JP2011121898A - Method of producing pyridyl ethanethiol compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a pyridyl ethanethiol compound at a high yield, and to improve the operation efficiency and productivity by preventing problems such as the generation of a deposit sticking to the production equipment and the plugging of pipelines, in producing the same by the reaction of vinylpyridine and a sulfur-containing compound. <P>SOLUTION: There is disclosed a method of producing a pyridyl ethanethiol compound from vinylpyridine and a sulfur-containing compound as raw materials, which method is characterized in that the vinylpyridine contains a polymer in an amount of not higher than 2 wt.%. By using vinyl pyridine of a low polymer content, a greater amount of a pyridyl ethanethiol compound per the charged raw materials is produced, a pyridyl ethanethiol compound is produced at a high yield, the precipitation and the generation of a solid component in the production equipment are prevented, and problems such as the disruption of the liquid flow and the plugging of pipelines caused by the solid component sticking to the inner wall of the production equipment or staying in the corners or in the narrow parts thereof are prevented. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a pyridylethanethiol compound. Specifically, it is a compound useful as a synthetic intermediate for pharmaceuticals, agricultural chemicals, etc., and in particular, a sulfonic acid group of a sulfonic acid type cation exchange resin used as an acidic catalyst when a bisphenol compound is produced from a phenol compound and a carbonyl compound. The present invention relates to a method for industrially advantageously producing a pyridylethanethiol compound that is also useful as a modifying agent.

  Conventionally, many proposals have been made as methods for producing pyridylethanethiol compounds. For example, 4-vinylpyridine is reacted with thiourea, which is a sulfur-containing compound, in the presence of paratoluenesulfonic acid in an ethanol solvent. There is known a method of producing an isothioronium salt and then converting it to 2- (4-pyridyl) ethanethiol in ammonia water (see, for example, Non-Patent Document 1). (For example, see Patent Documents 1 and 2).

  A method for producing 2- (4-pyridyl) ethanethiol easily without isolating the isothioronium salt by performing an isothiolonium salt generation reaction in an aqueous solvent and then reacting the solution with an aqueous ammonia solution. Has also been proposed (see, for example, Patent Document 3).

  In addition to the above, a method of using thioacetic acid as a sulfur-containing compound and reacting vinylpyridine and thioacetic acid to obtain pyridylethylthioacetate as a pyridylethylthio compound (see, for example, Patent Documents 5 and 6), A method is also known in which hydrogen sulfide is used as a sulfur compound and vinylpyridine and hydrogen sulfide are reacted to obtain pyridylethanethiol as a pyridylethylthio compound (for example, Patent Document 7). The above pyridylethylthioacetate can be easily converted to pyridylethanethiol by decomposition in the presence of an acid, but bisphenol can be obtained by condensation of phenol and acetone while the mercapto group remains a derivative protected with an acetyl group. It can also be used as a catalyst modifier in the production of A.

  As a general production method of vinylpyridine which is one of starting materials for producing a pyridylethanethiol compound, 2- (4-pyridyl) ethanol or 2- (2-pyridyl) ethanol is obtained by methylolation reaction of picoline and formaldehyde. A method is known in which 2-pyridylethanol is produced and subjected to a dehydration reaction in the presence of an alkali (see, for example, Patent Document 4). The vinyl pyridine produced here is purified by distillation, for example, but the product contains several types of impurities. These impurities are unreacted raw material picoline, by-products ethyl pyridine, isopropenyl pyridine, propenyl pyridine, methyl vinyl pyridines having a pyridine skeleton with a methyl group and a vinyl group, and a dimer of pinyl pyridine. These homopolymers and the like.

JP-A-11-228540 JP-A-11-255748 JP 2002-220373 A Japanese Patent Laid-Open No. 53-1444577 US Pat. No. 6,534,686 US Pat. No. 6,620,939 US Pat. No. 6,667,402

Journal of Organic Chemistry (J. Org. Chem.) 26, 82 (1961)

  However, when a pyridylethanethiol compound is produced using vinylpyridines and a sulfur-containing compound as raw materials according to the above method, there is a problem that the yield of the pyridylethanethiol compound is unexpectedly low.

  In addition, in the conventional method, there is a problem of equipment contamination due to continued operation in the production facility for pyridylethanethiol compound (generation of sticking matter on the inner wall of the equipment). There is a problem that maintenance frequency is high, equipment operation efficiency and production efficiency are poor, such as cleaning operation to stop operation and remove solid content adhered in the equipment. .

  Conventionally, regarding vinylpyridines, which are raw materials for producing pyridylethanethiol compounds, pretreatments such as simple distillation for the purpose of removing colored substances and impurities have been studied. No examination has been made from the viewpoint of improvement of the rate, generation of sticking matter in the production facility, and prevention of adhesion, and such a problem has not been solved.

  The present invention has been made in view of the above-described conventional situation, and in a method for producing a pyridylethanethiol compound using vinylpyridines and a sulfur-containing compound as raw materials, the pyridylethanethiol compound is produced in a high yield. At the same time, it is an object of the present invention to prevent problems such as the generation of sticking matters in production equipment and blockage of piping, and to improve operation efficiency and production efficiency.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that vinylpyridines, which are raw materials for producing pyridylethanethiol compounds, include dimer or higher vinylpyridines during synthesis and during storage after synthesis. This polymer is produced and contaminated as an impurity, and this polymer decreases the yield of the pyridylethanethiol compound, causes sticking in the production facility, and the polymer in the raw vinyl pyridines. The inventors have found that the above problem can be solved by regulating the amount, and have completed the present invention.

  That is, the method for producing a pyridylethanethiol compound according to the present invention (Claim 1) is a method for producing a pyridylethanethiol compound using a vinylpyridine and a sulfur-containing compound as raw materials, The polymer contained in the pyridines is 2% by weight or less.

  The method for producing a pyridylethanethiol compound according to claim 2 is characterized in that, in claim 1, the polymer contained in the vinylpyridines is 100 ppm by weight or more.

  The method for producing a pyridylethanethiol compound according to claim 3 is the method according to claim 1 or 2, wherein the vinylpyridine is 2-vinylpyridine, the sulfur-containing compound is thiourea, and the pyridylethanethiol compound is 2- It is (2-pyridyl) ethanethiol.

  According to the present invention, the amount of the pyridylethanethiol compound per raw material is increased by using a vinylpyridine of 2 wt% or less of the polymer contained in the vinylpyridines as the raw material for producing the pyridylethanethiol compound, A pyridylethanethiol compound can be obtained in high yield.

