Production method for episulfide compound

Abstract

The present invention provides a production method for an episulfide compound that includes a step (A) for producing an episulfide compound that has at least two structures represented by formula (2) from an epoxy compound that has at least two structures represented by formula (1) and a step (B) for adding a mixed solvent of a protic polar solvent and an aprotic polar solvent to the reaction liquid from step (A). In formulas (1) and (2), R1 represents a C0–10 hydrocarbon group, R2, R3, and R4 each independently represent a C1–10 hydrocarbon group or a hydrogen atom, Y represents O, S, Se, or Te, and n represents 0 or 1.

Description

Method for producing episulfide compounds

[0001] The present invention relates to a method for producing an episulfide compound, and more particularly to a method for producing an episulfide compound that can suppress the generation of viscous by-products.

[0002] Plastic lenses are lightweight, highly tough, and easily dyeable. The specific properties required of plastic lenses include low specific gravity, high transparency, and low yellowness, as well as optical properties such as a high refractive index, a high Abbe number, high heat resistance, and high strength. A high refractive index enables lenses to be made thinner, and a high Abbe number reduces chromatic aberration in lenses. In recent years, development of compositions for optical materials containing compounds having episulfide groups has been progressing with the aim of achieving high refractive indexes and high Abbe numbers (Patent Documents 1 and 2). However, during the production of compounds having episulfide groups, an increase in the number of episulfide groups has led to the problem of viscous by-products precipitating and clogging piping. Pipe clogging makes mass production difficult.

[0003] WO2018 / 150951WO2020 / 031815

[0004] An object of the present invention is to provide a method for producing an episulfide compound that can suppress the generation of viscous by-products.

