gyration trial crusher, a cone crusher, an impact crusher, a rod mill, a hammer crusher, a roll crusher, a cutter mill, an autogenous crusher, a stamp mill, a stone mill, a crushing machine, a ring mill, a roller mill, a jet mill, a pin mill, a rotary mill, a vibration mill, a planetary mill, an attritor, a bead mill, etc. These devices may be used alone or in combination of two or more types.
More specific examples of grinding devices include Nibbler, Feather Mill, Pharma Mill, Hammer Mill, Hammer Blade, Disintegrator, Rubber Chopper, Rotoplex, Compact Line, ACM Pulverizer, Glacis, Fine Impact Mill, Victory Mill, Contraplex, Linrex Mill, Micro Pulverizer, Counter Jet Mill, Micron Jet, Super Micron Mill, Innomizer, Pulvis, Spiral Jet Mill, Disper Mill, and Hydro Mill, all manufactured by Hosokawa Micron Corporation; Jiyu Pulverizer, New Cosmomizer, Micros, Super Clean Mill, Sample Mill, Super Jiyu Mill, Mill Box, Cosmo Box, Hammer Mill, Goblin, Baryonyx, Briodon, Polvogene, and Gina, all manufactured by Kurimoto Iron Works, Ltd.; and Cross Jet Mill, Pocket Jet, Gadget, Ha Izzy, agitator mill, VX mill, roller mill, ball mill, rod mill, K-VIX mill, and granulator; jaw crusher, ratchet roll crusher, corrugated roll crusher, roll crusher, tandem roll crusher, Oniha roll crusher, S-shaped crusher, 4-axis crusher, fiber mill, bevel impactor, radical impactor, ball mill, attrition mill, and cube rotor mill manufactured by Sugiyama Heavy Industries Co., Ltd.; super powder mill, fairy powder mill, stamp mill, high-speed crusher, hammer crusher, sloot mill, Seryuner, shredder, and cutter mill manufactured by Nishimura Machinery Works Co., Ltd.; vertical roller mill, Kryptron Zepros, Kryptron Venti, Kryptron, Kryptron Eddy, Kryptron Prime, Jedi, Converge Mill, Oshlobit, Co., Ltd. manufactured by EarthTechnica Co., Ltd. Nibit and hammer mill, Super Jet Mill, Super Rotor and Blade Mill manufactured by Nisshin Engineering Inc., Dry Star, Sigma Dry, Lab Star, Nano Getter, Mugen Flow and Delta Vita manufactured by Ashizawa Finetech Co., Ltd., Single Track Jet Mill, Sk Jet O Mill, Cojet System α-mkV, Sanitary JOM Series, A-O Jet Mill, Impeller Mill, Planetary Mill, Orient Crusher, Atomizer, Pin Mill and Spiral Mill manufactured by Seishin Enterprise Co., Ltd., Frame Dismantling Machine, Oniha Crusher, Tear Crusher, Hammer Crusher, Makino Type Crusher, Exceed Mill, Disc Type Crusher, Coroplex Type Crusher, Contraplex Type Crusher and Ultraplex Type Crusher manufactured by Tsukasa Kogyo Co., Ltd. Mill, Wave Mill, and Powjet; Easy Nano, Ready Mill, Neo-Alpha Mill, low-temperature/frozen grinding bead mill, Visco Mill, and sand grinder manufactured by Imex Co., Ltd.; Apex Mill, Ultra Apex Mill, Wide Separator Apex Mill, Dual Apex Mill, Ultra Apex Mill Advance, Apex Disperser ZERO, and Apex LABO manufactured by Hiroshima Metal & Machinery Co., Ltd.; MSC Mill, SC Mill, SC Mill Long, MY Mill, Attritor, Trigonal, Fine Mill, Dynamic Mill, Alchemy, Stream Mill, and Centri Cutter manufactured by Nippon Coke & Engineering Co., Ltd.; Mighty Mill Mark II, Spike Mill, Key Mill, MP Mill, MF Mill, Mighty Mill, Nano Sonic Mill, 3-roll mill ceramic roll, and 3-roll mill chilled roll manufactured by Inoue Seisakusho Co., Ltd.

The alumina may be surface-modified as necessary. The surface-modified alumina may be a commonly available alumina, or may have been subjected to a surface modification treatment. The compound used for surface modification is not particularly limited as long as it is a commonly used compound, but examples of compounds that tend to have excellent adsorption ability to alumina include organic acids such as organic sulfonic acids, organic phosphoric acids, organic phosphoric acid esters, and carboxylic acids, and alkoxysilane compounds (compounds also known as silane coupling agents). More specific examples of organic acids include methanesulfonic acid, ethanesulfonic acid, octane sulfonic acid, dodecanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, dimethylbenzenesulfonic acid, biphenylsulfonic acid, styrenesulfonic acid, decylbenzenesulfonic acid, undecylbenzenesulfonic acid, dodecylbenzenesulfonic acid, tridecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, naphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, naphthalenedisulfonic acid, anthracenesulfonic acid, phenanthrenesulfonic acid, tributyl phosphate, diethyl phosphate, methyl phosphate, butoxyethyl phosphate, bis(butoxyethyl)phosphate, dibutyl phosphate, dihexyl phosphate, triphenyl phosphate, phenyl phosphate, dimethylphenyl phosphate, naphthyl phosphate, dimethylphosphonate ... dibutyl phosphate, dihexyl phosphate, triphenyl phosphate, phenyl phosphate, dimethylphenyl phosphate, naphthyl phosphate, dimethylphosphonate, tributyl phosphate, diethyl phosphate, methyl phosphate, butoxyethyl phosphate, dibutyl phosphate, dihexyl phosphate, triphenyl phosphate, phenyl phosphate, dimethylphenyl phosphate, naphthyl phosphate, dimethylphosphonate, tributyl phosphate, diethyl phosphate, methyl phosphate, butoxy tributyl phosphite, triphenyl phosphite, triphenylphosphine oxide, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phosphonic acids such as methyl phosphonic acid, ethyl phosphonic acid, octyl phosphonic acid, dodecyl phosphonic acid, phenyl phosphonic acid, octyl phenyl phosphonic acid, dodecyl phenyl phosphonic acid, naphthalene phosphonic acid, anthracene phosphonic acid, and phenanthrene phosphonic acid; alkyl carboxylic acids such as methyl phosphinic acid, ethyl phosphinic acid, phenyl phosphinic acid, diphenyl phosphinic acid, acetic acid, caproic acid, caprylic acid, capric acid, lauric acid, and stearic acid; benzoic acid, toluic acid, dodecyl benzoic acid, methoxybenzoic acid, phenoxybenzoic acid, naphthalene carboxylic acid, phthalic acid, salicylic acid, dodecyl benzoic acid, anthracene carboxylic acid, phenanthrene carboxylic acid, lactic acid, malic acid, and adipic acid. Examples of alkoxysilane compounds include alkylalkoxysilanes such as methyltrimethoxysilane, ethyltrimethoxysilane, butyltrimethoxysilane, and octyltrimethoxysilane, epoxyalkoxysilanes such as γ-glycidoxypropyltriethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, aminoalkoxysilanes such as aminopropyltriethoxysilane and N-phenylaminopropyltrimethoxysilane, vinylalkoxysilanes such as vinyltrimethoxysilane and vinyltriethoxysilane, and acrylicalkoxysilanes such as acryloxytrimethoxysilane and acrylomethoxytriethoxysilane. The compounds used for surface modification may be used alone or in combination.

Alumina may be used alone or in combination with multiple types.

