JP7711522B2 - Method for producing unsaturated carboxylic acid hexafluoroisopropyl ester - Google Patents

Description

The present invention relates to a method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester.

An unsaturated carboxylic acid hexafluoroisopropyl ester is a compound useful as a raw material monomer for a polymer.
For example, hexafluoroisopropyl α-chloroacrylate, which is one of the unsaturated carboxylic acid hexafluoroisopropyl esters, is used as a raw material monomer for copolymers used as main chain scission type positive resists in fields such as semiconductor manufacturing (see, for example, Patent Document 1).

As methods for producing such unsaturated carboxylic acid hexafluoroisopropyl esters, for example, Patent Document 2 discloses a method in which methacrylic acid chloride is reacted with 1,1,1,3,3,3-hexafluoroisopropanol (hereinafter sometimes simply referred to as "hexafluoroisopropanol") in pyridine under heated conditions, and a method in which acrylic acid is reacted with trifluoroacetic anhydride as a dehydrating condensation agent to produce acrylic anhydride, and this acrylic anhydride is then further reacted with hexafluoroisopropanol.

Patent Document 3 also discloses a method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester by reacting hexafluoroisopropanol with methacrylic acid in the presence of phosphoric anhydride as a dehydrating condensation agent.

Furthermore, Patent Document 4 discloses a method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester, which is characterized in that water is made to coexist as a solvent when hexafluoroisopropanol is reacted with acrylic anhydride or methacrylic anhydride in the presence of a base.

JP 2021-067811 A U.S. Pat. No. 3,177,185 Japanese Unexamined Patent Publication No. 2-295948 JP 2008-150339 A

Here, hexafluoroisopropanol, which is the raw material for unsaturated carboxylic acid hexafluoroisopropyl ester, contains two trifluoromethyl groups, which are strong electron-withdrawing groups, and is a secondary alcohol with high acidity, so it has low reactivity and is unlikely to cause an esterification reaction of unsaturated carboxylic acid. Therefore, in the method disclosed in Patent Document 2 in which methacrylic acid chloride and hexafluoroisopropanol are reacted in pyridine, the yield of unsaturated carboxylic acid hexafluoroisopropyl ester is extremely low even under heated conditions. In addition, in the method in which acrylic acid is reacted with trifluoroacetic anhydride as a dehydrating condensation agent to produce acrylic anhydride, and this acrylic anhydride is further reacted with hexafluoroisopropanol, the yield of unsaturated carboxylic acid hexafluoroisopropyl ester is also low.

In the method of Patent Document 3, unsaturated carboxylic acid hexafluoroisopropyl ester can be obtained in a relatively high yield, but the dehydration condensation agent phosphoric anhydride is very difficult to handle because it easily absorbs moisture. In addition, phosphoric anhydride reacts with water after the reaction to form phosphoric acid, which makes the reaction mixture viscous, making it difficult to remove the reaction mixture from the reactor. Furthermore, when acrylic acid is used as a raw material, the yield of the ester obtained is low and oligomers are formed, so in the method of Patent Document 2, methacrylic acid must be used as a raw material, which is a problem in that only methacrylic acid hexafluoroisopropyl ester is obtained as a product.

In the method of Patent Document 4, since water is used as a solvent, separation and purification of the product after the reaction is easy, and unsaturated carboxylic acid hexafluoroisopropyl ester is obtained in high yield. However, it is difficult to obtain the raw materials acrylic anhydride and methacrylic anhydride in large quantities with high purity, and as a result, acrylic anhydride and methacrylic anhydride tend to be very expensive. Therefore, from an industrial perspective, there is a problem in that it is disadvantageous from the standpoint of economics to use these raw materials.

The present invention was made under such circumstances, and the object of the present invention is to provide a method for producing unsaturated carboxylic acid hexafluoroisopropyl esters in good yield with simple operations and in an economically advantageous manner on an industrial scale.

The present inventors have conducted extensive research to achieve the above object. They have discovered that by contacting hexafluoroisopropanol with an unsaturated carboxylic acid halide in a specific mixed solvent, it is possible to produce an unsaturated carboxylic acid hexafluoroisopropyl ester in good yield and with economical industrial advantages through a simple procedure, and have completed the present invention.

That is, an object of the present invention is to advantageously solve the above-mentioned problems, and the present invention provides a compound represented by the following formula (1):
[In the formula (1), X represents a hydrogen atom, a halogen atom, or a methyl group.], the method comprises reacting 1,1,1,3,3,3-hexafluoroisopropanol with a compound represented by the following formula (2):
[In formula (2), X is the same as X in formula (1), and Y represents a halogen atom selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.], in a mixed solvent containing a water-immiscible organic solvent and water, the mixed solvent containing at least one alkali metal salt selected from the group consisting of an alkali metal carbonate, an alkali metal hydrogen carbonate, an alkali metal phosphate, and an alkali metal hydrogen phosphate, and a phase transfer catalyst. With such a method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester, the unsaturated carboxylic acid hexafluoroisopropyl ester can be produced in good yield with a simple operation and in an economically advantageous manner on an industrial scale.