[0005] In view of these circumstances, the present inventors have conducted extensive research and found that the generation of viscous by-products can be suppressed by using a mixed solvent of a protic polar solvent and an aprotic polar solvent as a reaction terminator, and have thus arrived at the present invention. That is, the present invention is as follows: <1> A method for producing an episulfide compound, comprising: a step (A) of producing an episulfide compound having two or more structures represented by the following formula (2) from an epoxy compound having two or more structures represented by the following formula (1); and a step (B) of adding a mixed solvent of a protic polar solvent and an aprotic polar solvent to the reaction solution obtained after the step (A): (In the formula, R １ represents a hydrocarbon group having 0 to 10 carbon atoms, and R ２ , R ３ and R ４each independently represents a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom; Y represents O, S, Se, or Te; and n represents 0 or 1. (In the formula, R １ represents a hydrocarbon group having 0 to 10 carbon atoms, and R ２ , R ３ and R ４each independently represent a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom. Y represents O, S, Se, or Te, and n represents 0 or 1. <2> The method for producing an episulfide compound according to the above item <1>, wherein the protic polar solvent is at least one selected from the group consisting of water, an acidic aqueous solution, and an alcohol. <3> The method for producing an episulfide compound according to the above item <2>, wherein the acidic aqueous solution is at least one selected from the group consisting of a sulfuric acid aqueous solution, a hydrochloric acid aqueous solution, a nitric acid aqueous solution, a formic acid aqueous solution, a perchloric acid aqueous solution, a boric acid aqueous solution, a hydrofluoric acid aqueous solution, an acetic acid aqueous solution, a phosphoric acid aqueous solution, a hydroiodic acid aqueous solution, a hydrobromic acid aqueous solution, a phosphonic acid aqueous solution, a phosphinic acid aqueous solution, a diphosphoric acid aqueous solution, a metaphosphoric acid aqueous solution, a sulfurous acid aqueous solution, a chlorosulfonic acid aqueous solution, a carbonic acid aqueous solution, a propionic acid aqueous solution, and an oxalic acid aqueous solution. <4> The method for producing an episulfide compound according to the above item <2>, wherein the alcohol is at least one selected from the group consisting of allyl alcohol, 2-aminoethanol, benzyl alcohol, 1-butanol, 2-butanol, cyclohexanol, methanol, ethanol, 2-chloroethanol, 2-butoxyethanol, 2-ethoxyethanol, 2-ethylhexanol, furfuryl alcohol, 1-hexanol, 2-methoxyethanol, 2-methyl-2-butanol, isopentyl alcohol, 1-octanol, 2-octanol, 1-pentanol, 3-pentanol, phenol, and 1-propanol. <5> The method for producing an episulfide compound according to any one of the above items <1> to <4>, wherein the aprotic polar solvent is at least one selected from the group consisting of sulfoxides, nitriles, amides, ketones, esters, and ethers. <6> The method for producing an episulfide compound according to the above item <5>, wherein the sulfoxide is at least one selected from the group consisting of dimethyl sulfoxide, phenyl vinyl sulfoxide, 2-bromophenyl methyl sulfoxide, phenyl trifluoromethyl sulfoxide, and 1-isothiocyanato-4-(methylsulfinyl)butane.<7> The method for producing an episulfide compound according to the above item <5>, wherein the nitrile is at least one selected from the group consisting of acetonitrile, thiophene-3-acetonitrile, thiophene-2-acetonitrile, 3-(methylamino)propionitrile, (dimethylamino)acetonitrile, methoxyacetonitrile, phenylacetonitrile, methylaminoacetonitrile, diethylaminoacetonitrile, 2-phenylpropionitrile, and thiophene-2-acetonitrile. <8> The method for producing an episulfide compound according to the above item <5>, wherein the amide is at least one selected from the group consisting of dimethylformamide, dimethylacetamide, N-methylpropionamide, N,N-dimethylformamide dineopentyl acetal, N-methylmethacrylamide, N-(isobutoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N,N-diethyl-M-toluamide, N,O-bis(trimethylsilyl)acetamide, 2,2′-(methylimino)bis(N,N-di-N-octylacetamide), and N-vinylformamide. <9> The method for producing an episulfide compound according to the above item <5>, wherein the ketone is at least one selected from the group consisting of acetone, methyl ethyl ketone, methyl isobutyl ketone, diisopropyl ketone, butyl isopropyl ketone, SEC-butyl methyl ketone, isobutyl isopropyl ketone, isopropyl methyl ketone, phenyl 1-propenyl ketone, dicyclohexyl ketone, isobutyl phenyl ketone, methyl phenyl ketone, methyl vinyl ketone, 3-octanone, 3-nonanone, 3-methyl-1-phenyl-2-butanone, 5-methyl-2-hexanone, and 1-phenyl-2-butanone. <10> The method for producing an episulfide compound according to the above item <5>, wherein the ester is at least one selected from the group consisting of ethyl acetate, butyl acetate, n-propyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, octyl acetate, methyl butyrate, ethyl butyrate, pentyl butyrate, methyl salicylate, ethyl formate, ethyl propionate, ethyl caproate, and pentyl valerate.<11> The method for producing an episulfide compound according to the above <5>, wherein the ether is at least one selected from the group consisting of tetrahydrofuran, 1,4-dioxane, anisole, diethyl ether, ethyl methyl ether, N-propyl ether, dibutyl ether, diphenyl ether, diethylene glycol monobutyl ether, ethylene glycol, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene oxide, benzofuran, dibenzofuran, and crown ether. <12> The method for producing an episulfide compound according to any of the above <1> to <11>, wherein the step (A) is a step of producing an episulfide compound having two or more structures represented by formula (2) by reacting an epoxy compound having two or more structures represented by formula (1) with at least acetic anhydride and thiourea. <13> The method for producing an episulfide compound according to any one of the above items <1> to <12>, further comprising a step of reacting a compound having two or more mercapto groups with at least epichlorohydrin to produce an epoxy compound having two or more structures represented by formula (1).

[0006] According to the present invention, it is possible to provide a method for producing an episulfide compound that can suppress the generation of viscous by-products.

[0007] Hereinafter, the present invention will be described in detail by way of examples and working examples, but the present invention is not limited to the illustrated examples and working examples, and can be carried out by any method as long as it does not significantly deviate from the content of the present invention.

