JP6786068B2 - Method for producing diol - Google Patents

Description

The present invention relates to a method for producing a diol from a saturated hydrocarbon or a derivative thereof.

Diols such as ethylene glycol (EG) and propylene glycol (PG) are used for various purposes such as polymer raw materials and moisturizers, and due to their high industrial applicability, they are industrialized by various methods. Manufactured in. For example, EG is synthesized by using ethylene as an unsaturated hydrocarbon as a starting material, producing ethylene oxide by a chlorohydrin method or a silver-catalyzed oxidation method, and hydrolyzing the ethylene oxide (Non-Patent Document 1).

However, in the chlorohydrin method, equimolar calcium chloride (CaCl ₂ ) is produced as a by-product of ethylene oxide, and the treatment cost is enormous. In the oxidation method using the silver catalyst, the silver catalyst is oxidized immediately, so that frequent regeneration treatment is required. In either method, ethylene, which is an unsaturated hydrocarbon (alkene), can only be used as a starting material, and the unsaturated hydrocarbon must be prepared by dehydrogenation of the saturated hydrocarbon (alkane). In addition, sulfuric acid is required to oxidize ethylene oxide, which raises the problem of heat of neutralization in addition to the danger of waste. The same applies not only to EG but also to other diols such as PG.

"New Industrial Chemistry-Aiming for Harmony with the Environment", edited by Ginya Adachi, Chiaki Iwakura, Akio Baba, Kagaku-Dojin, 2003

Therefore, an object of the present invention is to provide a method capable of easily producing a diol using saturated hydrocarbon or a derivative thereof as a starting material.

In order to achieve the above object, the method for producing a diol according to the present invention (hereinafter, may be simply referred to as "the method for producing the present invention") irradiates the reaction system with light in the presence of a raw material and chlorine radical dioxide. The reaction step comprises a reaction step, wherein the raw material is a saturated hydrocarbon or a derivative thereof, the reaction system is a reaction system containing an organic phase, the organic phase contains the raw material and the chlorine radicals, and the reaction step. In the above, the raw material is oxidized by the light irradiation to produce a diol of the raw material.

According to the production method of the present invention, a diol of the saturated hydrocarbon or its derivative can be easily produced by using the saturated hydrocarbon or its derivative as a raw material instead of the conventional unsaturated hydrocarbon.

FIG. 1 is an example of prediction based on the UCAM-B3LYP / 6-311 + G (d, p) def2TZV calculation result when the chlorine dioxide radical (ClO ₂ ^· ) is irradiated with light. FIG. 2 is a diagram schematically showing an example of a reaction step in the production method of the present invention. FIG. 3 is a graph showing the results of ^{1 1} HNMR of Example 1. FIG. 4 is a graph showing the results of ^{1 1} HNMR of Example 2. FIG. 5 is a graph showing the results of EPR showing the generation of chlorine dioxide radicals in the reaction system of Example 1.

In the production method of the present invention, for example, at least the organic phase is irradiated with light in the reaction step.

In the production method of the present invention, for example, the reaction system is a two-phase reaction system containing the organic phase and the aqueous phase.

In the production method of the present invention, for example, in the reaction step, the reaction system is a dispersion system, one of the organic phase and the aqueous phase is a dispersion medium, and the other is a dispersoid. Irradiate.

In the production method of the present invention, for example, in the reaction step, the dispersoid is dispersed in the dispersion medium by stirring the reaction system.

In the production method of the present invention, for example, the stirring method is at least one selected from the group consisting of rotation treatment with a stirrer, stirring treatment with a vortex mixer, and ultrasonic treatment.

In the production method of the present invention, for example, in the reaction step, the reaction system is irradiated with light while being brought into contact with air.

In the production method of the present invention, for example, in the reaction step, light is irradiated in a state where oxygen (O ₂ ) is dissolved in the aqueous phase.

In the production method of the present invention, for example, in the reaction step, the reaction is carried out in an atmosphere where the temperature is -100 to 200 ° C. and the pressure is 0.1 to 10 MPa. Alternatively, in the production method of the present invention, for example, the reaction is carried out in an atmosphere where the temperature is 0 to 40 ° C. and the pressure is 0.1 to 0.5 MPa.

The production method of the present invention includes, for example, a recovery step of recovering the diol after the reaction step, and the recovery step is a step of recovering the aqueous phase containing the diol from the reaction system. is there.

In the production method of the present invention, the organic phase contains, for example, an organic solvent. The organic solvent may be, for example, a hydrocarbon solvent, a halogenated solvent, or a fluorous solvent.

In the production method of the present invention, the saturated hydrocarbon may be, for example, a straight chain, a branched chain, or a cyclic hydrocarbon.

The production method of the present invention further includes, for example, a chlorine dioxide radical generation step of generating the chlorine dioxide radical.

In the production method of the present invention, for example, the reaction system may be a two-phase reaction system containing the organic phase and the aqueous phase. In this case, the production method of the present invention may further include a chlorine dioxide radical generation step of generating the chlorine dioxide radical, and in the chlorine dioxide radical generation step, the aqueous phase generates the chlorine dioxide radical. The chlorine dioxide radical may be generated from the source of the chlorine dioxide radical including the source. Further, in the chlorine dioxide radical generating step, e.g., wherein the source of chlorine dioxide radicals chlorite ions (ClO 2 ^_-) a, by the action of at least one Lewis acid and Bronsted acid to the chlorite ion The chlorine dioxide radical may be generated.

In the production method of the present invention, when the saturated hydrocarbon in the raw material is ethane, the diol is ethylene glycol (EG). When the saturated hydrocarbon is propane, the diol is propylene glycol, specifically 1,2-propanediol or 1,3-propanediol. The propylene glycol synthesized by the conventional method is 1,3-propanediol, but according to the present invention, for example, 1,2-propanediol can be synthesized.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following description.