When compound (1) is reacted with diphosphorus pentoxide in the presence of alumina, additives such as ether compounds, nitrile compounds, amide compounds, sulfo compounds, saturated hydrocarbon compounds, aromatic hydrocarbon compounds, halogenated hydrocarbon compounds, ketone compounds, ester compounds, and fluorine compounds can be used as necessary.

The additive is not particularly limited as long as it is a commonly used compound, and specific examples thereof include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 4-methyltetrahydropyran, cyclopentyl methyl ether, diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, methyl tert-butyl ether, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethylene glycol dibutyl ether, 1,2-dimethoxypropane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol isopropyl methyl ether, and diethylene glycol butyl methyl ether. ether compounds such as ethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, and dipropylene glycol dimethyl ether; nitrile compounds such as acetonitrile, propionitrile, butyronitrile, isobutyronitrile, 2-methylbutyronitrile, cyclohexanecarbonitrile, benzonitrile, and adiponitrile; amide compounds such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methylpyrrolidone, tetramethylurea, and 1,3-dimethyl-2-imidazolidinone; dimethyl sulfoxide, dibutyl sulfoxide, ethyl methyl sulfone, ethyl isopropyl sulfone, and the like. sulfo compounds such as hexane, sulfolane, and 3-methylsulfolane; saturated hydrocarbon compounds such as n-pentane, n-hexane, isohexane, n-heptane, n-octane, isooctane, n-nonane, n-decane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane; aromatic hydrocarbon compounds such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, naphthalene, tetralin, and biphenyl; methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, trichloroethane, tetrachloroethane, pentachloroethane, hexachloroethane, dichloroethylene, trichloroethylene, tetrachloroethylene, dichloropropane, trichloropropane, isopropyl chloride, butyl chloride, hexyl chloride, chloroform ... halogenated hydrocarbon compounds such as chlorobenzene, dichlorobenzene, trichlorobenzene, chlorotoluene, and chloronaphthalene; ketone compounds such as acetone, methyl acetone, ethyl methyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyl hexyl ketone, diethyl ketone, ethyl butyl ketone, dipropyl ketone, diisobutyl ketone, and cyclohexanone; ester compounds such as ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, hexyl acetate, octyl acetate, cyclohexyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, and benzyl benzoate; fluoroalkylsulfonic anhydrides (C _Examples of fluorine compounds include fluoroalkylsulfonate _{CmF2m +} 1SO2OCnF2n+ ₁ (m=1-10, n= _1-10 ), perfluoroalkane _{CmF2m + 2} (m=4-20), perfluoroalkylamine _{( CmF2m +1} ) _3N ( _m =2-10) _, and perfluoropolyether.

The additives may have a reduced water content, if necessary.
Additives with low water content can be purchased, or a method for reducing the water content of the additive can be used. The method for reducing the water content of the additive is not particularly limited as long as it is a commonly available method, and examples thereof include a method using a dehydrating agent and a distillation method.
The dehydrating agent is not particularly limited as long as it is a commonly used dehydrating agent, and examples thereof include sodium hydride, magnesium sulfate, sodium sulfate, calcium sulfate, calcium chloride, zinc chloride, calcium oxide, magnesium oxide, diphosphorus pentoxide, activated alumina, silica gel, and molecular sieves. When a dehydrating agent is used, an additive containing a dehydrating agent may be used as long as it does not affect the reaction between compound (1) and diphosphorus pentoxide, or an additive that does not contain a dehydrating agent after filtration or the like may be used.

<Ratio (β/α) of the amount of diphosphorus pentoxide (β) to the amount of compound (1) (α)>
In this embodiment, the substance amount of diphosphorus pentoxide is 141.94 g/mol.
The ratio (β/α) of the substance amount (β) of diphosphorus pentoxide to the substance amount (α) of compound (1) tends to be able to suppress the remaining unreacted compound (1), so it is preferably 0.1 or more, more preferably 0.5 or more, even more preferably 1 or more, and particularly preferably 2 or more.
The upper limit of the ratio (β/α) of the amount of substance (β) of diphosphorus pentoxide to the amount of substance (α) of compound (1) is not particularly limited, but since the amount of diphosphorus pentoxide used is reduced and the method for producing compound (2) tends to be more economical, β/α is preferably 100 or less, and more preferably 20 or less. Since the yield of compound (2) tends to increase and the method for producing compound (2) tends to be more economical, β/α is further preferably 10 or less, and particularly preferably 5 or less.

<Ratio (ε/(γ+δ)) of the mass of alumina (ε) to the total mass (γ+δ) of the mass (γ) of compound (1) and the mass (δ) of diphosphorus pentoxide>
The ratio (ε/(γ+δ)) of the mass of alumina (ε) to the total mass (γ+δ) of the mass (γ) of compound (1) and the mass (δ) of diphosphorus pentoxide tends to be able to suppress caking in the reaction between compound (1) and diphosphorus pentoxide, and is therefore preferably 0.1 or more, more preferably 0.25 or more, even more preferably 0.5 or more, and particularly preferably 0.75 or more.
The upper limit of the ratio (ε/(γ+δ)) of the mass of alumina (ε) to the total mass (γ+δ) of the mass (γ) of compound (1) and the mass (δ) of diphosphorus pentoxide is not particularly limited, but since the amount of alumina used is reduced and the method for producing compound (2) tends to be more economical, (ε/(γ+δ)) is preferably 100 or less, and more preferably 10 or less. Since the yield of compound (2) tends to increase and the method for producing compound (2) tends to be more economical, (ε/(γ+δ)) is further preferably 7 or less, and particularly preferably 5 or less.

<Reaction of compound (1) with diphosphorus pentoxide>
The reaction temperature of compound (1) and diphosphorus pentoxide is not particularly limited as long as it is a reaction temperature that is generally used, but since the reactivity of compound (1) and diphosphorus pentoxide tends to be enhanced, the reaction temperature is preferably −40° C. or higher, and more preferably −20° C. or higher. From the same viewpoint and since the reaction temperature tends to be economically advantageous when adjusting the temperature industrially, the reaction temperature is further preferably 0° C. or higher, and particularly preferably 10° C. or higher.
The upper limit of the reaction temperature between compound (1) and diphosphorus pentoxide is not particularly limited, but since volatilization of compound (1) can be suppressed and the stability of the yield of compound (2) tends to be increased, the upper limit is preferably 300° C. or less, and more preferably 250° C. or less. Since deterioration of compound (2) can be suppressed and the economic efficiency of the method for producing compound (2) tends to be increased, the upper limit is further preferably 200° C. or less, and particularly preferably 180° C. or less.
The reaction temperature of compound (1) and diphosphorus pentoxide does not have to be constant so long as it is within the above range, and may be changed during the reaction.

It is presumed that when compound (2) is produced by the reaction of compound (1) with diphosphorus pentoxide, compound (1) reacts with diphosphorus pentoxide to form a reactant, and then compound (2) is produced from the reactant. Therefore, the reaction temperature for forming the reactant and the reaction temperature for producing compound (2) from the reactant may be the same or different.
The reaction temperature when forming the reactant is preferably −40° C. or higher, and more preferably −20° C. or higher, since the reactivity of compound (1) with diphosphorus pentoxide tends to be increased. From the same viewpoint, and since there is a tendency for the temperature to be economically excellent in industrial temperature adjustment, the reaction temperature is more preferably 0° C. or higher, and particularly preferably 10° C. or higher. Since there is a tendency for deterioration of compound (1) due to reaction heat to be suppressed by suppressing the reaction between compound (1) and diphosphorus pentoxide, the reaction temperature is preferably 180° C. or lower, more preferably 150° C. or lower, and even more preferably 120° C. or lower.
The reaction temperature for producing compound (2) from the reactant is preferably 80° C. or higher, more preferably 100° C. or higher, and even more preferably 120° C. or higher, since the production of compound (2) tends to be promoted. The reaction temperature is preferably 300° C. or lower, and more preferably 250° C. or lower, since the stability of the yield of compound (2) tends to be improved. The reaction temperature is more preferably 200° C. or lower, and particularly preferably 180° C. or lower, since the deterioration of compound (2) can be suppressed and the economic efficiency of the method for producing compound (2) tends to be improved.