[0008] The present invention is a method for producing an episulfide compound, comprising: a step (A) of producing an episulfide compound having two or more structures represented by the following formula (2) from an epoxy compound having two or more structures represented by the following formula (1); and a step (B) of adding a mixed solvent of a protic polar solvent and an aprotic polar solvent to the reaction liquid after the step (A):

[0009] <Step (A)> In one embodiment of the present invention, an episulfide compound having two or more (preferably 2 to 10, more preferably 2 to 4) structures represented by the following formula (1) can be produced by reacting an epoxy compound having two or more (preferably 2 to 10, more preferably 2 to 4) structures represented by the following formula (2) with a thiating agent such as thiourea: (1) In the formula, R １ represents a hydrocarbon group having 0 to 10 carbon atoms, preferably a hydrocarbon group having 0 to 2 carbon atoms, and more preferably a methylene group. ２ , R ３ and R ４ each independently represents a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, preferably a hydrocarbon group having 1 to 2 carbon atoms or a hydrogen atom, more preferably a hydrogen atom. Y represents O, S, Se, or Te, preferably O or S, more preferably S. n represents 0 or 1, preferably 1. (2) In the formula, R １ ~R ４ , Y, and n have the same meanings as in formula (1).

[0010] In the present invention, the episulfide compound having two or more structures represented by the above formula (2) is not particularly limited, and specific examples include 1,3,5-tris(β-epithiopropyl)benzene, tetrakis(β-epithiopropylthiomethyl)methane, bis(β-epithiopropyl)sulfide, and 1,5-bis(2,3-epithiopropoxy)naphthalene.

[0011] In the method for obtaining an episulfide compound having two or more structures represented by the above formula (2) by the above reaction, the thiating agent such as thiourea is used in the number of moles corresponding to the epoxy of the epoxy compound having two or more structures represented by the above formula (1), i.e., in a theoretical amount. However, if priority is given to reaction rate and purity, the theoretical amount to 2.5 times the theoretical amount is used. Preferably, the amount is 1.3 times the theoretical amount to 2.0 times the theoretical amount, and more preferably, the amount is 1.5 times the theoretical amount to 2.0 times the theoretical amount. Examples of polar organic solvents in which thiourea can be dissolved include alcohols such as methanol and ethanol, ethers such as diethyl ether, tetrahydrofuran, and dioxane, and hydroxyethers such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve. However, alcohols are preferred, and methanol is most preferred.

[0012] Nonpolar organic solvents capable of dissolving epoxy compounds having two or more structures represented by formula (1) above include aliphatic hydrocarbons such as pentane, hexane, and heptane; aromatic hydrocarbons such as benzene and toluene; and halogenated hydrocarbons such as dichloromethane, chloroform, and chlorobenzene. Preferred are aromatic hydrocarbons, and toluene is most preferred. The solvent ratio is preferably polar organic solvent / nonpolar organic solvent = 0.1 to 10.0 by volume, more preferably polar organic solvent / nonpolar organic solvent = 0.2 to 5.0 by volume. A volume ratio of less than 0.1 results in insufficient dissolution of thiourea, preventing the reaction from proceeding sufficiently. A volume ratio exceeding 10.0 may result in significant polymer formation. The reaction temperature is preferably 10°C to 30°C. A temperature below 10°C may result in a slower reaction rate, as well as insufficient dissolution of thiourea, preventing the reaction from proceeding sufficiently. A temperature above 30°C may result in significant polymer formation.

[0013] It is preferable to add an acid or acid anhydride during the reaction. Preferred are acetic acid, propionic acid, butyric acid, succinic acid, maleic acid, benzoic acid, phthalic acid, pyromellitic acid, trimellitic acid, trifluoroacetic acid, and their acid anhydrides, and most preferred is acetic acid and its acid anhydride. The amount added is preferably in the range of 0.001% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass, based on the total amount of the reaction solution. If the amount added is less than 0.001% by mass, polymer formation will be significant and the reaction yield will decrease, while if it exceeds 10% by mass, the yield may decrease significantly.

[0014] In one embodiment of the present invention, it is particularly preferable that the step (A) is a step of producing an episulfide compound having two or more structures represented by the formula (2) by reacting an epoxy compound having two or more structures represented by the formula (1) with at least acetic anhydride and thiourea.

[0015] In one embodiment of the present invention, it is preferable to further include a step of producing an epoxy compound having two or more (preferably 2 to 10, more preferably 2 to 4) structures represented by formula (1) by reacting a compound having two or more (preferably 2 to 10, more preferably 2 to 4) mercapto groups with at least epichlorohydrin.