In the process for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention, the phase transfer catalyst is preferably at least one salt selected from the group consisting of alkylammonium halide salts and alkylammonium sulfate salts.
When the phase transfer catalyst is at least one salt selected from the group listed above, the unsaturated carboxylic acid hexafluoroisopropyl ester can be produced industrially in a higher yield with a simpler operation and in a more economical manner.

In the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention, the unsaturated carboxylic acid halide represented by the formula (2) is preferably at least one compound selected from the group consisting of acrylic acid chloride, α-chloroacrylic acid chloride, and α-bromoacrylic acid chloride.
When the unsaturated carboxylic acid halide represented by formula (2) is at least one compound selected from the group listed above, the unsaturated carboxylic acid hexafluoroisopropyl ester can be produced industrially in an economically advantageous manner.

In the process for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention, X in the formula (1) is preferably a hydrogen atom, a chlorine atom, or a methyl group.
The unsaturated carboxylic acid hexafluoroisopropyl ester in which X in formula (1) is a hydrogen atom, a chlorine atom, or a methyl group has good stability and can be advantageously used as a monomer for producing a polymer.

The present invention provides a method for producing unsaturated carboxylic acid hexafluoroisopropyl esters in good yield with simple operations and in an economically advantageous industrial manner.

Hereinafter, an embodiment of the present invention will be described in detail.
Here, the unsaturated carboxylic acid hexafluoroisopropyl ester produced by the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention is not particularly limited, and can be advantageously used, for example, as a monomer utilized in the production of a polymer. Specifically, it can be advantageously used in the production of a polymer that can be suitably used as a main chain scission type positive resist, in which the main chain is scissed by irradiation with ionizing radiation such as an electron beam or short wavelength light such as ultraviolet light, and the molecular weight is reduced.

(Method for producing unsaturated carboxylic acid hexafluoroisopropyl ester)
The method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention comprises a step of contacting 1,1,1,3,3,3-hexafluoroisopropanol ((CF ₃ ) ₂ CHOH) with an unsaturated carboxylic acid halide represented by formula (2) described below in a mixed solvent containing a water-immiscible organic solvent and water. The mixed solvent also contains at least one alkali metal salt selected from the group consisting of alkali metal carbonates, alkali metal hydrogen carbonates, alkali metal phosphates, and alkali metal hydrogen phosphates, and a phase transfer catalyst.
According to the method for producing the unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention, the unsaturated carboxylic acid hexafluoroisopropyl ester can be produced in good yield by simple operations and in an industrially advantageous manner in terms of economic efficiency. The reason why the unsaturated carboxylic acid hexafluoroisopropyl ester can be produced in good yield by simple operations is not necessarily clear, but is presumed to be as follows.

First, hexafluoroisopropanol, which is a raw material for unsaturated carboxylic acid hexafluoroisopropyl ester, has six fluorine atoms, but has the property of being mixed with water in any ratio, so water can be suitably used as a solvent. In addition, hexafluoroisopropanol has two trifluoromethyl groups, which have very large electron-withdrawing properties, so it has the property of being highly acidic among alcohols.
In the present invention, by using a mixed solvent containing a water-immiscible organic solvent and water, a hexafluoroisopropoxide salt (which may exist in an ionic dissociated state because it is dissolved in water) is formed in water by a weak acid-alkali reaction from hexafluoroisopropanol and an alkali metal salt acting as a base. It is considered that an unsaturated carboxylic acid hexafluoroisopropyl ester is generated by contacting the formed hexafluoroisopropoxide salt with an unsaturated carboxylic acid halide. The generated unsaturated carboxylic acid hexafluoroisopropyl ester is present in the water-immiscible organic solvent, and the by-product alkali metal halide is present in water, so that the unsaturated carboxylic acid hexafluoroisopropyl ester can be easily separated. In addition, the phase transfer catalyst contained in the mixed solvent facilitates contact between the hexafluoroisopropoxide salt and the unsaturated carboxylic acid halide, and as a result, the generation of the unsaturated carboxylic acid hexafluoroisopropyl ester can be promoted.
For the above reasons, it is believed that the unsaturated carboxylic acid hexafluoroisopropyl ester can be produced in good yield by a simple procedure.

<Unsaturated Carboxylic Acid Halide>
The unsaturated carboxylic acid halide used in the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention is a compound represented by the following formula (2).

In addition, in formula (2), X is the same as X in formula (1) described below. That is, in formula (2), X represents a hydrogen atom, a halogen atom, or a methyl group. Since the unsaturated carboxylic acid halide represented by formula (2) is relatively inexpensive and available, the unsaturated carboxylic acid hexafluoroisopropyl ester can be industrially produced in an economically advantageous manner by using it as a raw material.
Examples of the unsaturated carboxylic acid halide represented by formula (2) include acrylic acid chloride, α-substituted acrylic acid chlorides such as methacrylic acid chloride, α-fluoroacrylic acid chloride, α-chloroacrylic acid chloride, α-bromoacrylic acid chloride, and α-iodoacrylic acid chloride, acrylic acid bromide, and α-substituted acrylic acid bromides such as methacrylic acid bromide, α-chloroacrylic acid bromide, and α-bromoacrylic acid bromide. Among these, it is preferable to use at least one compound selected from the group consisting of acrylic acid chloride, methacrylic acid chloride, α-fluoroacrylic acid chloride, α-chloroacrylic acid chloride, and α-bromoacrylic acid chloride, because they are less expensive, more easily available, and more advantageous industrially in terms of economic efficiency, and it is more preferable to use at least one compound selected from the group consisting of acrylic acid chloride, α-chloroacrylic acid chloride, and α-bromoacrylic acid chloride.