The reaction time between compound (1) and diphosphorus pentoxide is not particularly limited as long as it is within the range generally used, but since this increases the stability of the yield of compound (2), it is preferably 0.5 hours or more, and more preferably 1 hour or more. Since avoiding an excessive reaction time tends to result in a more economical production method, it is preferably 100 hours or less, and from the same viewpoint, it is more preferably 50 hours or less, and even more preferably 20 hours or less.

The reaction pressure between compound (1) and diphosphorus pentoxide is not particularly limited as long as it is within a range that is usually used, and may be any of pressurized, normal pressure, and reduced pressure. Depending on the type of compound (1), the vapor pressure at the reaction temperature is high, so that reaction under pressurized pressure may be preferable since it tends to suppress the volatilization of compound (1). Depending on the type of compound (1), the vapor pressure at the reaction temperature is low, so that reaction under normal pressure may be preferable since it tends to be more economical. Depending on the type of compound (2), the vapor pressure at the reaction temperature is low, so that when compound (2) is volatilized and recovered, reduced pressure may be preferable. Depending on the type of compound (2), the vapor pressure at the reaction temperature is low, so that reaction under normal pressure may be preferable since it tends to be more economical.
The upper limit of the pressure when applying pressure is not particularly limited as long as it is within a range that is commonly used, but since this tends to reduce the complexity of the pressurizing device, the upper limit is preferably 100 MPaG or less, more preferably 1 MPaG or less, even more preferably 0.4 MPaG or less, and particularly preferably 0.2 MPaG or less.
The lower limit of the pressure when reducing the pressure is not particularly limited as long as it is within a commonly used range. However, since this tends to reduce the complexity of the pressure reducing device, the lower limit is preferably 0.01 PaA or more, more preferably 1 PaA or more, even more preferably 100 PaA or more, and particularly preferably 500 PaA or more.
The pressure in the reaction of compound (1) with diphosphorus pentoxide does not need to be constant so long as it is within the above range, and may be changed during the reaction.

The atmosphere for the reaction of compound (1) with diphosphorus pentoxide is not particularly limited as long as it is a commonly used atmosphere, and typically, air, nitrogen, argon, and the like are used. Among these, nitrogen and argon atmospheres are preferred because they tend to produce compound (2) more safely. In addition, nitrogen atmosphere is more preferred because they tend to be a more economical production method.
The atmospheric dew point of the reaction atmosphere is preferably −10° C. or lower, more preferably −30° C. or lower, and even more preferably −50° C. or lower, since this tends to suppress deterioration of diphosphorus pentoxide.
The reaction atmosphere may be used alone or in combination of a plurality of reaction atmospheres.

As described above, in the reaction between compound (1) and diphosphorus pentoxide, compound (1) reacts with diphosphorus pentoxide to form a reactant, and then compound (2) is produced from the reactant. As a result of detailed observation of this reaction, the present inventors found that the reactant solidifies when it becomes a reactant, and even if the solidified reactant is pulverized, it solidifies again when compound (2) is produced from the reactant. Therefore, by reacting compound (1) with diphosphorus pentoxide to produce a reactant using an apparatus capable of suppressing solidification when it becomes a reactant, and then adding alumina, it is also possible to suppress solidification when compound (2) is produced from the reactant.
That is, alumina may be added when compound (1) is reacted with diphosphorus pentoxide to form a reactant, alumina may be added after compound (1) is reacted with diphosphorus pentoxide to form a reactant, or alumina may be added when compound (1) is reacted with diphosphorus pentoxide to form a reactant, and further alumina may be added after the reactant is formed. Among these, the method of adding alumina when compound (1) is reacted with diphosphorus pentoxide to form a reactant is preferred because it tends to always suppress solidification in the reaction in which compound (1) reacts with diphosphorus pentoxide to produce compound (2) and tends to reduce the complexity of operations during the reaction.
In the method of adding alumina when reacting compound (1) with diphosphorus pentoxide to form a reactant, the order of adding compound (1), diphosphorus pentoxide, and alumina is not particularly limited. However, since there is a tendency that solidification due to the reaction of compound (1) with diphosphorus pentoxide can be further suppressed, preferred examples of the method include a method of adding a mixture of compound (1) and alumina to diphosphorus pentoxide, a method of adding diphosphorus pentoxide to a mixture of compound (1) and alumina, a method of adding a mixture of diphosphorus pentoxide and alumina to compound (1), and a method of adding compound (1) to a mixture of diphosphorus pentoxide and alumina.

The method for mixing compound (1), diphosphorus pentoxide, and alumina is not particularly limited as long as it is a commonly used method, and examples of such a method include a mixing tank type (horizontal type, vertical type), the number of stirring shafts (two shafts, three shafts, four shafts), the shape of a stirring blade (for example, fan, propeller, cross, butterfly, dragonfly, turbine, disk turbine, disperse, paddle, inclined paddle, helical, double helical, ribbon, straight blade, 45° twist blade, 90° twist blade, etc.), and the installation of a baffle in a mixing tank.
More specifically, examples of mixing devices include the pressure kneader, Wonder kneader, kneading test device Mix Lab, small-volume pressure kneader, MS-type small pressure kneader, twin-arm kneader, valve kneader, kneader ruder, special pressure kneader, reduced pressure kneader, twin-screw taper extruder, twin-screw single-screw extruder, and feeder ruder manufactured by Nihon Spindle Mfg. Co., Ltd.; the KRC kneader, batch kneader, pressure kneader, extruder, CD dryer, SC processor, and CD dryer manufactured by Kurimoto Iron Works, Ltd.; BDM twin-shaft mixer, butterfly mixer, CDM concentric twin-shaft mixer, pony mixer, trimix, planetary mixer, PD mixer, kneader, flushing kneader, salt milling kneader, pressure kneader, and KX kneader manufactured by Kamiseisakusho Co., Ltd.; Pam Apex mixer, Super Double Mixer manufactured by Pacific Machinery Co., Ltd.; vertical mixer, ribbon mixer, high-speed paddle mixer, and paddle mixer manufactured by Nishimura Machinery Co., Ltd.; Byte Mix, Nauta Mixer, Solid Air, Micron Thermo Processor, and Torus Disk manufactured by Hosokawa Micron Co., Ltd.; paddle dryer, single paddle dryer, Buno Cooler, multi-fin processor, extruder, and high-speed mixing and granulating machine manufactured by Nara Machinery Co., Ltd.; PV mixer and SV mixer manufactured by Kobelco Eco-Solutions Co., Ltd.; Ribo Cone and Flow Jet Granulator manufactured by Okawara Manufacturing Co., Ltd.; twin-shaft kneading extruder manufactured by The Japan Steel Works, Ltd.; Hivis Mix, Hivis Disper Mix, and Combi Mix manufactured by Primix Corporation. , the ACM series manufactured by Aikosha Seisakusho Co., Ltd., the mixer, twin servo mixer, S kneader, spherical kneader, spherical beveled axis kneader, and high-speed kneading granulator manufactured by Shinagawa Kogyosho Co., Ltd., the intensive mixer and Evactherm manufactured by Nippon Eirich Co., Ltd., the axial mixer and Hemisphere mixer manufactured by Sugiyama Heavy Industries Co., Ltd., a vacuum mixer dryer manufactured by Katsuragi Kogyo Co., Ltd., a vacuum mixer dryer manufactured by Yasujima Co., Ltd., a mixer, semi-pressure kneader, kneader ruder, and vacuum extruder manufactured by MIG Co., Ltd., and the like.
In the case where a large amount of alumina is used or where alumina is added to the pulverized reaction product to produce compound (2), in addition to the above-mentioned apparatuses, examples of the apparatus include a KID dryer, a rotoluba dryer, a rotary dryer, and a rotary kiln manufactured by Kurimoto Iron Works, Ltd., a conical dryer manufactured by Kobelco Eco-Solutions Co., Ltd., an electrically heated rotary kiln, a gas heated rotary kiln, a batch type rotary kiln, a desktop rotary kiln, a vacuum desktop rotary kiln, and a special atmosphere + vacuum rotary kiln manufactured by Takasago Industrial Co., Ltd., a super rotary dryer and an eco dryer manufactured by Okawara Manufacturing Co., Ltd., a rotary kiln and a double cone mixer manufactured by Sugiyama Heavy Industries Co., Ltd., a double cone dryer manufactured by Katsuragi Kogyo Co., Ltd., and a rotary kiln manufactured by Yasujima Corporation.