[0016] <Step (B)> In the present invention, step (B) is a step of adding a mixed solvent of a protic polar solvent and an aprotic polar solvent to the reaction solution after step (A). The method for adding the mixed solvent to the reaction solution after step (A) is not particularly limited, and any addition method commonly used in the art can be employed. Completion of step (A) can be confirmed, for example, by confirming that the reaction has stopped proceeding by HPLC analysis, but the method is not limited to this. Adding a mixed solvent of a protic polar solvent and an aprotic polar solvent to the reaction solution after step (A) can suppress the precipitation of viscous by-products. In particular, viscous by-products are likely to precipitate when producing episulfide compounds with two or more functionalities. Therefore, the present invention is particularly suitable for producing episulfide compounds with two or more functionalities. According to the present invention, the problem of precipitation of viscous by-products and clogging of piping due to the increase in episulfide groups in the raw material can be solved, which is preferable from the viewpoint of mass production.

[0017] In one embodiment of the present invention, the mass ratio of the protic polar solvent to the aprotic polar solvent in the mixed solvent used as the reaction terminator is preferably in the range of 1:10 to 10:1, and more preferably in the range of 1:1 to 1:4. Within such a range, the precipitation of viscous by-products can be effectively suppressed.

[0018] In one embodiment of the present invention, the mixed solvent used as the reaction terminator is preferably in a range of 1:1 to 1:60, more preferably 1:1 to 1:30, in terms of the mass ratio of the epoxy compound to the mixed solvent, relative to the epoxy compound having two or more structures represented by the formula (1). Within this range, the precipitation of viscous by-products can be effectively suppressed, and the yield is excellent.

[0019] In the present invention, the protic polar solvent used in step (B) is not particularly limited, but is preferably at least one selected from the group consisting of water, an acidic aqueous solution, and an alcohol. Among these, an acidic aqueous solution is more preferred. The acidic aqueous solution is not particularly limited, but is preferably at least one selected from the group consisting of an aqueous sulfuric acid solution, an aqueous hydrochloric acid solution, an aqueous nitric acid solution, an aqueous formic acid solution, an aqueous perchloric acid solution, an aqueous boric acid solution, an aqueous hydrofluoric acid solution, an aqueous acetic acid solution, an aqueous phosphoric acid solution, an aqueous hydroiodic acid solution, an aqueous hydrobromic acid solution, an aqueous phosphonic acid solution, an aqueous phosphinic acid solution, an aqueous diphosphoric acid solution, an aqueous metaphosphoric acid solution, an aqueous sulfurous acid solution, an aqueous chlorosulfonic acid solution, an aqueous carbonic acid solution, an aqueous propionic acid solution, and an aqueous oxalic acid solution. Among these, an aqueous sulfuric acid solution, an aqueous hydrochloric acid solution, and an aqueous formic acid solution are more preferred. The acid concentration in the acidic aqueous solution can be adjusted appropriately depending on the type of acid, but is preferably 0.1 to 30% by mass, more preferably 5 to 20% by mass.

[0020] The alcohol is not particularly limited, but is preferably at least one selected from the group consisting of allyl alcohol, 2-aminoethanol, benzyl alcohol, 1-butanol, 2-butanol, cyclohexanol, methanol, ethanol, 2-propanol, 2-chloroethanol, 2-butoxyethanol, 2-ethoxyethanol, 2-ethylhexanol, furfuryl alcohol, 1-hexanol, 2-methoxyethanol, 2-methyl-2-butanol, isopentyl alcohol, 1-octanol, 2-octanol, 1-pentanol, 3-pentanol, phenol, and 1-propanol. Of these, methanol, ethanol, and 2-propanol are more preferred.

[0021] In the present invention, the aprotic polar solvent used in step (B) is not particularly limited, but is preferably at least one selected from the group consisting of sulfoxides, nitriles, amides, ketones, esters, and ethers, with sulfoxides and amides being more preferred.