Moreover, the precipitation and generation of solids in the production facility for pyridylethanethiol compounds is prevented, and this solid matter adheres to the inner wall of the device or stays in the corners or narrow parts, resulting in liquid feeding obstacles and piping. Occlusion problems are also prevented.
For this reason, the frequency of maintenance such as stopping the operation and washing and removing the fixed matter inside the apparatus is reduced, the operating efficiency of the apparatus is improved, the maintenance frequency is reduced, and the operating efficiency is improved. The manufacturing cost can be reduced and the production efficiency can be improved.

  Hereinafter, embodiments of the production method of the pyridylethanethiol compound and the acidic catalyst of the present invention will be described in detail. However, the description of the constituent elements described below is an example of the embodiment of the present invention, and the present invention is Unless it exceeds the gist, it is not specified in these contents.

  First, in the present invention, vinylpyridines used as a raw material for producing a pyridylethanethiol compound will be described.

  The vinylpyridines used in the present invention are represented by the following general formula (I).

(I) In the formula, n is an integer of 1 to 5, and at least one selected from the group consisting of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ is a —CH═CH ₂ group, R ₁ , R ₂ , R ₃ , R ₄ and R _{5 which} are not —CH═CH ₂ groups are each independently a hydrogen atom, a fluorine atom, a bromine atom, a chlorine atom, an iodine atom, a vinyl group, a hydroxyl group, or a carbon atom number. Via an alkoxy functional group of 1 to 10, an aryloxy functional group having 6 or more carbon atoms, an aliphatic functional group having 1 to 10 carbon atoms, an aromatic functional group having 6 or more carbon atoms, or an adjacent ring substituent It is one selected from the group consisting of an alicyclic ring having 5 or more carbon atoms condensed with a pyridine ring and an aromatic ring having 6 or more carbon atoms condensed with a pyridine ring via an adjacent ring substituent. .

  These vinylpyridines are appropriately selected and used in accordance with the structure of the target pyridylethanethiol compound. For example, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-4-vinylpyridine, 4 -Substituted vinyl pyridines such as methyl-2-vinyl pyridine, 2,4-divinyl pyridine, 2,6-divinyl pyridine, 3,5-divinyl pyridine, and the like can be mentioned, but not limited thereto. Further, these vinyl pyridines are ethyl pyridine, 2-isopropenyl pyridine, 4-isopropenyl pyridine within a range that does not hinder the effects of the present invention and does not hinder the use of the resulting pyridine ethanethiol compound. , 2- (2-pyridyl) ethanol, 2- (4-pyridyl) ethanol and the like may be contained.

  In particular, in the present invention, the vinylpyridine is 2-vinylpyridine for the following reasons, and is effective when 2- (2-pyridyl) ethanethiol is produced from this 2-vinylpyridine.

  That is, 2-vinylpyridine is easily polymerized during the synthesis of 2-vinylpyridine and during subsequent storage from the vinyl group and the position of the nitrogen atom of the pyridine ring, and the polymer tends to increase. However, even if it is 2-vinylpyridine which such a polymer tends to produce | generate, the effect by this invention is exhibited effectively by making the polymer contained in vinylpyridines into 2 weight% or less.

  The polymer contained in the vinyl pyridines in the present invention is a dimer or more produced by polymerization of vinyl pyridines or polymerizable impurities during synthesis or during storage of the product vinyl pyridines thereafter. It is a polymer.

  When the amount of the polymer contained in the vinylpyridines used as a raw material for the pyridylethanethiol compound is more than 2% by weight, when the pyridylethanethiol compound is produced, the production amount per charged raw material is reduced and The production amount of water is large, and the production efficiency is greatly reduced, such as troubles in the blockage of piping and the need for cleaning to remove the solid matter adhering to the inside of the apparatus. If the polymer content in the vinyl pyridines is 2% by weight or less, the pyridylethanethiol compound can be obtained in a high yield, and since the amount of precipitated solids is small, it is difficult to block the piping. Since it is possible to reduce the frequency of washing or to eliminate the washing for removing the solid content adhering to the inside, high production efficiency can be maintained.

  The smaller the polymer contained in the vinyl pyridines, the more preferable, 1.0% by weight or less is more preferable, and 0.5% by weight or less is still more preferable. However, in order to obtain an extremely low concentration, it is necessary to carry out a purification operation described later at a high level, and it is necessary to perform distillation purification again immediately before use, so that costs for purification and distillation are excessively high. Or, in order to suppress the formation of polymer during storage, it is necessary to store at a very low temperature using a large amount of polymerization inhibitor, and the cost at the time of storage and transportation increases, and it is difficult to obtain an effect commensurate with the cost. Therefore, the lower limit of the contained polymer is preferably 100 ppm by weight.

As a method for quantifying polymers in vinylpyridines, among these polymers, those having a low molecular weight such as dimers and trimers are NMR (nuclear magnetic resonance), GC (gas chromatography), LC (liquid chromatography). Quantification etc. directly.
On the other hand, as a method for quantifying a high molecular weight polymer, specifically a polymer having a tetramer or higher, a GPC (gel permeation chromatography) is used to detect a UV (ultraviolet) detector or a RI (differential refractive index) detector. Quantification by calculating based on the peaks detected in, and by separating the polymer by reprecipitation using the difference in solubility between the monomer and polymer in the organic solvent, and weighing the separated and recovered polymer The method of doing is mentioned.

  The molecular weight of the high molecular weight polymer mentioned here can be calculated using a standard polystyrene sample based on the peak measured by GPC.

  When these polymers are contained in vinylpyridines, they directly affect the purity of the vinylpyridines and cause a reduction in the yield of the pyridylethanethiol compound. Among these polymers, particularly those having a molecular weight of 2000 or more. Since the high molecular weight polymer is directly or further polymerized in the production system of the pyridylethanethiol compound, it becomes a factor that generates a solid component that does not dissolve in the reaction solvent by reacting with other substances. Among these polymers, it is preferable that the content of a high molecular weight polymer having a molecular weight of 2000 or more is 1.0% by weight or less, particularly 0.5% by weight or less, among polymers of vinylpyridine dimer or higher.

  Thus, for example, the polymer content determined by the GPC method shown in the Examples section below is 1.0% by weight or less, particularly 0.5% by weight or less, and the polymer content determined by the reprecipitation method. It is preferable to use vinyl pyridines having an amount of 1.0% by weight or less, particularly 0.5% by weight or less. The lower limit of these high molecular weight polymers is also preferably 100 ppm by weight for the same reason as the polymer.

The method for making the polymer contained in the vinylpyridines 2% by weight or less is not particularly limited, but usually a purification means by distillation is employed. For example, vinylpyridines are purified using a vacuum distillation facility. Specifically, the number of stages is usually 1 or more, preferably 2 to 10 equivalent distillation towers, preferably packed towers, and the conditions such as pressure are adjusted so that the top temperature is 30 to 150 ° C. And then distill.
In addition, the purified vinylpyridines are added with a polymerization inhibitor such as tert-butylpyrocatechol or hydroquinone in an amount of about 100 to 1000 ppm by weight in order to prevent formation of a polymer during storage, and have a low temperature of about −5 ° C. or lower. For example, it is preferable to store at -5 ° C to -40 ° C.