In the case where compound (1), diphosphorus pentoxide, and alumina are not mixed at the same time, but any of the combinations of compound (1) and diphosphorus pentoxide, compound (1) and alumina, and diphosphorus pentoxide and alumina is mixed before being supplied to an apparatus for mixing compound (1), diphosphorus pentoxide, and alumina, in addition to the above-mentioned apparatus, a Nibbler, Feather Mill, Farma Mill, Hammer Mill, Hammer Blade, Disintegrator, Rubber Chopper, Rotoplex, Compact Line, ACM Pulverizer, Glacis, Fine Impact Mill, Victory Mill, Contraplex, Rinrex Mill, Micro Pulverizer, Counter Jet Mill, Micron Jet, Super Micron Mill, Innomizer, Pulvis, Spiral Jet Mill, Disper Mill, and Hydro Mill manufactured by Nara Machinery Manufacturing Co., Ltd., and a Free Grinding Mill, New Cosmomizer, Micros, Super Clean Mill, and Sample Mill manufactured by Nara Machinery Manufacturing Co., Ltd. may be used. , Super Jiyu Mill, Mill Box, Cosmo Box, Hammer Mill, Goblin, Baryonyx, Briodon, Polvogene, and Gina, Cross Jet Mill, Pocket Jet, Gadget, Hi-G, Agitator Mill, VX Mill, Roller Mill, Ball Mill, Rod Mill, K-VIX Mill, and Granulator manufactured by Kurimoto Iron Works, Ltd., Jaw Crusher, Ratchet Roll Crusher, Corrugated Roll Crusher, Roll Crusher, Tandem Roll Crusher, Oniha Roll Crusher, S-Shaped Crusher, 4-Axis Crusher, Fiber Mill, Bevel Impactor, Radical Impactor, Ball Mill, Attrition Mill, and Cube Rotor Mill manufactured by Sugiyama Heavy Industries, Ltd., Super Powder Mill, Fairy Powder Mill, Stamp Mill, High Speed Crusher, Hammer Crusher, Sloot Mill, Seryuner, Shredder, and Cutter Mill manufactured by Nishimura Machinery Works, Ltd., Vertical Roller Mill, Cryptron Ze Pros, Kryptron Venti, Kryptron, Kryptron Eddy, Kryptron Prime, Jedi, Converge Mill, Oshlobit, Conibit, and Hammer Mill, Super Jet Mill, Super Rotor, and Blade Mill manufactured by Nisshin Engineering Inc., Dry Star, Sigma Dry, Lab Star, Nano Getter, Mugen Flow, and Delta Vita manufactured by Ashizawa Finetech Co., Ltd., Single Track Jet Mill, Sk Jet-O-Mill, Cojet System α-mkV, Sanitary JOM Series, A-O Jet Mill, Impeller Mill, Planetary Mill, Orient Crusher, Atomizer, Pin Mill, and Spiral Mill manufactured by Seishin Enterprise Co., Ltd., Frame Dismantling Machine, Oniha Crusher, Tear Crusher, Hammer Crusher, Makino Type Crusher, Exceed Mill, Disc Type Crusher, Coroplex Type Crusher, Contraplex Type Crusher, and Ultraplex Type Powder Mill manufactured by Makino Sangyo Co., Ltd. Examples of the crusher include Powcutter, Powcrusher, Line Mill, Wave Mill, and Powjet manufactured by Tsukasa Kogyo Co., Ltd., Easy Nano, Ready Mill, Neo-Alpha Mill, low-temperature/frozen grinding bead mill, Visco Mill, and sand grinder manufactured by Imex Co., Ltd., Apex Mill, Ultra Apex Mill, Wide Separator Apex Mill, Dual Apex Mill, Ultra Apex Mill Advance, Apex Disperser ZERO, and Apex LABO manufactured by Hiroshima Metal & Machinery Co., Ltd., MSC Mill, SC Mill, SC Mill Long, MY Mill, Attritor, Trigonal, Fine Mill, Dynamic Mill, Alchemy, Stream Mill, and Centri Cutter manufactured by Nippon Coke & Engineering Co., Ltd., and Mighty Mill Mark II, Spike Mill, Key Mill, MP Mill, MF Mill, Mighty Mill, Nano Sonic Mill, Three-roll Mill Ceramic Roll, and Three-roll Mill Chilled Roll manufactured by Inoue Seisakusho Co., Ltd.
The mixing device may be used alone or in combination of a plurality of types of mixing devices.

Methods for adding compound (1) to an apparatus for mixing compound (1), diphosphorus pentoxide, and alumina include adding compound (1) using its own weight, adding compound (1) under pressure, and adding compound (1) using a liquid delivery pump (e.g., a smooth flow pump, a motor-driven metering pump, a solenoid-driven metering pump, an air-driven pump, a dynamic vacuum pump, a tube pump, a slurry pump, a magnet pump, an air-driven bellows pump, an electromagnetically-driven metering pump, a rotary volumetric pump, etc.). The method using a liquid delivery pump is preferred because it tends to provide excellent control over the rate at which compound (1) is added.

Examples of methods for adding diphosphorus pentoxide and/or alumina to a device for mixing compound (1), diphosphorus pentoxide, and alumina include a method of adding by using its own weight, a method of adding by circulating an air current (e.g., suction-type pneumatic transport, low-pressure pressure-fed pneumatic transport, high-pressure pressure-fed organic transport, etc., and the pneumatic transport may be transport in a different atmosphere such as dry air transport, nitrogen transport, and argon transport), and a method of adding by using a powder feeder (e.g., a screw feeder, a vibration feeder, a circle feeder, a conveyor-type feeder, an auger-type powder filling machine, a weighing-type powder feeder, a volumetric-type powder feeder, etc.). The method of using a powder feeder is preferred because it tends to have excellent controllability of the speed at which diphosphorus pentoxide and/or alumina is added.