(1) Saturated hydrocarbon or derivative thereof In the present invention, the compound used as a raw material is the saturated hydrocarbon or a derivative thereof. Hereinafter, the saturated hydrocarbon and the derivative may be collectively referred to as a raw material or a raw material compound.

The saturated hydrocarbon is a so-called alkane and is not particularly limited. The saturated hydrocarbon may be, for example, linear, branched, or cyclic (eg, cycloalkane). The saturated hydrocarbon has 2 or more carbon atoms, for example, 2 to 20, 2 to 6, 2 to 5, and 2 to 4. Specific examples of the saturated hydrocarbon include ethane, propane, n-butane, 2-methylpropane, n-pentane, n-hexane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, and methylcyclohexane. ..

In the present invention, the "derivative" of the saturated hydrocarbon is an organic compound containing a hetero element (elements other than carbon and hydrogen). The hetero element is not particularly limited, and examples thereof include oxygen (O), nitrogen (N), sulfur (S), and halogen. Examples of the halogen include fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and the like. The derivative may be, for example, an organic compound having a structure in which a hydrocarbon group is bonded to an arbitrary substituent or atomic group. The derivative may be, for example, a compound having a structure in which a plurality of hydrocarbon groups are bonded by an arbitrary atomic group, and the hydrocarbon group may be substituted with an arbitrary one or a plurality of substituents. It does not have to be. The hydrocarbon group is not particularly limited, and examples thereof include a monovalent or divalent or higher valent group derived from the hydrocarbon. The hydrocarbon group may have, for example, one or two or more carbon atoms replaced with heteroatoms. The substituent or atomic group is not particularly limited, and examples thereof include a hydroxy group and a halogen group (fluoro group, chloro group, bromo group, iodo group, etc.).

When the raw material compound in the present invention contains isomers such as tautomers or stereoisomers (for example, geometric isomers, constitutive isomers and optical isomers), any isomer is not specified unless otherwise specified. Can also be used as a raw material of the present invention.

When the raw material compound can form a salt, the salt can also be used as a raw material of the present invention unless otherwise specified. The salt may be, for example, an acid addition salt or a base addition salt. The acid forming the acid addition salt may be, for example, an inorganic acid or an organic acid, and the base forming the base addition salt may be, for example, an inorganic base or an organic base. The inorganic acid is not particularly limited, and is, for example, sulfuric acid, phosphoric acid, hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodite, hypofluorous acid, hypochlorous acid, hypobromine acid, the following. Hypoiodous acid, chlorofluorous acid, chlorous acid, bromine acid, hypoiodous acid, fluoric acid, chloric acid, bromic acid, iodic acid, perfluoric acid, perchloric acid, perbromic acid, periodous acid, etc. can give. The organic acid is not particularly limited, and examples thereof include p-toluenesulfonic acid, methanesulfonic acid, oxalic acid, p-bromobenzenesulfonic acid, carbonic acid, succinic acid, citric acid, benzoic acid and acetic acid. The inorganic base is not particularly limited, and examples thereof include ammonium hydroxide, alkali metal hydroxide, alkaline earth metal hydroxide, carbonate, and hydrogen carbonate. Specific examples thereof include hydroxide. Examples thereof include sodium, potassium hydroxide, potassium carbonate, sodium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, calcium hydroxide and calcium carbonate. The organic base is not particularly limited, and examples thereof include ethanolamine, triethylamine, tris (hydroxymethyl) aminomethane, and the like. These salts are not particularly limited, and can be prepared, for example, by appropriately adding the above-mentioned acid or base to the raw material compound by a known method.

(2) Chlorine Dioxide Radical In the production method of the present invention, the chlorine dioxide radical is contained in the organic phase of the reaction system. The chlorine dioxide radical may be contained in the organic phase by being generated in the reaction system, for example, or a separately generated chlorine dioxide radical may be contained in the organic phase. The method for generating chlorine dioxide radicals is not particularly limited. Specific examples of the generation of chlorine dioxide radicals will be described later.

(3) Reaction system As described above, the reaction system contains an organic phase. The reaction system may be, for example, a one-phase reaction system containing only an organic phase, or a two-phase reaction system containing an organic phase and an aqueous phase.

(3-1) Organic Phase The organic phase contains the raw material compound and the chlorine dioxide radical as described above. The organic phase is, for example, a phase of an organic solvent containing the raw material compound and the chlorine dioxide radical.

The organic solvent is not particularly limited. As the organic solvent, for example, only one type may be used, or a plurality of types may be used in combination. In the present invention, examples of the organic solvent include hydrocarbon solvents, halogenated solvents, fluorous solvents and the like, as described above. When the reaction system is the two-phase reaction system, the organic solvent may be, for example, a solvent that can form the two-phase system, that is, a solvent that separates from the aqueous solvent that constitutes the aqueous phase, which will be described later, or the aqueous solvent. A poorly soluble or insoluble solvent is preferred.

The hydrocarbon solvent is not particularly limited, and examples thereof include n-hexane, cyclohexane, benzene, toluene, o-xylene, m-xylene, and p-xylene. The hydrocarbon solvent may also serve as, for example, the raw material compound (the hydrocarbon or a derivative thereof).

"Halogenation solvent" refers to, for example, a solvent in which all or most of the hydrogen atoms of a hydrocarbon are substituted with halogen. The halogenated solvent may be, for example, a solvent in which 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the number of hydrogen atoms of the hydrocarbon is substituted with halogen. The halogenated solvent is not particularly limited, and examples thereof include methylene chloride, chloroform, carbon tetrachloride, carbon tetrabromide, and a fluorous solvent described later.