  The kind of the sulfur-containing compound used in the present invention is not particularly limited as long as it produces a pyridylethanethiol compound as a result of the reaction with vinylpyridines. Specific examples of the sulfur-containing compound include thiourea, thioacetic acid, hydrogen sulfide, sodium sulfide, etc., preferably thiourea or thioacetic acid. Among them, ease of handling and reaction yield From this point, thiourea is particularly preferable.

The production of the pyridylethanethiol compound according to the present invention can be performed according to a conventional method using vinylpyridines and a sulfur-containing compound having a reduced polymer content as described above.
For example, a method for obtaining an isothioronium salt using thiourea as a sulfur-containing compound and hydrolyzing the obtained isothioronium salt, a method for obtaining pyridylethylthioacetate using thioacetic acid as a sulfur-containing compound, and a method for obtaining a sulfur-containing compound Examples thereof include a method for obtaining pyridylethanethiol using hydrogen sulfide.

Hereinafter, an example using thiourea as the sulfur-containing compound will be described as a representative example.
First, vinylpyridines and thiourea are reacted in the presence of an acid to obtain an isothioronium salt represented by the following general formula (II).

(II) In the formula, n is an integer of 1 to 5, and at least one selected from the group consisting of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ is (—C ₂ H ₄ —S— _{C (NH 2) (NH 2} ) +) is a _{chain, (- C 2 H 4 -S} -C (NH 2) (NH 2) +) non-chain _{R 1, R 2, R 3} , R 4 and R ₅ are each independently hydrogen atom, fluorine atom, bromine atom, chlorine atom, iodine atom, vinyl group, hydroxyl group, alkoxy functional group having 1 to 10 carbon atoms, aryloxy functional group having 6 or more carbon atoms, carbon An aliphatic functional group having 1 to 10 atoms, an aromatic functional group having 6 or more carbon atoms, an alicyclic ring having 5 or more carbon atoms fused with a pyridine ring via an adjacent ring substituent, and an adjacent ring Selected from the group consisting of aromatic rings having 6 or more carbon atoms fused with a pyridine ring via a substituent It is one that is.
X ^- is a residue of acid used.

  Here, as the acid, organic acids such as paratoluenesulfonic acid, benzenesulfonic acid and trifluoromethanesulfonic acid, and general inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid are used. Of these, aromatic sulfonic acids such as paratoluenesulfonic acid and benzenesulfonic acid, and sulfuric acid are preferable from the viewpoint of easy handling, and paratoluenesulfonic acid or sulfuric acid is particularly preferable.

The acid is used in a stoichiometric amount or more with respect to the vinylpyridines, but when used in a large excess, there is a possibility of causing a side reaction. Hereinafter, it is preferably used so as to be 3 equivalents or less.
Further, thiourea is used in a stoichiometric amount or slightly in excess of vinylpyridines, but is usually 1.5 equivalents or less, preferably 1.3 equivalents or less based on vinylpyridines.

  The reaction is performed by adding an acid and thiourea in an organic solvent such as alcohol or an aqueous solvent and then dissolving them, and then dropping vinylpyridines with stirring, and preferably in an inert gas atmosphere such as nitrogen. The acid concentration in the reaction solution is preferably as high as possible without impairing the ease of reaction operation. In the case of sulfuric acid, it is usually 5 to 50% by weight, preferably 20 to 40% by weight. Moreover, reaction temperature is 30-100 degreeC normally, Preferably it is 50-100 degreeC, and reaction time is 1 to 10 hours normally.

  Next, after the formation reaction of the isothioronium salt is completed, the obtained isothioronium salt is subjected to alkaline hydrolysis to obtain a pyridylethanethiol compound represented by the following general formula (III).

(III) In the formula, n is an integer of 1 to 5, and at least one selected from the group consisting of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ is (—C ₂ H ₄ —SH). R ₁ , R ₂ , R ₃ , R ₄ and R _{5 which} are chains and are not (—C ₂ H ₄ —SH) chains are each independently hydrogen atom, fluorine atom, bromine atom, chlorine atom, iodine atom, vinyl Group, hydroxyl group, alkoxy functional group having 1 to 10 carbon atoms, aryloxy functional group having 6 or more carbon atoms, aliphatic functional group having 1 to 10 carbon atoms, aromatic functional group having 6 or more carbon atoms, A group consisting of an alicyclic ring having 5 or more carbon atoms fused with a pyridine ring via an adjacent ring substituent, and an aromatic ring having 6 or more carbon atoms fused with a pyridine ring via an adjacent ring substituent It is 1 type selected from.

In the above general formula (III), the substitution position of the —C ₂ H ₄ —SH group to the pyridine ring is not particularly limited, and is in the 2nd position (ortho position), 3rd position (meta position), 4th position (para position). As described above, in the method for producing a pyridylethanethiol compound of the present invention, as described above, the production of 2- (2-pyridyl) ethanethiol in which the —C ₂ H ₄ —SH group is substituted at the 2-position of the pyridine ring. Is preferred.

  Specifically, the hydrolysis reaction of the isothioronium salt is carried out by adding alkali to the reaction liquid for producing the above isothioronium salt to make the liquid property alkaline. A metal hydroxide such as sodium hydroxide can be used as the alkali, but ammonia is preferably used. When ammonia is used, the decomposition reaction proceeds as follows.

(In the above reaction formula, X ⁻ has the same meaning as in general formula (II).)

  The required amount of ammonia is two times the stoichiometric amount with respect to the isothioronium salt, but is usually used in excess to allow the reaction to proceed sufficiently. Specifically, the amount of ammonia used is usually 3 to 15 times the mol of vinylpyridines used as a raw material in addition to the amount required to neutralize the acid in the previous step present in the isothioronium salt solution. Preferably it is 3-5 times mole. When the amount of ammonia used is too large, the yield generally decreases. This is presumed to be because the produced pyridylethanethiol compound causes a side reaction. Ammonia is usually used as ammonia water that is easy to handle, but its concentration may be determined appropriately in consideration of operability in subsequent filtration and extraction steps. Usually, about 5 to 28% by weight of ammonia water is used.

  In addition, in this hydrolysis reaction, if necessary, an organic solvent serving as an extraction solvent to be described later may be added to the isothioronium salt production reaction solution in an amount of 0.1 to 1 times the aqueous phase and diluted. This is advantageous because it can further reduce the amount of polymer produced.