[0022] The sulfoxide is not particularly limited, but is preferably at least one selected from the group consisting of dimethyl sulfoxide, phenyl vinyl sulfoxide, 2-bromophenyl methyl sulfoxide, phenyl trifluoromethyl sulfoxide, and 1-isothiocyanato-4-(methylsulfinyl)butane, and among these, dimethyl sulfoxide and phenyl vinyl sulfoxide are more preferred.

[0023] The nitrile is not particularly limited, but is preferably at least one selected from the group consisting of acetonitrile, thiophene-3-acetonitrile, thiophene-2-acetonitrile, 3-(methylamino)propionitrile, (dimethylamino)acetonitrile, methoxyacetonitrile, phenylacetonitrile, methylaminoacetonitrile, diethylaminoacetonitrile, 2-phenylpropionitrile, and thiophene-2-acetonitrile. Among these, acetonitrile and methoxyacetonitrile are more preferred.

[0024] The amides are not particularly limited, but are preferably at least one selected from the group consisting of dimethylformamide, dimethylacetamide, N-methylpropionamide, N,N-dimethylformamide dineopentyl acetal, N-methylmethacrylamide, N-(isobutoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N,N-diethyl-M-toluamide, N,O-bis(trimethylsilyl)acetamide, 2,2'-(methylimino)bis(N,N-di-N-octylacetamide), and N-vinylformamide. Among these, dimethylformamide and dimethylacetamide are more preferred.

[0025] The ketone is not particularly limited, but is preferably at least one selected from the group consisting of acetone, methyl ethyl ketone, methyl isobutyl ketone, diisopropyl ketone, butyl isopropyl ketone, SEC-butyl methyl ketone, isobutyl isopropyl ketone, isopropyl methyl ketone, phenyl 1-propenyl ketone, dicyclohexyl ketone, isobutyl phenyl ketone, methyl phenyl ketone, methyl vinyl ketone, 3-octanone, 3-nonanone, 3-methyl-1-phenyl-2-butanone, 5-methyl-2-hexanone, and 1-phenyl-2-butanone. Among these, acetone and methyl ethyl ketone are more preferred.

[0026] The ester is not particularly limited, but is preferably at least one selected from the group consisting of ethyl acetate, butyl acetate, n-propyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, octyl acetate, methyl butyrate, ethyl butyrate, pentyl butyrate, methyl salicylate, ethyl formate, ethyl propionate, ethyl caproate, and pentyl valerate. Among these, ethyl acetate and butyl acetate are more preferred.

[0027] The ether is not particularly limited, but is preferably at least one selected from the group consisting of tetrahydrofuran, 1,4-dioxane, anisole, diethyl ether, ethyl methyl ether, N-propyl ether, dibutyl ether, diphenyl ether, diethylene glycol monobutyl ether, ethylene glycol, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene oxide, benzofuran, dibenzofuran, and crown ethers. Among these, tetrahydrofuran and diethyl ether are more preferred.

[0028] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Viscous by-products and yield were evaluated according to the following criteria.

[0029] <Viscous by-products> A: Not visible. B: Slight precipitation. C: Precipitation occurs, clogging the funnel. -: Not evaluated because the yield of the target product was 0%.

[0030] <Yield> A: 50% or more B: Less than 50% C: The target product is not obtained.

[0031] Example 1 (1) Synthesis of Episulfide Compound Material A 2 L three-neck flask was equipped with a thermocouple, an inlet tube, and a dropping funnel. After the atmosphere in the vessel was replaced with nitrogen, 70.00 g of trimercaptobenzene and 303.38 g of toluene were added and stirred at 5°C. A mixed solution of 3.34 g of 24% aqueous sodium hydroxide and 110.85 g of methanol was then added, and the temperature in the vessel was maintained at 5°C. Next, 115.19 g of epichlorohydrin was added dropwise, and the reaction was continued for 3 hours. Subsequently, 334.69 g of 24% aqueous sodium hydroxide was added using the dropping funnel while maintaining the temperature in the vessel at 15°C. After the dropwise addition, the liquid temperature was set to 15°C, and stirring was continued for 24 hours. 24 hours after the addition of the aqueous sodium hydroxide, 167.96 g of methanol was added to the reaction solution, and stirring was continued until HPLC analysis revealed an intermediate area percentage of ≦1.0%. Thereafter, 700.0 g of water was added to terminate the reaction. The reaction solution was transferred to a separatory funnel, and the organic layer was washed three times with 700.0 g of water, after which the organic layer was recovered. The organic layer was concentrated using an evaporator and dried under vacuum to obtain an epoxy compound represented by the following formula (3) (hereinafter, sometimes referred to as "compound 3").