The "fluorous solvent" is one of the halogenated solvents, for example, a solvent in which all or most of the hydrogen atoms of a hydrocarbon are substituted with fluorine atoms. The fluorous solvent may be, for example, a solvent in which 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the number of hydrogen atoms in the hydrocarbon is substituted with fluorine atoms. In the present invention, the use of the fluorous solvent has an advantage that, for example, the reactivity of the solvent itself is low, so that side reactions can be further suppressed or prevented. The side reactions include, for example, an oxidation reaction of the solvent, a hydrogen abstraction reaction or a chlorination reaction of the solvent by the chlorine dioxide radical, and a reaction of a radical derived from the raw material compound with the solvent (for example, the raw material compound In the case of ethane, the reaction between the ethane radical and the solvent) and the like can be mentioned. Since the fluorous solvent is immiscible with water, it is suitable for forming the two-phase reaction system, for example. Further, for example, when the diol compound which is a reaction product is recovered in the aqueous phase, the organic phase of the fluorous solvent and the aqueous phase can be easily separated. Therefore, the chlorine dioxide radical in the organic phase causes the diol compound. However, it is possible to sufficiently suppress the further oxidation reaction.

Examples of the fluorous solvent include, for example, solvents represented by the following chemical formulas (F1) to (F6), and among them, for example, CF ₃ (CF ₂ ) ₄ CF of n = 4 in the following formula (F1). ₃ etc. is preferable.

The boiling point of the organic solvent is not particularly limited. The organic solvent can be appropriately selected depending on, for example, the temperature conditions of the reaction step. When the reaction temperature is set to a high temperature in the reaction step, a high boiling point solvent can be selected as the organic solvent. The production method of the present invention does not necessarily require heating, as will be described later, and can be performed, for example, at normal temperature and pressure. In such a case, the organic solvent does not have to be, for example, a high boiling point solvent, and a solvent having a not so high boiling point can be used from the viewpoint of ease of handling.

In the organic phase, the concentration of the raw material compound is not particularly limited, and the lower limit is, for example, 0.0001 mol / L or more, and the upper limit is, for example, 60 mol / L or less.

The organic phase may contain, for example, only the raw material compound, the chlorine dioxide radical, and the organic solvent, or may further contain other components. The other components are not particularly limited, and examples thereof include Bronsted acid, Lewis acid, and oxygen (O ₂ ). In the organic phase, the raw material compound and any other component may be, for example, dissolved in the organic solvent or undissolved. In the latter case, the raw material compound and any of the other components may be, for example, dispersed or precipitated in the organic solvent.

The organic phase contains the chlorine dioxide radical as described above. The chlorine dioxide radical can be contained in the organic phase, for example, by generating it in a phase other than the organic phase and extracting it from the organic phase. That is, when the reaction system is a one-phase reaction system containing only an organic phase, for example, the chlorine dioxide radical is separately generated in a reaction system other than the organic phase, and the generated radical is used as the organic phase. The organic phase containing the radical dioxide radicals extracted by the above can be used as the reaction system in the reaction step. The generation of radical dioxide can be carried out, for example, in a separately prepared aqueous phase as described later. On the other hand, when the reaction system is a two-phase reaction system containing the organic phase and the aqueous phase, for example, in the aqueous phase, the chlorine dioxide radical is generated, and the generated chlorine radical is used as the organic phase. The aqueous phase and the organic phase containing chlorine dioxide radicals can be subjected to the reaction step as the two-phase reaction system.

(3-2) Aqueous phase The aqueous phase is, for example, a phase of an aqueous solvent. The aqueous solvent is, for example, a solvent that separates from the solvent used in the organic phase. Examples of the aqueous solvent include water such as H ₂ O and D ₂ O.

The aqueous phase may contain, for example, any component such as Lewis acid, Bronsted acid, radical source, etc., as described below. In the aqueous phase, these arbitrary components may be, for example, dissolved in the aqueous solvent or not dissolved. In the latter case, the optional component may be, for example, dispersed in the aqueous solvent or precipitated.

(4) Reaction Step In the present invention, the reaction step is a step of irradiating the reaction system with light in the presence of the raw material and the chlorine dioxide radical. As described above, in the reaction system, the organic phase contains the raw material and the chlorine dioxide radical.

When the raw material and the organic phase containing the chlorine dioxide radical (ClO ₂ ^· ) are irradiated with light in the reaction step, the light-irradiated chlorine dioxide radical is predicted to be as shown in FIG. 1, for example. FIG. 1 shows the calculation result by UCAM-B3LYP / 6-311 + G (d, p) def2TZV. In FIG. 1, the left side represents the state of chlorine dioxide radical (ClO ₂ ^· ) molecules before light irradiation, and the right side represents the state after light irradiation. As shown in FIG. 1, two oxygen atoms O are bonded to the chlorine atom Cl before light irradiation, and the bond length of Cl—O is 1.502 Å (0.1502 nm). On the other hand, after light irradiation, only one oxygen atom O is bonded to the chlorine atom Cl, the bond length of Cl—O is 2.516 Å (0.2516 nm), and the other oxygen atom is one of the above. It becomes a state of being bonded to the oxygen atom of. It is considered that this cleaves the Cl—O bond and generates chlorine radicals (Cl ^· ) and oxygen molecules (O ₂ ). The chlorine radical acts as a hydrogen abstractor with respect to the raw material, and the oxygen molecule acts as an oxidizing agent. Therefore, the chlorine radical abstracts hydrogen from the raw material to generate a radical derived from the raw material, and further, the oxygen molecule oxidizes the radical derived from the raw material to generate a diol. FIG. 1 is an example of prediction based on a calculation result, and does not limit the present invention in any way.