Regarding the above-mentioned respective devices, adding means, containers, etc. (for example, a device used when reacting compound (1) with diphosphorus pentoxide, a container containing compound (1), diphosphorus pentoxide, and alumina, a liquid delivery pump used when adding compound (1), a powder feeder used when adding compound (2) and/or alumina, etc.), and piping and the like connecting each of them, materials used in the places in contact with compound (1), compound (2), and alumina are not particularly limited as long as they are commonly used materials, and examples thereof include metals, metal alloys, resins, composite materials of metals and resins, ceramics, etc. More specific examples include titanium, nickel, zirconia, platinum, carbon steel, alloy steel, cast iron, stainless steel (SUS304, SUS304L, SUS430, SUS410, SUS316, SUS316L, SUS329J1, SUS329J4L, etc.), nickel-titanium alloys, nickel-chromium-molybdenum alloys (Inconel (registered trademark) 600, 625, 718, X750, etc., Hastelloy (registered trademark) C-22, C276, etc.), nickel-cobalt alloys (Monel (registered trademark) 400, K, S, H, Nickelvac (registered trademark) 400, Nikoros (registered trademark) 400, etc.), nickel-cobalt chromium-molybdenum alloys, nickel-molybdenum alloys (Hastelloy (registered trademark) ALLOY B2, B, etc.), nickel-cobalt alloys, nickel-iron alloys, nickel-tungsten alloys, cobalt-chromium alloys, cobalt-chromium-molybdenum alloys (ELGILOY, PHYNOX (registered trademark), etc.), platinum-enriched stainless steel, fluorine-based resins (Teflon (registered trademark), copolymers of tetrafluoroethylene and perfluoroalkoxyethylene, perfluoroethylene propene copolymers, ethylene tetrafluoroethylene copolymers, polyvinylidene fluoride, polychlorotrifluoroethylene, ethylene chlorotrifluoroethylene copolymers, etc.), polyether ether ketone, polypropylene, polyphenylene ether, polyamide 6, polyamide 66, aromatic polyamide, polyphenylene sulfide, polysulfone, polyether sulfone, polyether imide, polyamide imide, etc.
The above materials may be used alone or in combination of two or more.

<Fluorine-containing sulfonic acid anhydride (2) (compound (2))>
The following general formula (2):
(R ^f SO ₂ ) ₂ O (2)
(In the formula, ^Rf is a saturated or unsaturated aliphatic or aromatic hydrocarbon group in which at least one hydrogen atom is substituted with a fluorine atom, and the ethylene structure in the hydrocarbon group may be substituted with a structure having an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom, ^Rf has a carbon number of 1 to 20, and two ^Rfs may be the same or different.)
It is expressed as:
The fluorine-containing sulfonic acid anhydride (2) may be used alone or in combination of two or more kinds.

In the formula, the details of ^Rf may be the same as those of ^Rf in the general formula (1) representing the fluorine-containing sulfonic acid (1).

As described above, the present invention can suppress solidification in the reaction of fluorine-containing sulfonic acid (1) with diphosphorus pentoxide, and can produce fluorine-containing sulfonic acid anhydride (2) useful as a catalyst for pharmaceuticals, organic synthesis, etc., or as a synthetic raw material with good yield.

The following are examples that specifically explain this embodiment. The present invention is not limited to the following examples as long as they do not depart from the gist of the invention.

The analytical methods used in the examples and comparative examples are as follows:

Particle size analysis
Particle size was measured using a particle size distribution analyzer (MT-3300II manufactured by Microtrac Bell Co., Ltd.). Water was used as the solvent. The amount of sample was adjusted so as to be within the optimal concentration range displayed by the device (usually 0.05 to 2 g).

<Nuclear Magnetic Resonance Analysis (NMR): Molecular Structure Analysis by ¹⁹ F-NMR>
The products obtained in the examples and comparative examples were subjected to molecular structure analysis using ¹⁹ F-NMR under the following measurement conditions.
[Measurement conditions]
Measurement device: JNM-ECZ400S nuclear magnetic resonance device (manufactured by JEOL Ltd.)
Observed nucleus: ^19F
Solvent: deuterated chloroform Standard substance: tetramethylsilane (0.00 ppm)
Observation frequency: 400MHz ( ^1H )
Pulse width: 6.5 μsec Waiting time: 2 sec Number of integrations: 16

<Nuclear Magnetic Resonance Analysis (NMR): Molecular Structure Analysis by ¹ H-NMR>
The products obtained in the examples and comparative examples were subjected to molecular structure analysis using ¹ H-NMR under the following measurement conditions.
[Measurement conditions]
Measurement device: JNM-ECZ400S nuclear magnetic resonance device (manufactured by JEOL Ltd.)
Observed nucleus: ¹ H
Solvent: deuterated chloroform Standard substance: tetramethylsilane (0.00 ppm)
Observation frequency: 400MHz ( ^1H )
Pulse width: 7.3 μsec Waiting time: 5 sec Number of integrations: 8

The raw materials used in the examples and comparative examples are listed below.

[Production Example 1]
(Fluorine-containing sulfonic acid (1) (compound (1))
According to JP 2019-156782 A, compound (5) represented by the following formula (5) was produced.
CF ₂ =CFOCF ₂ CF ₂ SO ₃ Na (5)
Using the obtained compound of formula (5) above, a fluorine-containing sulfonic acid (6) (compound (6)) was produced by the following method with reference to WO 2020/012913.
Compound (5) (800 g, 2.67 mol), 23% by mass sulfuric acid (prepared from sulfuric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) and distilled water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)) (1.71 kg, the amount of sulfuric acid contained was 4.00 mol) was added to a 6 L separable flask, and after stirring, cyclopentyl methyl ether (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) (1.20 kg) was added, and the mixture was stirred for 1 hour and then allowed to stand for 2 hours. The upper cyclopentyl methyl ether phase was collected in a flask, placed in an evaporator set at 45 ° C., and rotated at 120 rpm. The pressure was gradually reduced, and finally reduced to 3.0 kPaA, and then volatile components were distilled off for 4 hours. Distilled water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (600 g) was added to the flask, placed in an evaporator set at 45 ° C., and rotated at 120 rpm. The pressure was gradually reduced until it finally reached 3.0 kPaA, after which the volatile components were distilled off for 2 hours. Furthermore, distilled water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (600 g) was added to the flask, which was then placed in an evaporator set at 45°C and rotated at 120 rpm. The pressure was gradually reduced until it finally reached 3.0 kPaA, after which the volatile components were distilled off for 1 hour. 0.30 g of the resulting concentrate was taken out and analyzed by ¹ H-NMR, and no peak of cyclopentyl methyl ether was detected. 385.4 g of the resulting concentrate was transferred to a flask equipped with a stirrer and a Liebig condenser with a receiver, and nitrogen replacement was performed three times. Cooling water set at -5°C was passed through the Liebig condenser, the flask was placed in an oil bath set at 90°C, stirred, and the pressure was reduced to 0.7 kPaA. After confirming the distillation of the volatile components, the oil bath was gradually heated to 130°C. After 1 hour, the pressure was returned to normal pressure with nitrogen, and the flask was removed from the oil bath. After the flask reached room temperature, the weight of the contents was measured and found to be 316.1g. For analysis, 1,2-dimethoxyethane (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., Wako special grade, dried molecular sieve 4A 1/16 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added, dehydrated, and the molecular sieve 4A 1/16 was removed to adjust the water content.) (1.0g) and benzotrifluoride (manufactured by Tokyo Chemical Industry Co., Ltd.) (0.10g) were added to the obtained contents (0.30g), and the mixture was stirred and then analyzed by ^19F -NMR. As a result, it was found that 297.0g (1.07mol) of fluorine-containing sulfonic acid (6) represented by the following formula (6) was obtained.
_CF2 = _{CFOCF2CF2SO3H} ( _{6 )}
For analysis, 1,2-dimethoxyethane (Fujifilm Wako Pure Chemical Industries, Ltd., Wako special grade, dried molecular sieve 4A 1/16 (Fujifilm Wako Pure Chemical Industries, Ltd.) was added, dehydrated, and the molecular sieve 4A 1/16 was removed to adjust the moisture content) (2.0 g) was added to the content (0.20 g) and stirred, and then the moisture content was analyzed using a Karl Fischer moisture meter (Kyoto Electronics Manufacturing Co., Ltd., MKC-710D). As a result, it was found that the content contained 17.5 g of water. The moisture content of the 1,2-dimethoxyethane used was also measured, and the moisture content of the content was calculated excluding the moisture content contained in the 1,2-dimethoxyethane used.
The product obtained as described above will be referred to as "fluorine-containing compound (6) obtained in Production Example 1" or "compound (6) obtained in Production Example 1" in the following examples, comparative examples, etc.