  The hydrolysis reaction from the isothioronium salt to the pyridylethanethiol compound is completed in 0.5 to 10 hours at 30 to 70 ° C. with stirring. This hydrolysis reaction proceeds even at room temperature, but the reaction rate is slow. On the other hand, when the reaction is carried out at a high temperature, a side reaction occurs and the yield tends to decrease.

  After completion of the reaction, when aromatic sulfonic acid is used as the acid, the reaction product solution is cooled to about 10 ° C. to precipitate a by-produced guanidinium salt, and further filtered with an extraction solvent such as toluene, insoluble. Remove objects. The filter cake is further washed with an extraction solvent, and the washing solution is combined with the filtrate. The filtrate is then separated and the extraction solvent phase is recovered.

  On the other hand, when an inorganic acid such as sulfuric acid is used as the acid, the guanidinium salt does not precipitate by cooling, and thus the above filtration may be omitted and the extraction operation with an organic solvent may be performed directly.

  In any of the above cases, the aqueous phase is further extracted with an extraction solvent, and the obtained extraction solvent phase is combined with the previously obtained extraction solvent phase. After the extraction solvent is distilled off from the combined extraction solvent phase, the target pyridylethanethiol compound can be obtained by distillation under reduced pressure.

  The greatest feature of the present invention is that, in the method for producing a pyridylethanethiol compound by reacting vinylpyridines with a sulfur-containing compound as in the above-described example, a vinylpyridine having a polymer content of 2% by weight or less is produced. In the present invention, in the present invention, a pyridylethanethiol compound can be produced in high yield without causing the problem of sticking matter by using such vinylpyridines having a low polymer content.

  Next, a pyridylethane thiol compound produced by such a method for producing a pyridylethane thiol compound of the present invention (hereinafter sometimes referred to as “pyridylethane thiol compound of the present invention”) or a thiol group is protected. An acidic catalyst obtained by modifying the sulfonic acid group of the sulfonic acid type cation exchange resin using the pyridylethanethiol compound of the present invention will be described.

  The sulfonic acid type cation exchange resin used for this modification is one in which a sulfonic acid group is introduced into a styrene copolymer obtained by a copolymerization reaction of a polymerizable monomer containing a styrene monomer and a crosslinkable monomer.

  Here, the styrenic monomer is a monomer having an arbitrary substituent in a range that does not impair the function as an ion exchange resin in styrene, or a benzene ring of styrene or a vinyl group of styrene, but polyester, polycarbonate, polyamide, It may be a polymer such as polyolefin, poly (meth) acrylic acid ester, polyether, polystyrene, or a macromonomer in which the end of the oligomer has a styryl structure. Here, “(meth) acryl” means “acryl” and “methacryl”. The same applies to “(meth) acryloyl” described later.

  As the styrene monomer, a monomer represented by the following formula (IV) is preferable.

(IV) In the formula, X ₁ , X ₂ and X _{3 each} represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, a halogen atom, an alkylsilyloxy group, a nitro group or a nitrile group, and Y is Hydrogen atom, amino group, alkylamino group, alkyl group, alkenyl group, alkynyl group, halogen atom, haloalkyl group, aryl group such as phenyl group and naphthyl group, aralkyl group such as benzyl group, alkoxyalkyl group, nitro group, alkanoyl Group, aroyl group such as benzoyl group, alkoxycarbonyl group, allylalkoxycarbonyl group, alkoxy group, haloalkoxy group, allyloxy group, aralkyloxy group, alkoxyalkyloxy group, alkanoyloxy group, alkoxycarbonyloxy group, aralkyloxycarbonyloxy Group or al A killyloxy group is shown. m is an integer from 1 to 5, and X ₁ , X ₂ , and X ₃ may be the same or different from each other, and a plurality of Ys when m is 2 or more may be the same or different.

  Specific examples of the styrenic monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, fluorostyrene, chlorostyrene, and bromo. A vinyl group such as styrene such as styrene in which a benzene ring is substituted with an alkyl group having 1 to 4 carbon atoms or a halogen atom, α-methylstyrene, α-fluorostyrene, β-fluorostyrene, or the like is used. And styrene substituted with an alkyl group or a halogen atom.

These styrene monomers may be used alone or in combination of two or more.
Of these, styrene is most preferable as the styrene monomer.

  On the other hand, the crosslinkable monomer is a compound having two or more carbon-carbon double bonds copolymerizable with the styrenic monomer in the molecule, and specifically, polyvinylbenzene such as divinylbenzene and trivinylbenzene, divinyl. 2 or more benzene rings such as alkyldivinylbenzene such as toluene, bis (vinylphenyl), bis (vinylphenyl) methane, bis (vinylphenyl) ethane, bis (vinylphenyl) propane, bis (4-vinylphenyl) sulfone An aromatic divinyl compound having a structure in which is bonded directly or via a linking group such as an alkylene group or a styrylene group. Polymers such as polyester, polycarbonate, polyamide, polyolefin, poly (meth) acrylic acid ester, polyether, polystyrene, etc. Polymeric carbon-carbon double bonds such as styryl structure at both ends of oligomer and (meth) acrylic structure It may be a macromonomer having

These crosslinkable monomers may be used individually by 1 type, and 2 or more types may be mixed and used for them.
Among these, divinylbenzene is preferable as the crosslinkable monomer. Depending on the divinylbenzene, ethylvinylbenzene (ethylstyrene) may be produced as a by-product when it is produced, and this divinylbenzene may be used in the present invention. can do.

  The polymerizable monomer used for the production of the styrenic copolymer contains the styrenic monomer and the crosslinkable monomer, but additionally contains other monomers that can be polymerized therewith as necessary. Also good. Specific examples of such polymerizable monomers (hereinafter sometimes referred to as “third monomers”) include polycyclic aromatic skeletons such as naphthalene, anthracene, and phenanthrene, such as vinylnaphthalene and vinylanthracene. Vinyl monomers; (meth) acrylic acid esters such as methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate; diene hydrocarbon compounds such as butadiene and isoprene; α-olefins such as 1-pentene and 1-hexene ; (Meth) acrylonitrile and the like. These may be used alone or in combination of two or more.

  In addition, by using such a third monomer, an effect such as an increase in oxidation resistance can be obtained. In this case, the amount used is usually 50 mol% or less with respect to the styrene monomer, preferably It is 20 mol% or less, and particularly preferably 10 mol% or less. If the amount of the third monomer used is too large, the amount of the sulfonic acid group per unit weight that can be introduced into the resulting copolymer decreases, and the desired catalytic activity may not be obtained.