In the reaction step, for example, when the raw material is ethane, ethylene glycol (ethanediol) is produced as a diol, and when the raw material is propane, propylene glycol is produced as a diol. In the reaction system, an oxide of the raw material may be contained in addition to the diol.

In the reaction step, the conditions of light irradiation are not particularly limited. The wavelength of the irradiation light is not particularly limited, the lower limit is, for example, 200 nm or more, the upper limit is, for example, 800 nm or less, the light irradiation time is not particularly limited, and the lower limit is, for example, 1 minute or more. Yes, the upper limit is, for example, 1000 hours, the reaction temperature is not particularly limited, the lower limit is, for example, 0 ° C. or higher, and the upper limit is, for example, 100 ° C. or lower. The atmospheric pressure during the reaction is not particularly limited, and the lower limit is, for example, 0.1 MPa or more, and the upper limit is, for example, 100 MPa or less. Examples of the reaction conditions in the reaction step include a temperature of 0 to 40 ° C. and a pressure of 0.1 to 0.5 MPa. According to the present invention, for example, the reaction step or all steps including the reaction step can be carried out at normal temperature (room temperature) and normal pressure (atmospheric pressure) without heating, pressurizing, depressurizing or the like. .. The “room temperature” is not particularly limited, and is, for example, 5 to 35 ° C. Further, according to the present invention, for example, the reaction step or all the steps including the reaction step can be carried out in the atmosphere without performing the inert gas substitution or the like.

The light source for light irradiation is not particularly limited, and for example, visible light contained in natural light such as sunlight can be used. If natural light is used, for example, excitation can be easily performed. Further, as the light source, for example, instead of the natural light or in addition to the natural light, a light source such as a xenon lamp, a halogen lamp, a fluorescent lamp, or a mercury lamp can be used. In the light irradiation, for example, a filter that cuts wavelengths other than the required wavelength can be appropriately used.

As described above, the reaction system may be, for example, a one-phase reaction system composed of only the organic phase, or a two-phase reaction system including the organic phase and the aqueous phase system. In the former case, for example, the reaction step can be carried out by irradiating the one-phase reaction system with light. In the latter case, for example, only the organic phase may be irradiated with light, or the two-phase reaction system may be irradiated with light to irradiate the organic phase with light to carry out the reaction step.

When the reaction system is the two-phase reaction system, light irradiation can be performed as follows, for example.

When the light irradiation is performed, for example, in the reaction system, the organic phase and the aqueous phase are separated from each other to form two layers, an organic layer and an aqueous layer, and even if they are in contact with each other only at the interface. Good. Further, when the light irradiation is performed, the reaction system is, for example, a dispersion system in which one of the organic phase and the aqueous phase is dispersed, and the dispersion system may be irradiated with light. From the viewpoint of reaction efficiency, for example, the latter is preferable. When the reaction system is the dispersion system, for example, one of the organic phase and the aqueous phase can be said to be a dispersion medium, and the other can be said to be a dispersoid. The dispersion system can also be referred to as an emulsion, for example.

When the reaction system is the dispersion system, the dispersoid can be dispersed in the dispersion medium in the reaction step, for example, by stirring the reaction system. The method of stirring is not particularly limited, and examples thereof include a stirring process of rotating the reaction system using a stirrer, a stirring process of rotating the reaction system using a vortex mixer, and an ultrasonic treatment. Be done. The stirring conditions are not particularly limited. The rotation speed in the stirring is preferably 2,600 rpm or more, for example.

When the reaction system is the two-phase reaction system, if the diol produced in the reaction step is water-soluble, for example, the produced diol dissolves in the aqueous phase and is water-insoluble or sparingly water-soluble. If it is of sex, for example, the produced diol is dissolved in the organic phase. When the diol is ethylene glycol or propylene glycol, for example, the diol dissolves in the aqueous phase. Examples of the water-soluble diol form include 2 to 6, 2 to 5, 2 to 4 carbon atoms.

In the reaction step, it is preferable that the reaction system is irradiated with light, for example, in a state where oxygen is dissolved in the reaction system. When the reaction system is the one-phase system, for example, oxygen is dissolved in the organic phase, and when the reaction system is the two-phase system, for example, oxygen is contained in at least one of the organic phase and the aqueous phase. It is dissolved, preferably oxygen is dissolved in the aqueous phase. Specific examples of the light irradiation under the above conditions include a method of irradiating the reaction system with light while in contact with air or oxygen gas, a method of irradiating light while introducing air or oxygen gas into the reaction system, and the like. can give. The former method can be carried out, for example, by stirring the reaction system as described above. The latter method can be carried out, for example, by inserting the tip of a tube or the like into the reaction system and sending air or oxygen through the tube. When the reaction system contains oxygen, for example, the oxidation reaction of the raw material can be further promoted.

According to the present invention, in the reaction step, in a very simple method that only the light irradiation in the presence of the chlorine dioxide radicals to generate a chlorine atom radical Cl ^· and molecular oxygen O _2, the oxidation reaction to the raw material The above-mentioned diol can be obtained. Then, for example, even under extremely mild conditions such as normal temperature and pressure, the raw material can be efficiently oxidized and converted into the diol by such a simple method.

According to the present invention, for example, the diol can be obtained from the raw material without using a toxic heavy metal catalyst or the like. Therefore, as described above, the reaction can be carried out under extremely mild conditions, and the diol can be efficiently obtained by a method having an extremely small burden on the environment.