Acryloyl chloride, methacrylic acid chloride, and the like are industrially produced, so commercially available products can be used as they are. α-Substituted unsaturated carboxylic acid halides in which the α-position is substituted with a halogen atom can be synthesized according to the methods described in the following documents.
α-Fluoroacrylic acid chloride can be synthesized, for example, according to the method described in JP-A-2004-505939. Specifically, 2-chloro-2-fluoropropionic acid obtained by reacting 2,2-dichloropropionic acid with hydrogen fluoride is treated with sodium hydroxide to form 2-fluoroacrylic acid, and the resulting 2-fluoroacrylic acid is mixed with thionyl chloride and heated under reflux to obtain the target product, 2-fluoroacrylic acid chloride (α-fluorine atom-fluoroacrylic acid chloride).
α-Chloroacrylic acid chloride can be synthesized, for example, according to the method described in JP-A No. 2002-173467. Specifically, α-chloroacrylic acid chloride can be obtained by reacting α-chloroacrylic acid with thionyl chloride or oxalyl chloride.
α-Bromoacrylic acid chloride can be synthesized, for example, according to the method described in JP 2005-126340 A. Specifically, 2-bromoacrylic acid chloride (α-bromoacrylic acid chloride) can be obtained by reacting 2,3-dibromopropionyl chloride with triethylamine and dehydrobrominating it.

The amount of the unsaturated carboxylic acid halide represented by formula (1) used is preferably 1.1 mol or more, more preferably 1.5 mol or more, and preferably 3 mol or less, more preferably 2.5 mol or less, per mol of the raw material hexafluoroisopropanol.
When the amount of the unsaturated carboxylic acid halide represented by formula (1) used is equal to or more than the lower limit, the yield of the target unsaturated carboxylic acid hexafluoroisopropyl ester can be improved. On the other hand, when the amount of the unsaturated carboxylic acid halide represented by formula (1) used is equal to or less than the upper limit, the occurrence of undesirable side reactions, such as the production of acrylic acid oligomers, can be suppressed.

<Alkali Metal Salt>
The alkali metal salt used in the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention is at least one metal salt selected from the group consisting of alkali metal carbonates, alkali metal hydrogen carbonates, alkali metal phosphates, and alkali metal hydrogen phosphates.
Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, potassium carbonate, and cesium carbonate.
Examples of the alkali metal hydrogen carbonate include sodium hydrogen carbonate, potassium hydrogen carbonate, and cesium hydrogen carbonate.
Examples of the alkali metal phosphate include trisodium phosphate and tripotassium phosphate.
Examples of the alkali metal hydrogen phosphate include disodium hydrogen phosphate and dipotassium hydrogen phosphate.
The alkali metal salt is preferably an alkali metal carbonate such as sodium carbonate, potassium carbonate, or cesium carbonate, because a hexafluoroisoproxide salt can be efficiently formed in water, and from the viewpoint of economy, it is more preferably at least one alkali metal salt selected from the group consisting of sodium carbonate and potassium carbonate, and further preferably potassium carbonate, because it can produce an unsaturated carboxylic acid hexafluoroisopropyl ester in a higher yield.

The amount of the alkali metal salt used is preferably 1 mol or more, more preferably 1.2 mol or more, and preferably 3 mol or less, more preferably 2 mol or less, per mol of the raw material hexafluoroisopropanol.
If the amount of the alkali metal salt used is equal to or more than the lower limit, the hexafluoroisopropoxide salt can be efficiently formed in water, and the yield of the unsaturated carboxylic acid hexafluoroisopropyl ester can be improved. On the other hand, if the amount of the alkali metal salt used is equal to or less than the upper limit, the alkali metal salt can be prevented from being insufficiently dissolved in water or from precipitating during the reaction, and post-treatment can be facilitated.

<Mixed Solvent>
The mixed solvent used in the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention contains a water-immiscible organic solvent and water, and further contains at least one alkali metal salt selected from the group consisting of alkali metal carbonates, alkali metal hydrogen carbonates, alkali metal phosphates, and alkali metal hydrogen phosphates, and a phase transfer catalyst.

The amount of water contained in the mixed solvent is not particularly limited as long as it is an amount capable of dissolving the alkali metal salt, but is preferably at least 2 times, more preferably at least 3 times, and preferably not more than 50 times, and more preferably not more than 10 times, the amount of hexafluoroisopropanol used as the raw material, on a mass basis.
If the amount of water is equal to or more than the lower limit, the concentration of the alkali metal salt can be prevented from becoming too high, and the reaction can be prevented from proceeding too rapidly and causing undesirable side reactions, whereas if the amount of water is equal to or less than the upper limit, the amount of wastewater can be reduced, making post-treatment after the reaction easier.