  The degree of crosslinking of the styrene copolymer obtained by polymerizing a polymerizable monomer containing a styrene monomer and a crosslinkable monomer is preferably 1% or more, more preferably 2% or more, and preferably 8% or less, 5% The following is more preferable. The degree of cross-linking here refers to the concentration of the cross-linkable monomer in the polymerizable monomer to be subjected to polymerization on the weight basis, and is the same as the definition used in this field.

  If the degree of cross-linking is too small, it will be difficult to maintain the strength of the resulting cation exchange resin. When used as a catalyst for producing bisphenol compounds, before use, it may be used in a phenol compound or a mixed solvent of phenol compound and water before use. Swelling and shrinking when performing conditioning by bringing them into contact with each other cause crushing of the cation exchange resin. On the other hand, if the degree of crosslinking is too large, the resulting copolymer particles are less likely to swell, and thus diffusion resistance within the copolymer particles is likely to occur, resulting in a significant decrease in catalyst activity.

  The copolymerization reaction of a polymerizable monomer containing a styrene monomer and a crosslinkable monomer can be performed based on a known technique using a radical polymerization initiator.

  As the radical polymerization initiator, one or more of benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, azobisisobutyronitrile and the like are used. Usually, the weight of the polymerizable monomer (total monomer) Weight) to 0.05 wt% or more and 5 wt% or less.

  The polymerization mode is not particularly limited, and can be performed in various modes such as solution polymerization, emulsion polymerization, suspension polymerization, etc., and classification with a sieve can be performed as necessary.

  The polymerization temperature in the copolymerization reaction is usually room temperature (about 18-25 ° C.) or higher, preferably 40 ° C. or higher, more preferably 70 ° C. or higher, and usually 250 ° C. or lower, preferably 150 ° C. or lower, more preferably 140. It is below ℃. If the polymerization temperature is too high, depolymerization occurs at the same time, and the degree of polymerization completion is reduced. If the polymerization temperature is too low, the degree of polymerization completion will be insufficient.

  The polymerization atmosphere can be carried out under air or an inert gas, and nitrogen, carbon dioxide, argon or the like can be used as the inert gas.

  The method of introducing a sulfonic acid group into the styrene copolymer obtained by the above copolymerization reaction (sulfonation) is not particularly limited, and can be performed according to a conventional method.

  For example, in the absence of an organic solvent, or in the presence of an organic solvent such as benzene, toluene, xylene, nitrobenzene, chlorobenzene, tetrachloromethane, dichloroethane, trichloroethylene, propylene dichloride, the copolymer is treated with sulfuric acid, chlorosulfonic acid, It is carried out by reacting with a sulfonating agent such as fuming sulfuric acid. Here, as for an organic solvent and a sulfonating agent, all may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The reaction temperature at this time is usually about 0 to 150 ° C., and is appropriately selected according to the sulfonating agent and the organic solvent to be used.

  The sulfonated copolymer is separated by washing, isolation, etc. according to a conventional method to obtain a sulfonic acid type strongly acidic cation exchange resin.

In the present invention, the exchange capacity (amount of sulfonic acid group) as the strongly acidic cation exchange resin is usually 0.5 meq / mL or more, preferably 1.0 meq / mL or more per unit volume of the water-containing resin. On the other hand, it is usually 3.0 meq / mL or less, preferably 2.0 meq / mL or less. In the dry state resin, it is usually 1.0 meq / g or more, preferably 2.0 meq / g or more per unit volume, and usually 6.0 meq / g or less, preferably 5.5 meq / g or less. is there. In the wet state in which the adhering water is removed from the water-containing resin, it is usually 0.5 meq / g or more, preferably 1.0 meq / g or more, while usually 3.0 meq / g or less, preferably 2.0 meq / g. It is as follows. If the exchange capacity is too low, the catalyst activity is insufficient, and a cation exchange resin having an excessively high exchange capacity is difficult to produce.
The exchange capacity of this strongly acidic cation exchange resin is, for example, “Diaion, Ion Exchange Resin / Synthetic Adsorbent Manual 1” (Mitsubishi Chemical Corporation, 4th revised edition, published on October 31, 2007, 133-135). Page) or a method according to this method.

  The main form of the sulfonic acid type cation exchange resin used here includes a gel type and a porous type (MR type: macroreticular type). Therefore, the gel type is preferable. In addition, a porous type (a porous type, a high porous type, or a macroporous type) is also preferable from the viewpoint of ensuring substance diffusibility, resin durability, and strength. The gel type includes a simple gel type copolymer and an expanded network type gel copolymer, both of which can be used. On the other hand, the MR type is a porous copolymer and can be used with any surface area, porosity, average pore diameter, and the like.

  A conventionally known method can be used as the gel-type or porous-type sulfonic acid-type exchange resin. For example, “Ion-exchange resin, its technology and application” (Organo Corporation, revised edition, 1986) 16th issue, pages 13 to 21).

  The method for modifying the obtained sulfonic acid type cation exchange resin with the pyridylethanethiol compound of the present invention is not particularly limited, and as a typical method, the pyridylethanethiol compound of the present invention can be modified with an aqueous solvent or an organic solvent. Among them, there is a method of reacting with a cation exchange resin and ion-bonding to a sulfonic acid group of the cation exchange resin. Specifically, a solution in which the pyridylethanethiol compound is dissolved in an appropriate solvent such as water, alcohol, ketone, ether, phenol, or a pyridylethanethiol compound not diluted with the solvent is directly dispersed in the solvent. And a method of mixing and stirring the cation exchange resin by a method such as dropping. By this method, a part of the sulfonic acid group of the cation exchange resin and the pyridylethanethiol compound react with each other to be neutralized by ionic bonding and modification.

  In modification, the pyridylethanethiol compound of the present invention may be used alone or in combination of two or more.

  The pyridylethanethiol compound of the present invention is excellent in the effect of improving the conversion rate and selectivity as a co-catalyst during the production of the bisphenol compound. Among them, 2- (2-pyridyl) ethanethiol and 2- (4-pyridyl) are particularly preferred. Ethanethiol is more preferable because it improves the conversion rate and selectivity and reduces the decrease in activity when used over a long period of time.

  As the pyridylethanethiol compound of the present invention, it is preferable to use a purified high-purity compound, but impurities such as disulfide can be used as long as the reaction is not significantly inhibited when a strongly acidic cation exchange resin after modification is used as a catalyst. May be included. Moreover, in order to suppress the production | generation of such an impurity, you may use what is stabilized as a salt with mineral acids, such as hydrochloric acid and a sulfuric acid.

  When using the pyridylethanethiol compound of the present invention in which the thiol group is protected, the protecting group for the thiol group is not particularly limited as long as it is a group capable of protecting the thiol group. For example, “Green's Protective Groups in Organic” Protection can be achieved by using the protecting group and protecting method described in “Synthesis, Fourth Edition, Wiley (2007)”. Specific examples include thioethers protected with aliphatic protecting groups that generate stable carbocations such as tert-butyl groups, thioesters protected with acyl protecting groups such as acetyl groups, and protected with carbonate protecting groups. Examples include thiocarbonates, benzylthioethers protected with benzyl protecting groups, dithioacetals protected with ketones and aldehydes, and the like.