(5) Recovery Step The present invention may further include a recovery step of the diol after the reaction step. Examples of the recovery step include a step of recovering the aqueous phase containing the diol from the reaction system. When the diol is, for example, a diol that is easily dissolved in an aqueous solvent, recovery by the aqueous phase is preferable. When the reaction system is a one-phase reaction system composed of the organic phase, for example, after the reaction step, the reaction system and the aqueous solvent are mixed, and the diol contained in the reaction system is transferred to the aqueous phase. .. Then, the diol can be recovered by separating the organic phase and the aqueous phase into two layers and recovering the aqueous phase. When the reaction system is a two-phase reaction system, for example, after the reaction step, the reaction system is separated into two layers, the organic phase and the aqueous layer, and the aqueous phase is recovered to obtain the diol. Can be recovered.

The recovery step is not limited to the above example, and may be, for example, a step of recovering the organic phase containing the diol from the reaction system. When the diol is, for example, a diol that is sparingly soluble in an aqueous solvent and easily soluble in an organic solvent, recovery by the organic phase is preferable. When the reaction system is a one-phase reaction system composed of the organic phase, the diol can be recovered, for example, by recovering the reaction system after the reaction step. When the reaction system is a two-phase reaction system, for example, after the reaction step, the reaction system is separated into two layers, the organic phase and the aqueous layer, and the organic phase is recovered to obtain the diol. Can be recovered.

The recovery step may be, for example, a step of filtering the reaction system or the like to recover the diol. When the diol is sparingly soluble in both an aqueous solvent and an organic solvent, recovery by filtration or the like is preferable.

(6) Purification Step The production method of the present invention may further include, for example, a purification step of isolating and purifying the recovered diol. The method for isolation and purification is not particularly limited, and for example, a method such as distillation or filtration can be appropriately adopted depending on the type of the diol, the type of the reaction system, and the like.

(6) Chlorine Dioxide Radical Generation Step The production method of the present invention may further include, for example, a chlorine dioxide radical generation step of generating the chlorine dioxide radical. In the production method of the present invention, the radical dioxide generation step can be performed, for example, before the reaction step or at the same time as the reaction step. The method for producing the chlorine dioxide radical is not particularly limited.

When the reaction system is a two-phase reaction system containing the organic phase and the aqueous phase as described above, for example, the aqueous phase contains the source of the chlorine dioxide radical and the chlorine dioxide radical generation step. In, the chlorine dioxide radical may be generated from the source of the chlorine dioxide radical. The aqueous phase is, for example, a phase of an aqueous solvent containing the source of the chlorine dioxide radical, and the aqueous solvent is the same as described above.

The source of the chlorine dioxide radical is not particularly limited, and is, for example, chlorous acid (HClO ₂ ) or a salt thereof. The salt of chlorous acid is not particularly limited, and examples thereof include metal salts. Examples of the metal salt include alkali metal salts, alkaline earth metal salts, rare earth salts and the like. Specific examples thereof include sodium chlorite (NaClO ₂ ), lithium chlorite (LiClO ₂ ) and subchlorite. Examples thereof include potassium chlorite (KClO ₂ ), magnesium chlorite (Mg (ClO ₂ ) ₂ ), calcium chlorite (Ca (ClO ₂ ) ₂ ) and the like. As the source of the chlorine dioxide radical, for example, only one type may be used, or a plurality of types may be used in combination. Among these, sodium chlorite (NaClO ₂ ) is preferable from the viewpoint of cost, ease of handling, and the like.

In the aqueous phase, the concentration of the source is not particularly limited. The concentration of the source is chlorite ions (ClO ₂ ^-) when converted to a concentration, for example, the lower limit is at 0.0001 mol / L or more, and the upper limit is, at 1 mol / L or less. The concentration of the source, the chlorite ions (ClO ₂ ^-) when converted to the number of moles of, for example, lower limit is at 1/100000 times the number of moles of the raw material, the upper limit is 1000 It is less than double.

The aqueous phase may further contain, for example, at least one of Lewis acid and Bronsted acid. The aqueous layer may contain, for example, only one of the Lewis acid and the Bronsted acid, or both, and one substance serves as both the Lewis acid and the Bronsted acid. May be good. Only one type of the Lewis acid or the Bronsted acid may be used, or a plurality of types may be used in combination. In the present invention, "Lewis acid" refers to, for example, a substance that acts as Lewis acid with respect to the chlorine dioxide radical generation source.

In the aqueous phase, the concentration of at least one of the Lewis acid and the Bronsted acid is not particularly limited, and can be appropriately set depending on, for example, the type of the raw material and the diol produced. The lower limit of the concentration is 0.0001 mol / L or more, and the upper limit is 1 mol / L or less.

The Lewis acid is not particularly limited, and may be, for example, an organic substance or an inorganic substance. Examples of the organic substance include ammonium ions and organic acids (for example, carboxylic acids). Examples of the inorganic substance include metal ions and non-metal ions, and either one may be contained or both may be contained. Examples of the metal ion include a typical metal ion and a transition metal ion, and may contain either one or both. The inorganic substances include, for example, alkaline earth metal ions (for example, Ca ²⁺ ), rare earth ions, Mg ²⁺ , Sc ³⁺ , Li ⁺ , Fe ²⁺ , Fe ³⁺ , Al ³⁺ , silicate ions, borate ions and the like. However, any one type may be contained, or two or more types may be contained. Examples of the alkaline earth metal ion include ions such as calcium, strontium, barium, and radium, and specific examples thereof include Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , and Ra ²⁺ . "Rare earths" is a general term for a total of 17 elements, including two elements, scandium ₂₁ Sc and yttrium ₃₉ Y, and 15 elements (lanthanoids) from lanthanum ₅₇ La to lutetium ₇₁ Lu. Examples of rare earth ions include trivalent cations for each of the 17 elements. The counter ion of the Lewis acid is not particularly limited, and is, for example, trifluoromethanesulfonic acid ion (also referred to as CF ₃ SO ₃ ⁻ or OTf ⁻ ), trifluoroacetate ion (CF ₃ COO ⁻ ), acetate ion, and foot. Examples thereof include compound ion, chloride ion, bromide ion, iodide ion, sulfate ion, hydrogen sulfate ion, sulfite ion, nitrate ion, nitrite ion, phosphate ion and phosphite ion. The Lewis acid may be, for example, scandium triflate (Sc (OTf) ₃ ) or the like.