(Diphosphorus pentoxide)
Phosphorus (V) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako special grade)

(alumina)
Alumina A (KLS-51, manufactured by Rasa Shoji Co., Ltd., particle size 1.8 μm, calculated specific surface area obtained by particle size analysis is 5.0 m ² /mL)
Alumina B (KAM-02, manufactured by Rasa Shoji Co., Ltd., particle size 3.7 μm, calculated specific surface area obtained by particle size analysis is 3.3 m ² /mL)
Alumina C (manufactured by Sumitomo Chemical Co., Ltd., AA-18, particle size 20 μm, calculated specific surface area obtained by particle size analysis is 0.81 m ² /mL)
Alumina D (manufactured by Rasa Shoji Co., Ltd., CA-83F, particle size 64 μm, calculated specific surface area obtained by particle size analysis is 0.26 m ² /mL)
Alumina E (manufactured by Nippon Light Metal Co., Ltd., SA14, particle size 108 μm, calculated specific surface area obtained by particle size analysis is 0.05 m ² /mL)

(others)
- Benzotrifluoride (Tokyo Chemical Industry Co., Ltd.)
- Hexafluorobenzene (Tokyo Chemical Industry Co., Ltd.)

[Example 1]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (30.4 g, 214 mmol) and alumina A (73.5 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 19.8 g (containing 18.6 g (66.9 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 14.7 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. As a result of the analysis, it was found that 14.2 g (26.5 mmol, yield 79.1%) of fluorine-containing sulfonic anhydride (7) represented by the following general formula (7) was obtained. It was also found that 0.39 g (1.4 mmol) of fluorine-containing sulfonic acid (6) was contained. In the analysis, the masses of the fluorine-containing sulfonic anhydride (7) and the fluorine-containing sulfonic acid (6) were calculated from the mass of benzotrifluoride, the integral values of CF ₃ of benzotrifluoride, the fluorine-containing sulfonic anhydride (7), and the CF ₂ of the fluorine-containing sulfonic acid (6).
(CF ₂ = CFOCF ₂ CF ₂ SO ₂ ) ₂ O (7)
¹⁹ F-NMR: δ (ppm) -85.3 (4F), -112.0 (4F), -116.4 (2F), -123.6 (2F), -139.0 (2F)
The yield of the fluorine-containing sulfonic acid anhydride (7) was calculated according to the following formula (1).
Yield (%) of fluorine-containing sulfonic anhydride (7)=substance amount of fluorine-containing sulfonic anhydride (7)/(substance amount of fluorine-containing sulfonic acid (6)×0.5)×100 (1)
For example, the yield (%) of the fluorine-containing sulfonic acid anhydride (7) in this example = 26.5 (mmol) / (66.9 (mmol) × 0.5) × 100 = 79.1.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 3.2 and ε/(γ+δ) was 1.5.

[Example 2]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (24.2 g, 171 mmol) and alumina A (66.1 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 20.2 g (containing 19.0 g (68.2 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 13.2 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 12.2 g (22.7 mmol, yield 66.5%) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.91 g (3.3 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 2.5 and ε/(γ+δ) was 1.5.

[Example 3]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (41.0 g, 289 mmol) and alumina A (91.8 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 19.0 g (containing 17.9 g (64.2 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 12.8 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 12.5 g (23.2 mmol, 72.2% yield) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.21 g (0.8 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 4.5 and ε/(γ+δ) was 1.6.

[Example 4]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (29.0 g, 204 mmol) and alumina A (49.2 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 19.5 g (containing 18.3 g (65.9 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 14.4 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 14.0 g (26.0 mmol, 78.8% yield) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.29 g (1.1 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and sieved through a sieve with 11.2 mm openings, leaving 6.66 g on the sieve and 76.6 g of material passing through the sieve.
In this example, β/α was 3.1 and ε/(γ+δ) was 1.0.

[Example 5]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (15.7 g, 110 mmol) and alumina A (114 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 10.2 g (containing 9.58 g (34.5 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 7.06 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 6.63 g (12.3 mmol, 71.5% yield) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.37 g (1.3 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 3.2 and ε/(γ+δ) was 4.5.

[Example 6]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (31.7 g, 223 mmol) and alumina A (76.7 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 20.0 g (containing 18.8 g (67.6 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When 140° C. and 10 kPaA were maintained, the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. After confirming that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 14.6 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 14.1 g (26.1 mmol, yield 77.3%) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.43 g (1.6 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 3.3 and ε/(γ+δ) was 1.5.

[Example 7]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (29.6 g, 209 mmol) and alumina B (70.7 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 19.3 g (containing 18.1 g (65.2 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 14.7 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 14.2 g (26.3 mmol, yield 80.8%) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.40 g (1.4 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 3.2 and ε/(γ+δ) was 1.5.

[Example 8]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (31.2 g, 220 mmol) and alumina C (75.5 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 19.7 g (containing 18.5 g (66.6 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 14.7 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 14.1 g (26.2 mmol, 78.6% yield) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.44 g (1.6 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 3.3 and ε/(γ+δ) was 1.5.

[Example 9]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (30.3 g, 214 mmol) and alumina D (75.7 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 20.4 g (containing 19.2 g (68.9 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 14.8 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 14.2 g (26.5 mmol, 76.8% yield) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.40 g (1.4 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and sieved through a sieve with 11.2 mm openings. As a result, 15.6 g remained on the sieve and 96.0 g of material passed through the sieve.
In this example, β/α was 3.1 and ε/(γ+δ) was 1.5.

[Example 10]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (32.4 g, 228 mmol) and alumina E (78.8 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 21.1 g (containing 19.8 g (71.3 mmol) of fluorine-containing sulfonic acid (6)). The oil bath was set to 90° C. and stirred for 1 hour, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 15.4 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 14.8 g (27.5 mmol, 77.2% yield) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.50 g (1.8 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, leaving 37.4 g on the sieve and 79.4 g of material passing through the sieve.
In this example, β/α was 3.2 and ε/(γ+δ) was 1.5.

[Example 11]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (29.2 g, 205 mmol) and alumina A (47.0 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 19.0 g (containing 17.9 g (64.2 mmol) of fluorine-containing sulfonic acid (6)). After stirring for 1 hour with the oil bath set to 90° C., the flask was removed from the oil bath and cooled to room temperature. Stirring in the flask was stopped, and alumina A (23.5 g) measured in the space under a nitrogen atmosphere was added to the flask. Stirring was resumed, the flask was placed in an oil bath, the oil bath was set to 90° C. and stirred for 10 minutes, and then stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. After the distillation slowed down, the pressure was gradually reduced to 2 kPaA. After confirming that distillation had ceased, stirring was stopped. After replacing the flask with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, the receiver was removed from the ethanol cooled with dry ice, and the temperature was returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 14.1 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. As a result of the analysis, it was found that 13.6 g (25.3 mmol, yield 78.8%) of fluorine-containing sulfonic anhydride (7) was obtained. It was also found that 0.39 g (1.4 mmol) of fluorine-containing sulfonic acid (6) was contained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 3.2 and ε/(γ+δ) was 1.5.