  In addition, the ratio (modification rate) of modifying the cation exchange resin with the pyridylethanethiol compound of the present invention or the pyridylethanethiol compound of the present invention in which the thiol group is protected is the total sulfonic acid group of the sulfonic acid type cation exchange resin. It is preferable to set it as 3 mol% or more, and it is more preferable to set it as 5 mol% or more. Further, it is preferably 70 mol% or less, more preferably 50 mol% or less, and more preferably 30% or less. As a result, the effect of the thiol compound acting as a co-catalyst can be maximized without causing a decrease in catalytic activity due to a decrease in the amount of sulfonic acid groups required for the condensation reaction during the production of the bisphenol compound. When the modification rate is too small, the reactivity improvement effect tends to be low, and the activity and life as a catalyst tend to be insufficient. On the other hand, when the modification rate is too large, the amount of sulfonic acid groups involved in the reaction decreases, and the reactivity tends to decrease. Moreover, since many expensive thiol compounds are used, it is not economically preferable.

  Next, a method for producing a bisphenol compound by subjecting a phenol compound and a carbonyl compound to a condensation reaction using the above acidic catalyst will be described.

  The condensation reaction between a phenol compound and a carbonyl compound is considered to utilize the strong ortho-para orientation of the phenolic hydroxyl group, particularly the para orientation, and therefore the phenol compound used has a substituent at the ortho or para position. None is preferred. Among them, the bisphenol compound which is a condensation reaction product is generally preferably a 4,4'-bisphenol compound from the viewpoint of its use, and from this point, it is preferable to use a phenol compound having no substituent at the para position.

  When the phenol compound has a substituent, the substituent does not inhibit the ortho-para orientation of the phenolic hydroxyl group, and the use of the resulting bisphenol compound as long as it does not sterically hinder the condensation position of the carbonyl compound. It may be arbitrary depending on the physical properties. Typical examples of the substituent include a lower alkyl group having 1 to 4 carbon atoms. Moreover, the compound of the same substitution position can be used also about the phenol compound which substituted halogen atoms, such as a fluorine atom, a chlorine atom, and a bromine atom, instead of this substituent. The number of substituents may be one or more.

  Specific examples of the phenol compound include phenol (unsubstituted phenol), o-cresol, m-cresol, 2,5-xylenol, 2,6-xylenol, 2,3,6-trimethylphenol, 2 , 6-di-tert-butylphenol, o-chlorophenol, m-chlorophenol, 2,5-dichlorophenol, 2,6-dichlorophenol and the like. Of these, phenol is particularly preferred.

  On the other hand, the carbonyl compound is not particularly limited, but specific examples include ketones having about 3 to 10 carbon atoms such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone, acetophenone, and formaldehyde, acetaldehyde, propion. Examples include aldehydes having about 1 to 6 carbon atoms such as aldehyde and butyraldehyde. Of these, acetone is preferred.

  When phenol is used as the phenol compound and acetone is used as the carbonyl compound, bisphenol A useful as a raw material for polycarbonate resin and the like can be obtained, which is particularly preferable.

  The molar ratio of the phenol compound and the carbonyl compound used as a raw material for the condensation reaction is usually 2 mol or more, preferably 4 mol or more, and usually 40 mol or less, preferably 30 mol or less, with respect to 1 mol of the carbonyl compound. If the amount of phenolic compound used is too small, there is a tendency for by-products to increase. On the other hand, if the amount is too large, there is almost no change in the effect, but rather the amount of phenolic compound that is recovered and reused is economical. There is a tendency to disappear.

  When performing a condensation reaction between a phenol compound and a carbonyl compound, it is possible to arbitrarily select a continuous method, a semi-continuous method, a batch method, or the like according to the production amount, restrictions on the apparatus, etc. A single method may be used, and a method in which a plurality of reactors are connected in parallel or in series, or a combination of these methods and reactors may be used. These production methods may be a single reaction method. As another method, for example, a method in which a continuous method and a batch method are performed in parallel using a plurality of reactors can be selected.

  In the reaction, the phenol compound and the carbonyl compound may be supplied separately to the reactor, or may be mixed and supplied. Further, the carbonyl compound may be subjected to the reaction at the start of the reaction or may be divided into a plurality of times for the reaction.

  Moreover, when reacting a phenol compound and a carbonyl compound, the pyridylethane thiol compound of the present invention used for the above-mentioned modification, other thiol compounds and / or a thiol compound that cannot be used for modification may be allowed to coexist. Good. Here, “a thiol compound that cannot be used for modification” contains a thiol group or a protected thiol group, but does not contain a functional group that can ionically bond with a sulfonic acid group of a cation exchange resin. It refers to a thiol compound, and examples thereof include alkanethiols such as methanethiol and ethanethiol. These may use 1 type, may use multiple types, may be made to melt | dissolve in a phenol compound and / or a carbonyl compound for a reaction, or may supply separately from a phenol compound and / or a carbonyl compound.

  As the reaction apparatus, various apparatuses such as a reactor having a heating apparatus and a cooling apparatus and an adiabatic reactor can be used as necessary.

  In the production of a bisphenol compound, a continuous method is preferable as a reaction method from the viewpoint of reaction efficiency and ease of operation. The continuous method is not particularly limited as long as it is a method in which a reaction is performed by continuously supplying a phenol compound and a carbonyl compound to a reactor filled with an acidic catalyst. For example, a fixed bed flow system, a fluidized bed, and the like. Either a system or a continuous stirring system may be used, but a fixed bed circulation system in which an acidic catalyst is used as a fixed bed and a phenol compound and a carbonyl compound are continuously supplied and distributed is preferable.

When the condensation reaction is performed by a fixed bed flow system, a fluidized bed system, or a continuous stirring system, the feed of the phenol compound and the carbonyl compound as raw materials is based on an acidic catalyst in a wet state of the phenol compound, and the phenol compound and the carbonyl compound. total normal liquid hourly space velocity of the compound (LHSV) 0.05hr ^-1 or more, preferably at 0.2 hr ^-1 or more and usually 20 hr ^-1 or less, preferably at 10 hr ^-1 or less. In particular, when the reaction is carried out in a fixed bed flow system, a screen or the like is provided on the upper and / or lower part of the apparatus as necessary so that only the reaction liquid can flow without the packed acidic catalyst flowing out of the apparatus. Also good. The raw material may flow from the upper part to the lower part of the reactor (down flow type) or from the lower part to the upper part of the apparatus (up flow type). In the fixed bed flow system, there are known problems such as the fluidization of the catalyst and the accompanying catalyst outflow in the upflow system, and the pressure loss (differential pressure) in the downflow system. In view of these problems, an appropriate method may be selected each time. This pressure loss can be selected in an appropriate range according to the amount of catalyst, LHSV, the capacity of the equipment used, and the like.