[0032] (2) Synthesis of 1,3,5-tris(β-epithiopropyl)benzene 20.00 g of the epoxy compound represented by formula (3) above was added to a 2-L recovery flask and a blowing tube was attached. Then, 86.68 g of toluene, 79.18 g of methanol, and 1.07 g of acetic anhydride were added, and the liquid temperature was set to 20°C and stirred in an open system. 20.00 g of thiourea was then added, and the mixture was stirred at 20°C for 26 hours. After confirming that the reaction had stopped proceeding by HPLC analysis, 600.00 g of a mixed solvent (200.00 g of 20% sulfuric acid as a protic polar solvent and 400.00 g of dimethyl sulfoxide (DMSO) as an aprotic polar solvent (20% sulfuric acid:DMSO = 1:2) was added to the reaction solution as a reaction terminator (compound 3:mixed solvent = 1:30) to quench the reaction. The liquid temperature was set to 20°C, and the mixture was stirred for 1 hour. After stirring, the solution was transferred to a separatory funnel. No viscous by-products were observed in the recovery flask. The separatory funnel was allowed to stand, and after the layers separated, the lower layer was discarded and the organic layer was recovered. 200.00 g of 20% sulfuric acid was added to the organic layer, and the aqueous layer was removed. The organic layer was then washed three times with 200.00 g of water using the same procedure. The recovered organic layer was concentrated and vacuum dried at 40°C. 1,3,5-tris(β-epithiopropyl)benzene, an episulfide compound represented by the following formula (4), was obtained as a yellow liquid in a yield of 50-60%, with an HPLC purity (area %) of >98% and an HPLC purity (gravimetric analysis) of >97%. After the reaction, only a white solid precipitated in the reactor, and no viscous by-products were observed. Furthermore, the reactor could be easily washed with THF.

[0033] Example 2 An episulfide compound was produced in the same manner as in Example 1, except that the mass ratio of the components in the mixed solvent (20% sulfuric acid:DMSO) serving as the reaction terminator was changed from 1:2 to 10:1. The generation of viscous by-products in the flask after the reaction is shown in Table 1.

[0034] Example 3 An episulfide compound was produced in the same manner as in Example 1, except that the mass ratio of the components in the mixed solvent (20% sulfuric acid:DMSO) serving as the reaction terminator was changed from 1:2 to 1:10. The state of generation of viscous by-products in the flask after the reaction is shown in Table 1.

[0035] Example 4 An episulfide compound was produced in the same manner as in Example 1, except that the ratio of compound 3 to the mixed solvent added was changed from 1:30 to 1:1. The state of viscous by-products generated in the flask after the reaction is shown in Table 1.

[0036] (Example 5) An episulfide compound was produced in the same manner as in Example 1, except that the ratio of compound 3 to the mixed solvent added was changed from 1:30 to 1:60 in Example 1. The state of viscous by-products generated in the flask after the reaction is shown in Table 1.

[0037] (Example 6) An episulfide compound was produced in the same manner as in Example 1, except that 5% sulfuric acid was used as the protic polar solvent instead of 20% sulfuric acid in Example 1. The state of generation of viscous by-products in the flask after the reaction is shown in Table 1.

[0038] (Example 7) An episulfide compound was produced in the same manner as in Example 1, except that 30% sulfuric acid was used as the protic polar solvent instead of 20% sulfuric acid in Example 1. The state of generation of viscous by-products in the flask after the reaction is shown in Table 1.

[0039] (Example 8) An episulfide compound was produced in the same manner as in Example 1, except that N,N-dimethylformamide (DMF) was used instead of DMSO as the aprotic polar solvent in Example 1. The generation of viscous by-products in the flask after the reaction is shown in Table 1.