The water-immiscible organic solvent contained in the mixed solvent is a solvent that is essentially immiscible with water. As the water-immiscible organic solvent, it is preferable to use a solvent having a boiling point higher than that of the target unsaturated carboxylic acid hexafluoroisopropyl ester. If such a water-immiscible organic solvent is used, the generated unsaturated carboxylic acid hexafluoroisopropyl ester and the water-immiscible organic solvent can be easily separated by distillation or the like.
The water-immiscible organic solvent can be appropriately selected depending on the type of unsaturated carboxylic acid hexafluoroisopropyl ester, and examples thereof include ether-based solvents such as cyclopentyl methyl ether, 4-methyltetrahydropyran, and dibutyl ether, and aromatic hydrocarbon-based solvents such as toluene, xylene, benzotrifluoride, bis(trifluoromethyl)benzene, and chlorobenzene. Among these, inexpensive solvents such as toluene, xylene, benzotrifluoride, and bis(trifluoromethyl)benzene can be preferably used. In addition, although the reason is unclear, toluene or xylene can be preferably used as the water-immiscible organic solvent because it allows the unsaturated carboxylic acid hexafluoroisopropyl ester to be produced in a higher yield.

The amount of the water-immiscible organic solvent contained in the mixed solvent is preferably 0.5 times or more, more preferably 1 time or more, and preferably 5 times or less, more preferably 2 times or less, based on the amount of water on a volume basis.
When the amount of the water-immiscible organic solvent used is equal to or more than the lower limit, the amount of the unsaturated carboxylic acid hexafluoroisopropyl ester to be extracted increases, and the yield can be improved. On the other hand, when the amount of the water-immiscible organic solvent used is equal to or less than the upper limit, the amount of the organic solvent used is prevented from becoming excessive, and the unsaturated carboxylic acid hexafluoroisopropyl ester can be produced economically advantageously.
In this specification, the "amount of the water-immiscible organic solvent contained in the mixed solvent" means the amount of the water-immiscible organic solvent contained in the mixed solvent when hexafluoroisopropanol and the unsaturated carboxylic acid halide are contacted (reacted).

<Phase transfer catalyst>
The phase transfer catalyst used in the method for producing unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention is not particularly limited as long as it is generally used in the reaction of a two-phase mixed solvent, and examples thereof include quaternary salts such as quaternary ammonium halides and quaternary phosphonium halides; polyethers such as crown ethers and polyoxyalkylene glycols; and amino alcohols. Among these, quaternary salts are particularly preferred because they exist in the aqueous phase after the reaction is completed and are easy to separate. Quaternary salts consist of a cation (positive ion) generated by bonding four carbon-containing substituents to heteroatoms such as nitrogen and phosphorus atoms, and a counter anion (negative ion).

The heteroatom is not particularly limited as long as it is an atom of Group 5B of the periodic table, but a nitrogen atom and a phosphorus atom are preferred, and a nitrogen atom is particularly preferred because it has good compatibility with hexafluoroisopropoxide ions formed in water and can improve the yield of the product. In addition, when an unsaturated carboxylic acid chloride is used as the raw material unsaturated carboxylic acid halide, a nitrogen atom is particularly preferred as the heteroatom because it also has good compatibility with chlorine atoms.
The number of carbon atoms in the four carbon-containing substituents of the heteroatom is not particularly limited, but is usually 1 to 30, preferably 1 to 20. The carbon-containing substituent is not particularly limited as long as it contains a carbon directly bonded to the heteroatom, and examples thereof include an alkyl group, an aryl group, an aralkyl group, an alkenyl group, and an alkynyl group. These carbon-containing substituents may include substituents that do not affect the reaction, such as an alkoxy group, a halogen atom, and an alkylthio group; and divalent substituents that do not affect the reaction, such as a carbonyl group, a sulfonyl group, and a sulfinyl group, may be included in the carbon-containing substituent structure. In addition, the carbon-containing substituents may be bonded to each other to form a ring. The carbon-containing substituent is preferably an alkyl group, an aryl group, or an aralkyl group.

Specific examples of carbon-containing substituents include alkyl groups such as methyl, ethyl, propyl, butyl, octyl, lauryl, and hexadecyl; aryl groups such as phenyl, 2-methylphenyl, 4-methylphenyl, 4-ethylphenyl, and naphthyl; and aralkyl groups such as benzyl, 2-methylbenzyl, 4-methylbenzyl, 2-methoxybenzyl, and 4-methoxybenzyl. Examples of quaternary salts in which carbon-containing substituents are bonded to each other to form a ring include pyridinium and picolinium, in which the carbon-containing substituents are cyclic and bonded to a nitrogen atom. These carbon-containing substituents may have a substituent that does not affect the reaction.

The quaternary salts preferably have three or more carbon-containing substituents bonded to a heteroatom, each of which preferably has two or more carbon atoms, more preferably has three or more carbon atoms, and preferably has seven or fewer carbon atoms, more preferably has five or fewer carbon atoms.
Quaternary salts having three or more carbon-containing substituents bonded thereto and having a carbon number within the above range can improve the yield of unsaturated carboxylic acid hexafluoroisopropyl ester. The reason for this is unclear, but it is presumed to be due to an interaction with the hexafluoroisopropoxide ion formed in water, the solubility of the resulting cation in a water-immiscible organic solvent, or the like.