Examples of the Lewis acid (including counter ions) include AlCl ₃ , AlMeCl ₂ , AlMe ₂ Cl, BF ₃ , BPh ₃ , BMe ₃ , TiCl ₄ , SiC ₄ , SiCl ₄ , and any one of them. It may contain two or more types. "Ph" represents a phenyl group and "Me" represents a methyl group.

The Lewis acidity of the Lewis acid is not particularly limited, and is, for example, 0.4 eV or more. The upper limit of the Lewis acidity is not particularly limited, and is, for example, 20 eV or less. The Lewis acidity is, for example, Ohkubo, K .; Fukuzumi, S. Chem. Eur. J., 2000, 6, 4532, J. AM. CHEM. SOC. 2002, 124, 10270-10271, or J. Org. It can be measured by the method described in Chem. 2003, 68, 4720-4726, and specifically, it can be measured by the following method.

(Measurement method of Lewis acidity)
Cobalt tetraphenylporphyrin (CoTPP) saturated O ₂ represented by the following chemical reaction formula (1a) and an object for measuring Lewis acidity (for example, a cation such as a metal, which is represented by M ^{n +} in the following chemical reaction formula (1a)). For acetonitrile (MeCN) containing (), the change in ultraviolet-visible absorption spectrum is measured at room temperature. From the obtained reaction rate constant (k _cat ), the ΔE value (eV), which is an index of Lewis acidity, can be calculated. The larger the k- _cat value, the stronger the Lewis acidity. The Lewis acidity of an organic compound can also be estimated, for example, from the energy level of the lowest empty orbital (LUMO) calculated by quantum chemistry calculations. As for the energy rank, the larger the value on the positive side, the stronger the Lewis acidity.

The brainstead acid is not particularly limited, and may be, for example, an inorganic acid or an organic acid. Specific examples thereof include trifluoromethanesulfonic acid, trifluoroacetic acid, acetic acid, hydrofluoric acid, and hydrochloride. Examples thereof include hydrobromic acid, hydroiodic acid, sulfuric acid, sulfite, nitric acid, nitrite, phosphoric acid, and phosphite. Acid dissociation constant pK _a of the Bronsted acids are, for example, 10 or less. The lower limit of pK _a is not particularly limited, and is, for example, −10 or more.

The aqueous phase, for example, chlorite ion (ClO 2 ^_-) include and the Bronsted acids, for example, the sodium chlorite (NaClO ₂₎ and Bronsted acids (e.g. hydrochloric acid) is dissolved in an aqueous solvent It is preferably an aqueous phase.

In the aqueous phase, for example, the Lewis acid, the Bronsted acid, the radical source, and the like may or may not be dissolved in the aqueous solvent. In the latter case, they may be, for example, dispersed in an aqueous solvent or precipitated.

The aqueous phase is preferably in a state in which oxygen (O ₂ ) is dissolved, for example. The dissolution of the oxygen (O ₂ ) in the aqueous phase is not particularly limited, and may be, for example, before or after the generation of chlorine dioxide radicals, or before or during the reaction step. Specific examples include, for example, air or oxygen in at least one of the aqueous phase and the organic phase before or after adding the chlorine dioxide radical generation source, the Lewis acid, the brainstead acid, the raw material, and the like. Oxygen may be dissolved by blowing a gas. The aqueous phase may be saturated with oxygen (O ₂ ), for example.

The chlorine dioxide radical generation step is not particularly limited, and for example, by including the source of the chlorine dioxide radical in the aqueous solvent, chlorine dioxide radical can be spontaneously generated from the chlorite ion. In the aqueous phase, for example, the source is preferably dissolved in the aqueous solvent, and the aqueous phase is preferably allowed to stand. In the chlorine dioxide radical generation step, the aqueous phase can further promote the generation of chlorine dioxide radicals, for example, by coexisting at least one of the Lewis acid and the Bronsted acid. In the chlorine dioxide radical generation step, for example, the chlorine dioxide radical can be generated by irradiating the aqueous phase with light, but chlorine dioxide can be generated without light irradiation, for example, simply by allowing it to stand. Radicals can be generated. Since the radical dioxide generated from the source in the aqueous phase in the reaction system is sparingly soluble in water, it dissolves in the organic phase in the reaction system.

The mechanism by which chlorine dioxide radicals are generated from chlorite ions in the aqueous phase is presumed, for example, as in Scheme 1 below. Scheme 1 below is an example of a speculated mechanism and does not limit the present invention in any way. In Scheme 1 below, the first (upper) reaction schemes, chlorite ions (ClO 2 ^_-) a disproportionation reaction, that at least one of Lewis acids and Bronsted acids in the aqueous phase is present , It is thought that the equilibrium tends to move to the right. In the following scheme 1, the second (middle) reaction formula is a dimerization reaction, in which the hypochlorite ion (ClO ⁻ ) generated by the first reaction formula reacts with the chlorite ion. , Produces dichlorine dioxide (Cl ₂ O ₂ ). It is considered that this reaction is more likely to proceed as the aqueous phase has more protons H ⁺ , that is, the more acidic it is. In Scheme 1 below, the third (lower) reaction equation is radical generation. In this reaction, dichlorine dioxide produced by the second reaction formula reacts with chlorite ions to generate chlorine dioxide radicals.