  The reaction temperature in the production of the bisphenol compound is usually carried out at a temperature at which the reaction solution can exist in a liquid state without solidifying. For example, when the phenol compound is phenol, it is 40 ° C. or higher, preferably 50 ° C. or higher. The higher the reaction temperature is, the more advantageous the reaction rate is, but from the viewpoint of the heat resistance temperature of the acidic catalyst, it is preferable to carry out the reaction under conditions such that the maximum temperature in the reactor is 120 ° C. or less, particularly 100 ° C. or less. If the reaction temperature is high, the sulfonic acid group is eliminated due to partial decomposition even at a temperature lower than the heat resistant temperature of the acidic catalyst. From this point of view, the lowest possible temperature is preferable. The produced bisphenol compound may solidify.

  When an acidic catalyst is subjected to a condensation reaction between a phenolic compound and a carbonyl compound, if water remains in the acidic catalyst, it becomes a hindrance to the reaction, so the water in the acidic catalyst must be removed before use in the reaction. For example, a method of removing water in the acidic catalyst by contacting with a phenol compound as a raw material is preferable. By such treatment, the induction period at the start of the reaction is shortened and can be used for the reaction promptly.

  Phenol compounds used in the method for producing bisphenol compounds (phenol compounds other than those recovered and used in the bisphenol compound production process described later) can be used as long as they have high purity, but after purification It is preferred to use. The method for purifying the phenol compound is not particularly limited. For example, the phenol compound is brought into contact with an acidic catalyst such as a general sulfonic acid-type cation exchange resin at 40 to 110 ° C., and impurities contained in the phenol compound are overlapped. For example, a method of removing heavy components by distilling after the material has been refined may be used. The phenol compound thus obtained can be used as a reaction raw material by supplying it to the reactor.

  Moreover, as a phenol compound used for manufacture of a bisphenol compound, it is also possible to recycle and use what was collect | recovered at the manufacturing process of a bisphenol compound. As an example of the phenol compound recycled, the phenol solution which isolate | separated the target bisphenol compound from the reaction product liquid can be mentioned. Specifically, a phenol solution generally called a “mother liquor” obtained when a bisphenol compound is solidified by crystallization, etc., and separated by a solid-liquid separation method in a solid-liquid separation step. In addition, other examples include phenol solutions separated by distillation and the like, but are not limited thereto.

In addition, the phenol compound refine | purified as mentioned above can also be used by a desired method according to processes, such as using as a washing | cleaning liquid of the crystal | crystallization obtained at the solid-liquid separation process, and recycling to a reactor with mother liquid.
At that time, it is preferable to separate the whole or a part and treat with an acid or alkali catalyst to remove impurities such as heavy components, or recover the bisphenol compound and use it as a raw material for the condensation reaction. When the phenol compound recovered in the process is recycled and used as a washing liquid for crystals obtained in the solid-liquid separation step, it is preferably used after purification.

  In small scales such as laboratories, only purified high-purity phenol compounds may be used as the phenol compound used as a raw material. However, in industrial scales, phenol compounds recovered in the process are usually recycled. It is economically advantageous to use it.

  The reaction solution produced by the above method contains a large excess of phenolic compound, unreacted carbonyl compound, impurities generated during the condensation reaction, etc. together with the desired bisphenol compound. It is necessary to take out the target bisphenol compound. The method for separating and purifying the target bisphenol compound from the reaction solution is not particularly limited and is performed according to a known method. The following is a representative example of the separation and purification method, taking the case where the target material is bisphenol A as an example. Explained.

  Subsequent to the condensation reaction, in the low boiling point component separation step, the reaction liquid obtained by the condensation reaction includes a component containing bisphenol A and phenol, a low boiling point component containing water, unreacted acetone, and the like by-produced in the reaction. To separate. The low boiling point component separation step is preferably performed by a method of separating the low boiling point component by distillation under reduced pressure, and the low boiling point component may contain phenol or the like. The component containing bisphenol A and phenol can adjust the concentration of bisphenol A to a desired concentration by removing phenol by distillation or adding phenol as necessary.

  Subsequently, a slurry containing crystals of an adduct of bisphenol A and phenol is obtained in the crystallization step. The concentration of bisphenol A, which is a component containing bisphenol A and phenol used in the crystallization step, is preferably 10 to 30% by weight from the viewpoint of ease of handling of the resulting slurry. Examples of crystallization methods include a method of directly cooling a component containing bisphenol A and phenol, a method of cooling by mixing other solvent such as water and evaporating the solvent, and further removing phenol. In order to obtain an adduct having a desired purity, crystallization may be performed once or twice or more. The slurry obtained in the crystallization step is solid-liquid separated into an adduct crystal and a mother liquor by vacuum filtration, pressure filtration, centrifugal filtration, etc. in a solid-liquid separation step, and an adduct crystal of bisphenol A and phenol. Is recovered. In the crystallization step, the crystal of bisphenol A can be directly obtained by crystallization by adjusting the composition and crystallization conditions of the component containing bisphenol A and phenol used for crystallization.

  By removing the phenol by melting the adduct crystals obtained in the solid-liquid separation step in the subsequent dephenol step, after melting, by means of flash distillation, thin film distillation, steam stripping, etc. alone or in combination. A high purity molten bisphenol A is obtained. The removed phenol is purified as desired, and can be used for the reaction, washing of crystals of the adduct obtained in the solid-liquid separation step, and the like. Although the obtained high-purity molten bisphenol A is solidified in the granulation step, a method of obtaining a small spherical bisphenol A prill by spraying from a nozzle and contacting with a cooling gas is preferable. In addition, it can crystallize again from the crystal | crystallization of the adduct obtained at the solid-liquid separation process, without passing through a phenol removal process, and can also obtain only bisphenol A by crystallization.

  Further, for the purpose of preventing accumulation of impurities in the system, at least a part of the mother liquor separated in the solid-liquid separation step can be treated in the impurity treatment step. For example, it is economical to mix an alkali or acid, heat and then distill to separate light and heavy components, and use the light component for the reaction after recombination treatment with an acid catalyst or the like. However, it is preferable. Here, by purging the heavy component out of the system, accumulation of impurities can be prevented and the purity of the product can be improved. The recovery rate of bisphenol A can also be improved by crystallization after isomerization of at least a part of the mother liquor using an acid catalyst.