Examples of counter anions (negative ions) include halides, hydroxides, and hydrogen sulfate ions, with halide or hydrogen sulfate ions being preferred, and halide being more preferred. Specific examples of halides include, but are not limited to, fluoride, bromide, chloride, and iodide, with bromide and chloride being preferred.

Specific examples of quaternary salts include quaternary ammonium halides, quaternary phosphonium halides, quaternary ammonium hydroxides, quaternary phosphonium hydroxides, quaternary ammonium hydrogen sulfates, and quaternary phosphonium hydrogen sulfates. Among these, quaternary ammonium halides, quaternary ammonium hydrogen sulfates, and quaternary phosphonium halides are preferred, and quaternary ammonium halides or quaternary ammonium hydrogen sulfates are more preferred, and quaternary ammonium halides are even more preferred, because they are compatible with the hexafluoroisopropoxide ion formed in water and can improve the yield of unsaturated carboxylic acid hexafluoroisopropyl ester.

Specific examples of quaternary ammonium halides include tetramethylammonium bromide, tetramethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride, cetyltrimethylammonium bromide, benzyltriethylammonium chloride, and trioctylmethylammonium chloride.
Examples of quaternary ammonium hydrogen sulfates include tetramethylammonium hydrogen sulfate and tetrabutylammonium hydrogen sulfate.
Examples of the quaternary phosphonium halides include tetrabutylphosphonium bromide, benzyltriphenylphosphonium chloride, and butyltriphenylphosphonium bromide.
Among those listed above, tetrabutylammonium bromide, tetrabutylammonium chloride, cetyltrimethylammonium bromide, benzyltriethylammonium chloride, trimethylbenzylammonium bromide, and tetrabutylammonium hydrogen sulfate are preferred, and tetrabutylammonium bromide and tetrabutylammonium hydrogen sulfate are more preferred.

Examples of crown ethers include 15-crown-5, 18-crown-6, dibenzo-18-crown-6, dibenzo-24-crown-8, and dicyclohexyl-18-crown-6.
Examples of polyoxyalkylene glycols include polyethylene glycol, polypropylene glycol, and polyethylene glycol monomethyl ether.
Examples of the amino alcohols include tris[2-(2-methoxyethoxy)ethyl]amine, cryptate, and the like.

The above-mentioned phase transfer catalysts can be used alone or in combination of two or more.

The amount of phase transfer catalyst used can be appropriately selected depending on the reaction conditions, but is usually 0.001 mol or more, preferably 0.01 mol or more, more preferably 0.03 mol, and usually 1 mol or less, preferably 0.1 mol or less, more preferably 0.07 mol or less per 1 mol of the raw material hexafluoroisopropanol.

<Additives>
In the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention, additives may be used within the scope of the purpose of the method. Examples of additives include polymerization inhibitors.

In the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention, a polymerization inhibitor may be added to the reaction system as necessary to prevent unexpected side reactions (polymerization) during the reaction. Examples of polymerization inhibitors include phenolic compounds such as hydroquinone, p-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, tert-butyl-catechol, 2,6-di-tert-butyl-4-methylphenol, pentaerythritol, tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), and 2-sec-butyl-4,6-dinitrophenol; N,N'-diisopropylparaphenylenediamine, N,N'-di-2-naphthylparaphenylenediamine, and N-phenylene. Amine compounds such as -N'-(1,3-dimethylbutyl)paraphenylenediamine, N,N'-bis(1,4-dimethylphenyl)-paraphenylenediamine, and N-(1,4-dimethylphenyl)-N'-phenyl-paraphenylenediamine; N-oxyl compounds such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl, and bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)sebacate; and metal compounds such as copper, copper(II) chloride, and iron(III) chloride.

The amount of polymerization inhibitor used can be determined appropriately, but it is preferable that the amount is 10 ppm or more relative to the raw material hexafluoroisopropanol, and more preferably 50 ppm or more since this produces good effects.

<Reaction conditions>
In the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention, the contact between hexafluoroisopropanol and an unsaturated carboxylic acid halide is not particularly limited as long as it is carried out in the above-mentioned mixed solvent. For example, the contact can be carried out by adding hexafluoroisopropanol to an aqueous solution containing an alkali metal salt, then adding a water-immiscible organic solvent and a phase transfer catalyst, and further dropping the unsaturated carboxylic acid halide thereto.

The temperature (reaction temperature) at which hexafluoroisopropanol is contacted with the unsaturated carboxylic acid halide is a temperature at which the aqueous solution of the alkali metal salt does not solidify and the reaction does not proceed excessively, and is preferably 0°C or higher, more preferably 10°C or higher, and is preferably 40°C or lower, and more preferably 30°C or lower.
If the reaction temperature is equal to or higher than the lower limit, the reaction rate can be efficiently increased and the time required for the reaction to be completed can be shortened, whereas if the reaction temperature is equal to or lower than the upper limit, polymerization of the raw materials, products, and the like can be suppressed.