When the reaction system is a two-phase reaction system containing the organic phase and the aqueous phase, after generating the chlorine dioxide radical as described above, the reaction system is directly subjected to the above reaction step. do it. That is, it is also possible to carry out the reaction step of producing a diol by further irradiating the reaction system in which the chlorine dioxide radical is generated with light. In this case, for example, by irradiating the reaction system with light, the chlorine dioxide radical generation step and the reaction step can be continuously performed. In the production method of the present invention, by carrying out the reaction step in a two-phase reaction system of the aqueous phase and the organic phase, for example, the water-soluble diol can be easily recovered from the aqueous phase. You can also do it. Further, by performing the chlorine dioxide radical generation step and the reaction step in the two-phase reaction system, for example, better reaction efficiency can be obtained.

On the other hand, when the reaction system in the above-mentioned reaction step is a one-phase reaction system containing only the organic phase, for example, the chlorine radicals are generated in the aqueous phase by the method, and the generated chlorine radicals are generated. After dissolving (extracting) in the organic phase, the aqueous phase may be removed, and the organic phase containing the chlorine dioxide radical may be used as the one-phase reaction system for the reaction step.

FIG. 2 schematically shows an example of the chlorine dioxide radical generation step and the reaction step using the two-phase reaction system. As shown in FIG. 2, in the reaction system, two layers, an aqueous layer (the aqueous phase) and an organic layer (the organic phase), are separated in the reaction vessel and are in contact with each other only at the interface. The upper layer is the aqueous layer (the aqueous phase) 2, and the lower layer is the organic layer (the organic phase) 1. FIG. 2 is a cross-sectional view, but the hatches of the aqueous layer 2 and the organic layer 1 are omitted for the sake of clarity. As shown in FIG. 2, the aqueous layer (aqueous phase) in 2 chlorite ion (ClO ₂ ^-) reacts with the acid, chlorine dioxide radical (ClO ₂ ^·) is generated. Since the chlorine dioxide radical (ClO ₂ ^· ) is sparingly soluble in water, it dissolves in the organic layer 1. Next, the chlorine dioxide radicals in the organic layer 1 are irradiated by irradiating the organic layer 1 containing chlorine dioxide radicals (ClO ₂ ^· ) with light energy hν (h is the Planck constant and ν is the frequency of light). (ClO ₂ ^· ) is decomposed to generate chlorine radicals (Cl ^· ) and oxygen molecules (O ₂ ). As a result, the raw material (represented by the symbol RH in the figure) in the organic layer (organic phase) 1 is oxidized to generate a diol (represented by the symbol OH-R-OH in the figure) which is an oxidation reaction product. .. Since the diol is generally water-soluble, it dissolves in the aqueous layer 2. FIG. 2 is an example and does not limit the present invention in any way.

In FIG. 2, the aqueous layer 2 is the upper layer and the organic layer 1 is the lower layer. For example, when the organic layer 1 has a lower density (specific gravity), the organic layer 1 becomes the upper layer. Further, the production method of the present invention is not limited to the layer-separated state as shown in FIG. 2, and may be carried out in a dispersed state such as an emulsion as described above, or may be stirred or the like. You can also do it while doing it.

Although the two-phase reaction system is illustrated in FIG. 2, in the production method of the present invention, the reaction step may be carried out in a one-phase reaction system containing only an organic phase. In this case, for example, an aqueous phase containing the source of the chlorine dioxide radical is separately prepared, chlorine dioxide radicals are generated in the aqueous phase, and then the organic phase is mixed with the aqueous phase to obtain the said aqueous phase. Chlorine dioxide radicals are dissolved (extracted) in the organic phase. The raw material may be added to the organic phase prior to the extraction of the chlorine dioxide radical, or may be added to the organic phase at the same time as the extraction of the chlorine dioxide radical, or the chlorine dioxide radical may be added. After extraction, it may be added to the organic phase. Then, the aqueous phase and the organic phase are separated, the organic phase is recovered, and this is used alone as a one-phase reaction system in the presence of the raw material and the chlorine dioxide radical, and the reaction step by light irradiation. To do.

Hereinafter, examples of the present invention will be described. However, the present invention is not limited to the following examples.

[Examples 1 and 2]
Saturated hydrocarbons (alkanes) were dissolved in a fluorous solvent to prepare an organic phase. On the other hand, sodium chlorite (NaClO ₂ ), which is the source of the radical dioxide, and HCl, which is an acid, are dissolved in an aqueous solvent, and the obtained aqueous solution is saturated with oxygen gas (O ₂ ) to prepare an aqueous phase. did. The aqueous phase and the organic phase were placed in the same reaction vessel and brought into contact with each other to form a two-phase reaction system. Further, in the air, the two-phase reaction system is not pressurized or depressurized, and under room temperature (about 25 ° C.) conditions, a xenon lamp having a wavelength of λ> 290 nm (Ushio 500 W, Pyrex® glass filler) It was irradiated with light. The light irradiation was carried out while the reaction vessel was placed in a vortex mixer (product name: test tube mixer, manufacturer AS ONE) for 3 minutes. The rotation speed of the vortex mixer was set to 2,600 rpm. In this way, a diol was produced from the saturated hydrocarbon.

The conditions in each of Examples 1 and 2 are shown in Table 1 below. The yield of the diol and the light irradiation time are also shown in Table 1 below. In Tables 1 and 2 below, "D" represents deuterium. The conversion rate of the saturated hydrocarbon and the yield of the diol were calculated by measuring ¹ HNMR of the saturated hydrocarbon before the reaction and the diol after the reaction, respectively, and comparing the peak intensity ratios of each component. The results of ^{1 1} HNMR in Examples 1 and 2 are shown in FIGS. 3 and 4.