[Comparative Example 1]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (31.2 g, 219 mmol) was placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 20.3 g (containing 19.1 g (68.6 mmol) of fluorine-containing sulfonic acid (6)). When the oil bath was set to 90° C. and stirring was performed for 1 hour, it was confirmed that the contents of the flask were attached to the stirring rod and the inner surface of the flask, and stirring was not possible. From this, it was determined that solidification occurred in this comparative example.
In this comparative example, β/α was 3.2.

[Comparative Example 2]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (28.2 g, 199 mmol) was placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing the fluorine-containing compound (6) obtained in Production Example 1 were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and the fluorine-containing compound (6) was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of the fluorine-containing compound (6) obtained in Production Example 1 introduced into the flask was 12.0 g (containing 11.3 g (40.5 mmol) of fluorine-containing sulfonic acid (6)). When the oil bath was set to 90° C. and stirring was carried out for 1 hour, it was confirmed that the contents of the flask were attached to the stirring rod and the inner surface of the flask, and stirring was not possible. From this, it was determined that solidification had occurred in this comparative example.
In this comparative example, β/α was 4.9.

[Reference Example 1]
Diphosphorus pentoxide (337 g, 2.37 mol) was placed in a semi-pressurized kneader (MDI Corporation, ND-025) at room temperature in a space with an air atmosphere dried with a membrane dryer (SMC Corporation, IDG100SAV4-03) and a dry column (Nikka Seiko Co., Ltd., DC-L4), and two shafts were rotated in the same direction (one shaft was set at 90 rpm, the other at 60 rpm). Fluorine-containing sulfonic acid (6) (217 g) (containing 204 g (732 mmol) of fluorine-containing sulfonic acid (6)) produced by the same method as in Production Example 1 was gradually added, and kneading was performed for 2 hours. When the rotation of the apparatus was stopped and the contents were taken out, a kneaded product of fluorine-containing sulfonic acid (6) and diphosphorus pentoxide was obtained as a powder.
In this reference example, β/α was 3.2.

[Reference Example 2]
In a space of an air atmosphere dried with a membrane dryer (IDG100SAV4-03, manufactured by SMC Corporation) and a dry column (DC-L4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (146 g, 1.03 mol) and fluorine-containing sulfonic acid (6) (91.0 g) (containing 85.5 g (307 mmol) of fluorine-containing sulfonic acid (6)) produced in the same manner as in Production Example 1 were placed in a kneader (2P-03, manufactured by Primix Corporation) at room temperature, and kneaded for 10 minutes at a revolution setting of 50 rpm, and then kneaded for 50 minutes at a revolution setting of 100 rpm. When the rotation of the apparatus was stopped and the contents were removed, a kneaded product of fluorine-containing sulfonic acid (6) and diphosphorus pentoxide was obtained as a powder.
In this reference example, β/α was 3.3.

[Reference Example 3]
In a space of an air atmosphere dried with a membrane dryer (IDG100SAV4-03, manufactured by SMC Corporation) and a dry column (DC-L4, manufactured by Nikka Seiko Co., Ltd.), a continuous twin-screw kneader (S1KRC, manufactured by Kurimoto Iron Works, Ltd.) was operated with the rotation speed set at 200 rpm, diphosphorus pentoxide (397 g/h, 2.80 mol/h) was supplied using a powder micro-quantitative supplying device (FeedCommu M-030F, manufactured by Nisshin Engineering Inc.), and fluorine-containing sulfonic acid (6) (230 g/h) (as fluorine-containing sulfonic acid (6) 216 g/h (777 mmol/h)) produced in the same manner as in Production Example 1 was supplied using a macro tube pump (MP-1000, manufactured by Tokyo Rikakikai Co., Ltd.), and kneaded. As a result, a kneaded product of fluorine-containing sulfonic acid (6) and diphosphorus pentoxide was obtained as a powder.
In this reference example, β/α was 3.6.

[Example 12]
In a space of a nitrogen atmosphere dried with a dry column (manufactured by Nikka Seiko Co., Ltd., DC-A4), the kneaded product (40.2 g) produced in Reference Example 1 (containing 14.8 g (53.3 mmol) of fluorine-containing sulfonic acid (6) and 24.5 g (173 mmol) of diphosphorus pentoxide) and alumina A (30.7 g) were placed in a flask, a half-moon-shaped stirring rod having a stirring seal and a Liebig condenser having a receiver were attached, and the flask was taken out of the space of the nitrogen atmosphere. A refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., OHB-3100S) set at 40°C, stirred, the oil bath was set to 90°C and stirred for 1 hour, and then stirred at 140°C and 10 kPaA for 20 minutes. When the oil bath was set to 160°C, the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After the flask was replaced with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 12.1 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. As a result of the analysis, it was found that 11.7 g (21.8 mmol, yield 81.9%) of fluorine-containing sulfonic acid anhydride (7) was obtained. It was also found that the product contained 0.27 g (1.0 mmol) of fluorine-containing sulfonic acid (6).
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, ε/(γ+δ) was 0.78.

[Example 13]
In a space with a nitrogen atmosphere dried with a dry column (manufactured by Nikka Seiko Co., Ltd., DC-A4), the kneaded product (38.7 g) produced in Reference Example 2 (containing 14.0 g (50.4 mmol) of fluorine-containing sulfonic acid (6) and 23.9 g (168 mmol) of diphosphorus pentoxide) and alumina A (31.4 g) were placed in a flask, a half-moon-shaped stirring rod with a stirring seal and a Liebig condenser with a receiver were attached, and the flask was taken out of the space with a nitrogen atmosphere. A refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., OHB-3100S) set at 40°C, stirred, the oil bath was set to 90°C and stirred for 1 hour, and then stirred at 140°C 10 kPaA for 20 minutes. When the oil bath was set to 160°C, the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After the flask was replaced with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 11.2 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. As a result of the analysis, it was found that 10.8 g (20.1 mmol, yield 79.8%) of fluorine-containing sulfonic acid anhydride (7) was obtained. It was also found that the product contained 0.32 g (1.2 mmol) of fluorine-containing sulfonic acid (6).
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, ε/(γ+δ) was 0.83.

[Example 14]
In a space of a nitrogen atmosphere dried with a dry column (manufactured by Nikka Seiko Co., Ltd., DC-A4), the kneaded product (39.5 g) produced in Reference Example 3 (containing 13.6 g (49.0 mmol) of fluorine-containing sulfonic acid (6) and 25.1 g (177 mmol) of diphosphorus pentoxide) and alumina A (31.0 g) were placed in a flask, a half-moon-shaped stirring rod having a stirring seal and a Liebig condenser having a receiver were attached, and the flask was taken out of the space of the nitrogen atmosphere. A refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., OHB-3100S) set at 40°C, stirred, the oil bath was set to 90°C and stirred for 1 hour, and then stirred at 140°C 10 kPaA for 20 minutes. When the oil bath was set to 160°C, the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. When it was confirmed that distillation had ceased, stirring was stopped. After the flask was replaced with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 10.8 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. As a result of the analysis, it was found that 10.4 g (19.3 mmol, yield 78.8%) of fluorine-containing sulfonic acid anhydride (7) was obtained. It was also found that the product contained 0.29 g (1.0 mmol) of fluorine-containing sulfonic acid (6).
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, ε/(γ+δ) was 0.80.

[Comparative Example 3]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), the kneaded product (38.6 g) produced in Reference Example 1 was placed in a flask, a half-moon-shaped stirring rod with a stirring seal and a Liebig condenser with a receiver were attached, and the flask was taken out of the space with a nitrogen atmosphere. A refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, stirred, and the oil bath was set to 90°C and stirred for 1 hour, and it was confirmed that the contents of the flask were attached to the stirring rod and the inner surface of the flask and could not be stirred. From this, it was determined that solidification occurred in this comparative example.