The reaction time can be appropriately determined depending on the reaction temperature and the like, but is preferably 0.5 hours or more, more preferably 1 hour or more, and is preferably 20 hours or less, more preferably 10 hours or less.
If the reaction time is equal to or longer than the lower limit, the reaction can be completed and the yield can be improved, whereas if the reaction time is equal to or shorter than the upper limit, polymerization of the raw materials, products, etc. can be suppressed.

After completion of the reaction, any of the following steps may be carried out: for example, a step of allowing the mixed solvent containing the product to stand in order to separate into a water-immiscible organic solvent phase and an aqueous phase; a step of separating the water-immiscible organic solvent phase and the aqueous phase; a step of removing the aqueous phase from the phase-separated mixed solvent; a step of washing the remaining water-immiscible organic solvent phase with a dilute acid such as dilute hydrochloric acid, a saturated aqueous sodium bicarbonate solution, and a saturated saline solution; a step of drying (dehydrating) the washed water-immiscible organic solvent phase with a desiccant such as magnesium sulfate; and a step of distilling the dried water-immiscible organic solvent phase.
The progress of the reaction can be monitored by gas chromatography, etc. The completion of the reaction can be confirmed by the disappearance of the raw material hexafluoroisopropanol.

<Unsaturated carboxylic acid hexafluoroisopropyl ester>
The unsaturated carboxylic acid hexafluoroisopropyl ester obtained by the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention is a compound represented by the following formula (1).

In the formula (1), X represents a hydrogen atom, a halogen atom, or a methyl group.
That is, examples of the unsaturated carboxylic acid hexafluoroisopropyl ester represented by formula (1) include hexafluoroisopropyl acrylate, hexafluoroisopropyl methacrylate, hexafluoroisopropyl α-fluoroacrylic acid, hexafluoroisopropyl α-chloroacrylic acid, hexafluoroisopropyl α-bromoacrylic acid, and hexafluoroisopropyl α-iodoacrylic acid.
X in formula (1) is preferably a hydrogen atom, a chlorine atom, or a methyl group, since these have good stability and can be more advantageously used as a monomer for producing a polymer. That is, the unsaturated carboxylic acid hexafluoroisopropyl ester represented by formula (1) is preferably acrylic acid hexafluoroisopropyl ester, α-chloroacrylic acid hexafluoroisopropyl ester, or methacrylic acid hexafluoroisopropyl ester.

The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the following examples. Note that "%" refers to "% by mass" unless otherwise specified.

The analysis conditions for the gas chromatography analysis (GC analysis) performed in the examples and comparative examples are as follows:

<Analysis conditions>
Apparatus: Agilent-7890 (manufactured by Agilent)
Column: Inert Cap-1 (GL Sciences, length 60 m, inner diameter 0.25 mm, film thickness 1.5 μm)
Column temperature: 60° C. for 10 minutes, then heated to 260° C. at a rate of 20° C./min, and then held at 260° C. for 10 minutes. Injection temperature: 250° C.
Detector temperature: 250°C
Carrier gas: Nitrogen Split ratio: 100/1
Detector: FID

[Synthesis Example 1] Synthesis of α-chloroacrylic acid chloride 53.3 g (0.5 mol) of 2-chloroacrylic acid, 2 g of p-methoxyphenol, and 300 ml of methylene chloride were dissolved in a 1 L three-neck flask equipped with a condenser and a dropping funnel. The flask (reactor) was immersed in a water bath, the contents were stirred at room temperature, and 10 drops of N,N-dimethylformamide were added thereto. A solution of 82.5 g (0.65 mol) of oxalyl chloride dissolved in 100 ml of methylene chloride was dropped into the reactor from the dropping funnel over 2 hours. During that time, the gas generated by the reaction was led from the top of the condenser into a gas washing bottle containing 500 ml of water. After the dropping of oxalyl chloride was completed, the contents were stirred as it was for 1.5 hours, and then heated to 35°C in a water bath. About 40 minutes after the start of heating, the heating was stopped when the gas generation stopped and the system became negative pressure. Using a rotary evaporator, most of the methylene chloride and unreacted oxalyl chloride were distilled off from the content of the reactor while heating to 35° C. 1 g of p-methoxyphenol was added to the resulting residual liquid, and distillation was carried out under reduced pressure of 10 kPa. A fraction having a boiling point of 47 to 49° C. was collected to obtain 36 g of α-chloroacrylic acid chloride (yield: 57%).

[Synthesis Example 2] Production of α-bromoacrylic acid chloride 25 g (0.1 mol) of 2,3-dibromopropionic acid chloride and 120 ml of methylene chloride were placed in a 300 ml three-neck flask equipped with a condenser and a dropping funnel. The flask (reactor) was immersed in an ice water bath, and 15.2 g (0.15 mol) of triethylamine was dropped from the dropping funnel over 25 minutes while stirring the contents. 30 minutes after the end of the dropping, the reactor was removed from the ice water bath and stirred at room temperature for 1 hour. The salt generated by the reaction was removed by filtration under reduced pressure. Most of the methylene chloride was distilled off from the obtained filtrate while heating to 35°C using a rotary evaporator. The resulting residual liquid was distilled under a reduced pressure of 2 kPa, and a fraction having a boiling point of 39 to 40° C. was collected to obtain 12.5 g of α-bromoacrylic acid chloride (yield 74%).