As shown in Table 1 and FIG. 3, in Example 1, 1,2-ethanediol (EG) was obtained from ethane in a yield of 11%, and the reaction time was extremely short, with a light irradiation time of 3 minutes. Met. Further, as shown in Table 1 and FIG. 4, in Example 2, 1,2-propanediol (PG) was obtained from propane in a yield of 25%, and the reaction time was extremely high, with a light irradiation time of 3 minutes. It was a short time.

In the conventional synthesis method, an alkene can be used as a starting material, and there is no method for synthesizing a diol using an alkane as a starting material. Therefore, it was found that a diol can be easily produced from an alkane according to the present invention. Further, according to the present invention, a diol can be easily produced only by irradiating with light.

In Examples 1 and 2, chlorine dioxide radicals were generated in the two-phase reaction system, and diols were further generated by oxidation. The generation of chlorine dioxide radicals in the reaction system has been confirmed by EPR (electron spin resonance). The result of the EPR is shown in FIG.

As described above, according to the production method of the present invention, a diol of the saturated hydrocarbon or its derivative can be easily produced by using the saturated hydrocarbon or its derivative as a raw material instead of the conventional unsaturated hydrocarbon. According to the present invention, the saturated hydrocarbon or a derivative thereof can be efficiently converted into a diol by an extremely simple method of only irradiating with light, for example, even under extremely mild conditions such as normal temperature and normal pressure. It is possible. According to the present invention, for example, various diols having extremely high industrial applicability can be efficiently obtained by using the saturated hydrocarbon or a derivative thereof as a raw material. Conventionally, such a diol cannot be efficiently obtained from a saturated hydrocarbon as a raw material, so that it is difficult to effectively use a hydrocarbon such as natural gas as a raw material. On the other hand, according to the present invention, hydrocarbons such as natural gas can be effectively used as a raw material. Therefore, according to the present invention, a compound that had to be synthesized using petroleum or the like as a raw material can be synthesized extremely easily and efficiently using natural gas or the like as a raw material, which makes a great contribution to energy problems and the like. It is possible. Further, according to the present invention, for example, a diol of the saturated hydrocarbon or a derivative thereof can be obtained without using a toxic heavy metal catalyst or the like. According to this, as described above, for example, the reaction can be carried out under extremely mild conditions such as normal temperature and pressure, and the diol can be efficiently obtained by a method having an extremely small burden on the environment. Is. As described above, the industrial applicability of the present invention is enormous.

1 Organic layer (organic phase)
2 Water layer (water phase)

Claims (18)

Including a reaction step of irradiating the reaction system with light in the presence of raw materials and chlorine dioxide radicals.
The raw material is a saturated hydrocarbon or a derivative thereof.
The reaction system is a reaction system containing an organic phase.
The organic phase contains the raw material and the chlorine dioxide radicals.
A method for producing a diol, which comprises oxidizing the raw material by the light irradiation in the reaction step to produce a diol as an oxidation reaction product of the raw material. The production method according to claim 1, wherein at least the organic phase is irradiated with light in the reaction step. The production method according to claim 1 or 2, wherein the reaction system is a two-phase reaction system containing the organic phase and the aqueous phase. In the reaction step
The reaction system is a dispersion system and
One of the organic phase and the aqueous phase is a dispersion medium, and the other is a dispersoid.
The production method according to claim 3, wherein the dispersion system is irradiated with light. The production method according to claim 4, wherein in the reaction step, the dispersoid is dispersed in the dispersion medium by stirring the reaction system. The production method according to claim 5, wherein the stirring method is at least one selected from the group consisting of a rotation treatment with a stirrer, a stirring treatment with a vortex mixer, and an ultrasonic treatment. In the reaction step, the reaction system is irradiated with light while being brought into contact with air.
The manufacturing method according to any one of claims 1 to 6. _{3. In the} reaction step, light is irradiated in a state where oxygen (O ₂ ) is dissolved in the aqueous phase.
7. The manufacturing method according to any one of 7. The production method according to any one of claims 1 to 8, wherein in the reaction step, the reaction is carried out in an atmosphere where the temperature is 0 to 100 ° C. and the pressure is 0.1 to 0.5 MPa. After the reaction step, the recovery step of recovering the diol is further included.
The production method according to any one of claims 3 to 9, wherein the recovery step is a step of recovering the aqueous phase containing the diol from the reaction system. Claims 1 to 1 wherein the organic phase contains an organic solvent and the organic solvent is a hydrocarbon solvent.
The production method according to any one of 0. Claims 1 to 1 in which the organic phase contains an organic solvent and the organic solvent is a halogenated solvent.
The production method according to any one of 0. Claims 1 to 1 in which the organic phase contains an organic solvent and the organic solvent is a fluorous solvent.
The production method according to any one of 0. The production method according to any one of claims 1 to 13, further comprising a chlorine dioxide radical generation step of generating the chlorine dioxide radical. The reaction system is a two-phase reaction system containing the organic phase and the aqueous phase.
Further, the chlorine dioxide radical generation step of generating the chlorine dioxide radical is included.
The invention according to any one of claims 1 to 14, wherein in the chlorine dioxide radical generation step, the aqueous phase contains the source of the chlorine dioxide radical and generates the chlorine dioxide radical from the source of the chlorine dioxide radical. Manufacturing method. In the chlorine dioxide radical generating step, the source of chlorine dioxide radicals chlorite ions (ClO 2 ^_-) a, wherein chlorine dioxide by the action of at least one Lewis acid and Bronsted acid to the chlorite ion The production method according to claim 15, wherein radicals are generated. The raw material is ethane or a derivative thereof.
The production method according to any one of claims 1 to 16, wherein the oxidation reaction product of the raw material is ethylene glycol. The raw material is propane or a derivative thereof.
The production method according to any one of claims 1 to 16, wherein the oxidation reaction product of the raw material is propylene glycol.