[0040] Example 9: Instead of the epoxy compound represented by formula (3) above, a tetrafunctional epoxy compound derived from tetramercaptopentaerythritol represented by formula (5) below was added to a 2-L recovery flask, and a blowing tube was attached. Then, 86.68 g of toluene, 79.18 g of methanol, and 1.15 g of acetic anhydride were added, and the liquid temperature was set to 20°C and stirred in an open system. Then, 21.51 g of thiourea was added, and the mixture was stirred at 20°C for 24 hours. After confirming that the reaction had stopped proceeding by HPLC analysis, 600.00 g of a mixed solvent (200.00 g of 20% sulfuric acid as a protic polar solvent and 400.00 g of DMSO as an aprotic polar solvent) (20% sulfuric acid:DMSO = 1:2) was added to the reaction solution as a reaction terminator (compound 3:mixed solvent = 1:30) to quench the reaction. The liquid temperature was set to 20°C, and the mixture was stirred for 1 hour. After stirring, the solution was transferred to a separatory funnel. No viscous by-products were observed in the recovery flask used as the reaction vessel. The separatory funnel was allowed to stand, and after the layers separated, the lower layer was discarded and the organic layer was recovered. 200.00 g of 20% sulfuric acid was added to the organic layer, and after acid washing, the aqueous layer was removed. The organic layer was then washed three times with 200.00 g of water using the same procedure. The recovered organic layer was concentrated and vacuum dried at 40°C, yielding tetrakis(β-epithiopropylthiomethyl)methane, a yellow liquid episulfide compound represented by formula (6) below, in a yield of 50-60%, with an HPLC purity (area %) of >95% and an HPLC purity (gravimetric analysis) of >96%. After the reaction, only a white solid precipitated in the vessel, and no viscous by-products were observed. Furthermore, the vessel could be easily washed with THF after the reaction.

[0041] Comparative Example 1 An episulfide compound was produced in the same manner as in Example 1, except that no aprotic polar solvent was added to the reaction terminator in Example 1. The state of generation of viscous by-products in the flask after the reaction is shown in Table 1.

[0042] Comparative Example 2 An episulfide compound was produced in the same manner as in Example 1, except that a protic polar solvent was not added to the reaction terminator. The state of viscous by-products generated in the flask after the reaction is shown in Table 1.

[0043] (Comparative Example 3) An episulfide compound was produced in the same manner as in Example 1, except that toluene, a nonpolar solvent, was used instead of DMSO, an aprotic polar solvent. The state of generation of viscous by-products in the flask after the reaction is shown in Table 1.

[0044] The results of evaluation of the evaluation items for Examples 1 to 9 and Comparative Examples 1 to 3 are shown in Table 1.

Claims

1. A step (A) of producing an episulfide compound having two or more structures represented by the following formula (2) from an epoxy compound having two or more structures represented by the following formula (1); and step (B) of adding a mixed solvent of a protic polar solvent and an aprotic polar solvent to the reaction solution after step (A). 【Chemistry 1】 (In the formula, R １ represents a hydrocarbon group having 0 to 10 carbon atoms, and R ２ , R ３ and R ４ each independently represents a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom; Y represents O, S, Se, or Te; and n represents 0 or 1. 【Chemistry 2】 (In the formula, R １ represents a hydrocarbon group having 0 to 10 carbon atoms, and R ２ , R ３ and R ４ each independently represents a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom; Y represents O, S, Se, or Te; and n represents 0 or 1.

2. 2. The method for producing an episulfide compound according to claim 1, wherein the protic polar solvent is at least one selected from the group consisting of water, an acidic aqueous solution, and an alcohol.

3. 3. The method for producing an episulfide compound according to claim 2, wherein the acidic aqueous solution is at least one selected from the group consisting of an aqueous sulfuric acid solution, an aqueous hydrochloric acid solution, an aqueous nitric acid solution, a formic acid solution, a perchloric acid solution, a boric acid solution, an aqueous hydrofluoric acid solution, an aqueous acetic acid solution, a phosphoric acid solution, an aqueous hydroiodic acid solution, an aqueous hydrobromic acid solution, an aqueous phosphonic acid solution, an aqueous phosphinic acid solution, an aqueous diphosphoric acid solution, an aqueous metaphosphoric acid solution, an aqueous sulfurous acid solution, an aqueous chlorosulfonic acid solution, an aqueous carbonic acid solution, an aqueous propionic acid solution, and an aqueous oxalic acid solution.