[Example 1]
In a 200 ml round-bottom flask equipped with a dropping funnel and a stirrer, 10.36 g (0.075 mol) of potassium carbonate and 30 ml of water were placed and stirred to dissolve the potassium carbonate. The round-bottom flask was immersed in an ice-water bath, and 8.4 g (0.05 mol) of 1,1,1,3,3,3-hexafluoroisopropanol was added. After stirring for about 10 minutes, 30 ml of toluene and 0.8 g (0.0025 mol) of tetrabutylammonium bromide as a phase transfer catalyst were added and stirred vigorously. Next, 6.8 g (0.075 mol) of acrylic acid chloride was added dropwise from the dropping funnel over about 20 minutes. The contents were stirred as is for 30 minutes, and then stirred at 20°C for another 6 hours. The contents were transferred to a separatory funnel, and the aqueous phase was separated. The remaining water-immiscible organic solvent phase was washed with 20 ml of hydrochloric acid (concentration: 5% by mass), saturated sodium bicarbonate water, and saturated saline, and then dried with magnesium sulfate. Magnesium sulfate was removed by washing with a small amount of toluene, and 29.52 g of a toluene solution containing the product was obtained. When this solution was analyzed by gas chromatography using acrylic acid hexafluoroisopropyl ester as a standard substance, it contained 8.19 g of acrylic acid hexafluoroisopropyl ester (yield: 73.7%).

[Example 2]
Except for replacing all of the water-immiscible organic solvent toluene with cyclopentyl methyl ether, the same procedures as in Example 1 were carried out to obtain 26.67 g of a cyclopentyl methyl solution containing a product. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 7.12 g of hexafluoroisopropyl acrylate (yield: 64.1%).

[Example 3]
Except for changing the phase transfer catalyst tetrabutylammonium bromide 0.8 g (0.0025 mol) to benzyltriethylammonium chloride 0.57 g (0.0025 mol) in Example 1, various operations were carried out in the same manner as in Example 1 to obtain 28.46 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography, it was found to contain 7.92 g of hexafluoroisopropyl acrylate (yield: 71.3%).

[Example 4]
In Example 1, 0.8 g (0.0025 mol) of tetrabutylammonium bromide as a phase transfer catalyst was replaced with 0.43 g (0.0025 mol) of tetramethylammonium hydrogen sulfate, and the same procedures as in Example 1 were carried out to obtain 24.81 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography using acrylic acid hexafluoroisopropyl ester as a standard substance, it was found to contain 7.87 g of acrylic acid hexafluoroisopropyl ester (yield: 70.9%).

[Example 5]
In Example 1, 0.8 g (0.0025 mol) of tetrabutylammonium bromide as a phase transfer catalyst was replaced with 1.01 g (0.0025 mol) of triacrylmethylammonium chloride, and the same procedures as in Example 1 were carried out to obtain 25.85 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography using acrylic acid hexafluoroisopropyl ester as a standard substance, it was found to contain 6.73 g of acrylic acid hexafluoroisopropyl ester (yield: 60.6%).

[Example 6]
In Example 1, 0.8 g (0.0025 mol) of tetrabutylammonium bromide was replaced with 0.85 g (0.0025 mol) of tetrabutylammonium hydrogen sulfate as a phase transfer catalyst, and the same procedures as in Example 1 were carried out to obtain 27.37 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 8.38 g of hexafluoroisopropyl acrylate (yield: 75.5%).

[Example 7]
In Example 1, 0.8 g (0.0025 mol) of tetrabutylammonium bromide was replaced with 0.85 g (0.0025 mol) of tetrabutylphosphonium bromide as a phase transfer catalyst, and the same procedures as in Example 1 were carried out to obtain 25.96 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 6.64 g of hexafluoroisopropyl acrylate (yield: 59.8%).

[Example 8]
Except for changing 10.36 g (0.075 mol) of potassium carbonate to 5.83 g (0.075 mol) of sodium carbonate in Example 6, various operations were carried out in the same manner as in Example 6 to obtain 29.75 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 7.49 g of hexafluoroisopropyl acrylate (yield: 67.5%).

[Example 9]
Except for changing 10.36 g (0.075 mol) of potassium carbonate to 7.51 g (0.075 mol) of potassium hydrogen carbonate in Example 6, various operations were carried out in the same manner as in Example 6 to obtain 29.24 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 6.92 g of hexafluoroisopropyl acrylate (yield: 62.3%).

[Example 10]
Except for changing 10.36 g (0.075 mol) of potassium carbonate to 13.06 g (0.075 mol) of dipotassium hydrogen phosphate in Example 6, various operations were carried out in the same manner as in Example 6 to obtain 24.34 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 7.18 g of hexafluoroisopropyl acrylate (yield: 64.6%).

[Example 11]
Except for changing 10.36 g (0.075 mol) of potassium carbonate to 10.65 g (0.075 mol) of disodium hydrogen phosphate in Example 6, various operations were carried out in the same manner as in Example 6 to obtain 25.86 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 7.02 g of hexafluoroisopropyl acrylate (yield: 63.2%).