[Comparative Example 4]
In a space with a nitrogen atmosphere dried with a dry column (manufactured by Nikka Seiko Co., Ltd., DC-A4), the kneaded product (39.2 g) produced in Reference Example 2 was placed in a flask, a half-moon-shaped stirring rod with a stirring seal and a Liebig condenser with a receiver were attached, and the flask was taken out of the space with a nitrogen atmosphere. A refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., OHB-3100S) set at 40°C, stirred, and the oil bath was set to 90°C and stirred for 1 hour, and it was confirmed that the contents of the flask were attached to the stirring rod and the inner surface of the flask and could not be stirred. From this, it was determined that solidification occurred in this comparative example.

[Comparative Example 5]
In a space with a nitrogen atmosphere dried with a dry column (manufactured by Nikka Seiko Co., Ltd., DC-A4), the kneaded product (41.0 g) produced in Reference Example 2 was placed in a flask, a half-moon-shaped stirring rod with a stirring seal and a Liebig condenser with a receiver were attached, and the flask was taken out of the space with a nitrogen atmosphere. A refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., OHB-3100S) set at 40°C, stirred, and the oil bath was set to 90°C and stirred for 1 hour, and it was confirmed that the contents of the flask were attached to the stirring rod and the inner surface of the flask and could not be stirred. From this, it was determined that solidification occurred in this comparative example.

[Example 15]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (12.8 g, 90.1 mmol) and alumina A (57.4 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing trifluoromethanesulfonic acid (Wako Special Grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and trifluoromethanesulfonic acid was gradually dropped while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of trifluoromethanesulfonic acid introduced into the flask was 25.5 g (170 mmol). The oil bath was set to 90° C., and the mixture was stirred at 90 kPaA, and the distillate was gradually collected in the receiver. When it was confirmed that the distillate had ceased to be distilled, the stirring was stopped. After the flask was substituted with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, and the flask was sealed with a glass stopper, and then the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 20.0 g. The contents of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. As a result of analysis, it was found that 19.2 g (68.1 mmol, yield 80.2%) of fluorine-containing sulfonic acid anhydride (2) was obtained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 0.53 and ε/(γ+δ) was 1.5.

[Example 16]
In a space with a nitrogen atmosphere dried with a dry column (DC-A4, manufactured by Nikka Seiko Co., Ltd.), diphosphorus pentoxide (14.6 g, 103 mmol) and alumina A (68.5 g) were placed in a flask, and a crescent-shaped stirring rod with a stirring seal, a Liebig condenser with a receiver, a three-way cock, and a dropping funnel containing nonafluoro-1-butanesulfonic acid (manufactured by Tokyo Kasei Kogyo Co., Ltd.) were attached, and the flask was taken out of the space with a nitrogen atmosphere. Dry nitrogen was introduced from the three-way cock, a refrigerant at -5°C was circulated through the Liebig condenser, and the receiver attached to the Liebig condenser was cooled with ethanol cooled with dry ice. The flask was placed in an oil bath (OHB-3100S, manufactured by Tokyo Rikakikai Co., Ltd.) set at 40°C, and nonafluoro-1-butanesulfonic acid was gradually dropped into the flask while stirring. After the dropping was completed, the dropping funnel and the three-way cock were removed, and a glass stopper was attached. At this time, the amount of nonafluoro-1-butanesulfonic acid introduced into the flask was 30.2 g (101 mmol). After stirring for 1 hour with the oil bath set to 90° C., the mixture was stirred for 20 minutes at 140° C. and 10 kPaA. When the oil bath was set to 160° C., the distillate was gradually collected in the receiver. When the distillation slowed down, the pressure was gradually reduced to 2 kPaA. After confirming that distillation had ceased, the stirring was stopped. After the flask was substituted with nitrogen, it was removed from the oil bath, the flow of the refrigerant in the Liebig condenser was stopped, and the receiver was removed from the ethanol cooled with dry ice and returned to room temperature. The Liebig condenser was removed from the flask, the flask was sealed with a glass stopper, and the flask was moved to a space with a dry nitrogen atmosphere. The weight of the contents of the receiver was measured and found to be 24.1 g. The content of the receiver (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. The analysis showed that 23.0 g (39.5 mmol, yield 78.5%) of fluorine-containing sulfonic anhydride (2) was obtained.
The contents of the flask were transferred to a dry nitrogen atmosphere and passed through a sieve with 11.2 mm openings, resulting in no material remaining on the sieve.
In this example, β/α was 1.0 and ε/(γ+δ) was 1.5.

[Example 17]
The contents of the receiver containing the fluorine-containing sulfonic anhydride (7) obtained in Examples 1 to 4, 11, and 12 to 14 were placed in a flask of a distillation apparatus (Sulzer EX Laboratory Packing manufactured by Sulzer was used as a packing material) and distilled. 3.88 g of the initial fraction was separated, and 91.5 g of the main fraction was obtained. The main fraction (0.30 g), hexafluorobenzene (1.30 g), and benzotrifluoride (0.10 g) were mixed and analyzed by ¹⁹ F-NMR. As a result of the analysis, the purity of the fluorine-containing sulfonic anhydride (7) was 99%.

The production method of the present invention can suppress solidification in the reaction between fluorine-containing sulfonic acid (1) and diphosphorus pentoxide, and can produce fluorine-containing sulfonic anhydride (2) in good yield, and can therefore be suitably used in the production of raw materials that are useful as catalysts for pharmaceuticals, organic synthesis, etc., or as synthetic raw materials.

Claims (4)

The following general formula (2):
(R ^f SO ₂ ) ₂ O (2)
₍ In the formula, ^Rf is a saturated or unsaturated aliphatic hydrocarbon group, and when the hydrocarbon group has -CH2- , _the -CH2- may be substituted with a structure having an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom, and all of the hydrogen atoms in the hydrocarbon group other than the hydrogen atoms of the substituted -CH2- _are substituted with fluorine atoms, the number of carbon atoms in ^Rf is 1 to 20, and the two ^Rfs may be the same or different.)
The present invention relates to a method for producing a fluorine-containing sulfonic acid anhydride (2) represented by the following formula:
The following general formula (1):
R ^f SO ₃ H (1)
(In the formula, R ^f is a saturated or unsaturated aliphatic hydrocarbon group, and when the hydrocarbon group has -CH ₂ - , the -CH ₂ - may be substituted with a structure having an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom, and all of the hydrogen atoms in the hydrocarbon group other than the hydrogen atoms of the substituted -CH ₂ - are substituted with fluorine atoms, and R ^f has 1 to 20 carbon atoms.)
A fluorine-containing sulfonic acid (1) represented by the formula:
Diphosphorus pentaoxide and
A production method, characterized in that the reaction is carried out in the coexistence of alumina. The method according to claim 1, wherein the ratio (β/α) of the amount of substance (β) (unit: mmol) of diphosphorus pentoxide to the amount of substance (α) (unit: mmol) of fluorine-containing sulfonic acid (1) is 0.1 to 100. The method according to claim 1 or 2, wherein the ratio (ε/(γ+δ)) of the mass (ε) (unit: g) of alumina to the total mass (γ+δ) (unit: g) of the mass (γ) (unit: g) of the fluorine-containing sulfonic acid (1) and the mass (δ) (unit: g) of diphosphorus pentoxide is 0.1 to 100. The method according to any one of claims 1 to 3, wherein the reaction temperature is from -40 to 300°C.