4. The method for producing an episulfide compound according to claim 2, wherein the alcohol is at least one selected from the group consisting of allyl alcohol, 2-aminoethanol, benzyl alcohol, 1-butanol, 2-butanol, cyclohexanol, methanol, ethanol, 2-chloroethanol, 2-butoxyethanol, 2-ethoxyethanol, 2-ethylhexanol, furfuryl alcohol, 1-hexanol, 2-methoxyethanol, 2-methyl-2-butanol, isopentyl alcohol, 1-octanol, 2-octanol, 1-pentanol, 3-pentanol, phenol, and 1-propanol.

5. 5. The method for producing an episulfide compound according to claim 1, wherein the aprotic polar solvent is at least one selected from the group consisting of sulfoxides, nitriles, amides, ketones, esters, and ethers.

6. The method for producing an episulfide compound according to claim 5, wherein the sulfoxide is at least one selected from the group consisting of dimethyl sulfoxide, phenyl vinyl sulfoxide, 2-bromophenyl methyl sulfoxide, phenyl trifluoromethyl sulfoxide, and 1-isothiocyanato-4-(methylsulfinyl)butane.

7. The method for producing an episulfide compound according to claim 5, wherein the nitrile is at least one selected from the group consisting of acetonitrile, thiophene-3-acetonitrile, thiophene-2-acetonitrile, 3-(methylamino)propionitrile, (dimethylamino)acetonitrile, methoxyacetonitrile, phenylacetonitrile, methylaminoacetonitrile, diethylaminoacetonitrile, 2-phenylpropionitrile, and thiophene-2-acetonitrile.

8. The method for producing an episulfide compound according to claim 5, wherein the amide is at least one selected from the group consisting of dimethylformamide, dimethylacetamide, N-methylpropionamide, N,N-dimethylformamide dineopentyl acetal, N-methylmethacrylamide, N-(isobutoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N,N-diethyl-M-toluamide, N,O-bis(trimethylsilyl)acetamide, 2,2'-(methylimino)bis(N,N-di-N-octylacetamide), and N-vinylformamide.

9. The method for producing an episulfide compound according to claim 5, wherein the ketone is at least one selected from the group consisting of acetone, methyl ethyl ketone, methyl isobutyl ketone, diisopropyl ketone, butyl isopropyl ketone, SEC-butyl methyl ketone, isobutyl isopropyl ketone, isopropyl methyl ketone, phenyl 1-propenyl ketone, dicyclohexyl ketone, isobutyl phenyl ketone, methyl phenyl ketone, methyl vinyl ketone, 3-octanone, 3-nonanone, 3-methyl-1-phenyl-2-butanone, 5-methyl-2-hexanone, and 1-phenyl-2-butanone.

10. 6. The method for producing an episulfide compound according to claim 5, wherein the ester is at least one selected from the group consisting of ethyl acetate, butyl acetate, n-propyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, octyl acetate, methyl butyrate, ethyl butyrate, pentyl butyrate, methyl salicylate, ethyl formate, ethyl propionate, ethyl caproate, and pentyl valerate.

11. The method for producing an episulfide compound according to claim 5, wherein the ether is at least one selected from the group consisting of tetrahydrofuran, 1,4-dioxane, anisole, diethyl ether, ethyl methyl ether, N-propyl ether, dibutyl ether, diphenyl ether, diethylene glycol monobutyl ether, ethylene glycol, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene oxide, benzofuran, dibenzofuran, and crown ethers.

12. 5. The method for producing an episulfide compound according to any one of claims 1 to 4, wherein the step (A) is a step of producing an episulfide compound having two or more structures represented by the formula (2) by reacting an epoxy compound having two or more structures represented by the formula (1) with at least acetic anhydride and thiourea.

13. 5. The method for producing an episulfide compound according to claim 1, further comprising a step of reacting a compound having two or more mercapto groups with at least epichlorohydrin to produce an epoxy compound having two or more structures represented by formula (1).

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