[Example 12]
Except for changing 10.36 g (0.075 mol) of potassium carbonate to 10.61 g (0.05 mol) of tripotassium phosphate in Example 6, various operations were carried out in the same manner as in Example 6 to obtain 30.05 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography, it was found to contain 7.48 g of hexafluoroisopropyl acrylate (yield: 67.3%).

[Example 13]
In Example 6, 6.8 g (0.075 mol) of acrylic acid chloride was changed to 7.8 g (0.075 mol) of methacrylic acid chloride, and all of the toluene, which is a water-immiscible organic solvent, was changed to p-xylene. The same procedures as in Example 6 were carried out to obtain 30.70 g of a p-xylene solution containing a product. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 9.826 g of hexafluoroisopropyl methacrylate (yield: 83.2%).

[Example 14]
Various operations were carried out in the same manner as in Example 13, except that 7.8 g (0.075 mol) of methacrylic acid chloride was changed to 9.38 g (0.075 mol) of 2-chloroacrylic acid chloride obtained in Synthesis Example 1, to obtain 29.44 g of a p-xylene solution containing a product. When this solution was analyzed by gas chromatography using α-chloroacrylic acid hexafluoroisopropyl ester as a standard substance, it was found to contain 8.78 g of α-chloroacrylic acid hexafluoroisopropyl ester (yield: 68.5%).

[Example 15]
Various operations were carried out in the same manner as in Example 13, except that 7.8 g (0.075 mol) of methacrylic acid chloride was changed to 12.76 g (0.075 mol) of 2-bromoacrylic acid chloride obtained in Synthesis Example 2, to obtain 30.29 g of a p-xylene solution containing a product. When this solution was analyzed by gas chromatography using α-bromoacrylic acid hexafluoroisopropyl ester as a standard substance, it was found to contain 9.54 g of α-bromoacrylic acid hexafluoroisopropyl ester (yield: 63.2%).

[Comparative Example 1]
In a 100 ml round-bottom flask equipped with a dropping funnel and a stirrer, 8.4 g (0.05 mol) of 1,1,1,3,3,3-hexafluoroisopropanol, 6.8 g (0.075 mol) of acrylic acid chloride, and 70 ml of dried cyclopentyl methyl ether were added and stirred. The reactor was cooled with ice water, and 6.0 g (0.075 mol) of pyridine was added using a dropping funnel over about 15 minutes, and the mixture was stirred for about 1 hour. The temperature of the reactor was then raised to 25°C, and stirring was continued for another 7 hours. The contents were transferred to a separatory funnel and washed with 40 ml of water, 30 ml of 5% hydrochloric acid, 30 ml of saturated sodium bicarbonate water, and 30 ml of saturated saline, in that order, and the organic phase was dried over magnesium sulfate. Magnesium sulfate was removed by washing with a small amount of cyclopentyl methyl ether, and 55.01 g of a cyclopentyl methyl ether solution containing the product was obtained. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 0.89 g of hexafluoroisopropyl acrylate (yield: 8.0%).

[Comparative Example 2]
Except for not adding the phase transfer catalyst tetrabutylammonium bromide, various operations were carried out in the same manner as in Example 1 to obtain 27.29 g of a toluene solution containing a product. When this solution was analyzed by gas chromatography using hexafluoroisopropyl acrylate as a standard substance, it was found to contain 5.38 g of hexafluoroisopropyl acrylate (yield: 34.7%).

As is clear from the results of the above Examples and Comparative Examples, the method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester of the present invention is a method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester in good yield with simple operations, and is industrially advantageous in terms of economic efficiency.

The present invention provides a method for producing unsaturated carboxylic acid hexafluoroisopropyl esters in good yield with simple operations and in an economically advantageous industrial manner.

Claims (4)

The following formula (1):
[In formula (1), X represents a hydrogen atom, a halogen atom, or a methyl group.]
A method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester represented by the following formula:
1,1,1,3,3,3-hexafluoroisopropanol,
The following formula (2):
[In formula (2), X is the same as X in formula (1), and Y represents a halogen atom selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.]
in a mixed solvent containing a water-immiscible organic solvent and water,
The method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester, wherein the mixed solvent contains at least one alkali metal salt selected from the group consisting of alkali metal carbonates, alkali metal hydrogen carbonates, alkali metal phosphates, and alkali metal hydrogen phosphates, and a phase transfer catalyst. 2. The method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester according to claim 1, wherein the phase transfer catalyst is at least one salt selected from the group consisting of alkyl ammonium halide salts and alkyl ammonium hydrogen sulfate salts. The method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester according to claim 1 or 2, wherein the unsaturated carboxylic acid halide represented by formula (2) is at least one compound selected from the group consisting of acrylic acid chloride, α-chloroacrylic acid chloride, and α-bromoacrylic acid chloride. The method for producing an unsaturated carboxylic acid hexafluoroisopropyl ester according to any one of claims 1 to 3, wherein X in formula (1) is a hydrogen atom, a chlorine atom, or a methyl group.