  The low boiling point component obtained in the low boiling point component separation step can separate and recover unreacted acetone by the acetone circulation step and circulate the collected acetone to the reaction step.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

  In the following, the polymer contained in 2-vinylpyridine used as a raw material for producing 2- (2-pyridyl) ethanethiol was quantified by the following GPC method and / or reprecipitation method.

<GPC method>
It measured on the following conditions by the gel permeation chromatography (GPC). The calibration curve used for the determination of the polymer content was prepared using a poly-2-vinylpyridine standard sample (manufactured by Polymer source, Inc .: Mn = 10000, Mw = 10800, Mw / Mn = 1.08), and an absolute calibration curve. The polymer content with a standard polystyrene equivalent molecular weight of 2000 or more was quantified by the method.

Equipment: “LC-10AS” manufactured by Shimadzu Corporation
UV detector: “SPD-10A” manufactured by Shimadzu Corporation
Column: “TSKgel G2000HXL” (7.8 mmφ × 300 mm) manufactured by Tosoh Corporation
Mobile phase: Tetrahydrofuran (for HPLC)
Flow rate: 0.8mL / min
Column temperature: 40 ° C
Detection wavelength: 254 nm
Sample: 100 volume dilution

<Reprecipitation method>
To 2-vinylpyridine W1 (g), 10 times by weight of n-hexane (purity 99.5% or more) was added and stirred. The deposited precipitate was filtered using a membrane filter having a pore size of 0.1 μm (“H010A047A” manufactured by Toyo Roshi Kaisha, Ltd.), and then the obtained precipitate was dried with a constant-temperature vacuum dryer at 60 ° C. for 3 hours. The polymer content W2 (g) contained in 2-vinylpyridine was recovered, and the polymer content was calculated using the following formula.
Polymer content (% by weight) = 100 × W2 (g) / W1 (g)

  Moreover, the purity of the 2- (2-pyridyl) ethanethiol crude product produced from 2-vinylpyridine was determined by gas chromatography (GC) analysis under the following conditions.

<GC analysis>
Gas chromatography: “GC-2014” manufactured by Shimadzu Corporation
Column: “TC-5” (60 m × 0.32 mm × 1.00 μm) manufactured by GL Sciences
Detector: FID
Carrier gas: He

[Example 1]
2- (2-pyridyl) ethanethiol was produced using 2-vinylpyridine having a polymer content of 0.24% by weight as measured by GPC method. A jacketed four-necked separable flask (capacity: about 700 mL) was equipped with a stirring motor, a Dimroth condenser with a nitrogen gas inlet tube, and a thermometer, and 254.2 g (0.75 mol) of 29 wt% sulfuric acid aqueous solution And 27.2 g (0.36 mol) of thiourea were charged. In a nitrogen atmosphere, while stirring, warm water was passed through the jacket and heated to 70 ° C., and then 30.0 g (0.29 mol) of 2-vinylpyridine was added dropwise over about 2 hours using a syringe pump. The reaction was continued for 5 hours while maintaining the temperature.

  The reaction solution was cooled to room temperature, 51.7 g of toluene was added, and the reaction solution was further cooled to 20 ° C. Under stirring, 108.4 g of 28 wt% aqueous ammonia (1.78 mol as ammonia) was added dropwise to the reaction solution over about 2 hours, taking care not to raise the liquid temperature. After completion of the dropwise addition, the temperature was raised to 40 ° C. and further stirred for 3 hours. After the stirring was stopped, the reaction solution was transferred to a separatory funnel and separated into two phases. The upper phase (toluene phase) was taken out, and the lower phase (aqueous phase) was extracted twice with 51.7 g of toluene.

  When the solid content adhering to the inner wall of the flask and the stirring blade was scraped and recovered, the recovered amount was 0.62 g, and the ratio to the charged 2-vinylpyridine was 2.1% by weight.

  Moreover, all the said toluene phases were collected, and 36.6 g (purity) of 2- (2-pyridyl) ethanethiol crude product was obtained by distilling toluene off with a rotary evaporator at a bath temperature of 30 to 60 ° C. and a pressure of 1.0 kPa. 94.2%). The yield of 2- (2-pyridyl) ethanethiol with respect to 2-vinylpyridine charged was 86.8%.

[Comparative Example 1]
Except that 2-vinylpyridine having a polymer content measured by GPC method of 2.76% by weight and a polymer content measured by reprecipitation method of 2.58% by weight was used as a raw material, Example In the same manner as in 1, 2- (2-pyridyl) ethanethiol was synthesized.

The recovered amount of the solid content adhering to the inner wall of the flask and the stirring blade was 2.46 g, and the ratio to the charged 2-vinylpyridine was 8.2% by weight.
The amount of the crude 2- (2-pyridyl) ethanethiol product obtained was 33.8 g (purity 93.8%), and the yield based on the charged 2-vinylpyridine was 79.8%. .

[Example 2]
The 2-vinylpyridine used in Comparative Example 1 was purified by simple distillation (temperature 43 ° C., pressure 1.5 kPa). The purified 2-vinylpyridine polymer was measured by the GPC method, but no polymer was detected. 2- (2-pyridyl) ethanethiol was synthesized in the same manner as in Example 1 except that 2-vinylpyridine was used as a raw material.

The recovered amount of the solid adhering to the inner wall of the flask and the stirring blade was 0.20 g, and the ratio to the charged 2-vinylpyridine was 0.7% by weight.
The amount of the obtained 2- (2-pyridyl) ethanethiol crude product was 35.5 g (purity 95.0%), and the yield based on the charged 2-vinylpyridine was 84.9%. .

[Example 3]
2- (2-pyridyl) ethanethiol was synthesized in the same manner as in Example 1 except that 2-vinylpyridine, whose polymer content was not detected by the GPC method and reprecipitation method, was used as a raw material.

The recovered amount of the solid adhering to the inner wall of the flask and the stirring blade was 0.03 g, and the ratio to the charged 2-vinylpyridine was 0.1% by weight.
The amount of the crude 2- (2-pyridyl) ethanethiol product obtained was 35.3 g (purity 96.5%), and the yield based on the charged 2-vinylpyridine was 85.8%. .

The results of Examples 1 to 3 and Comparative Example 1 are summarized in Table 1.
From Table 1, it can be seen that according to the present invention, it is possible to produce a high-purity pyridylethanethiol compound in a high yield while suppressing the formation of fixed substances in the production facility.

Claims (3)

  A method for producing a pyridylethanethiol compound, wherein vinylpyridines and a sulfur-containing compound are used as raw materials, wherein the polymer contained in the vinylpyridines is 2% by weight or less. A method for producing a pyridylethanethiol compound.   The method for producing a pyridylethanethiol compound according to claim 1, wherein the polymer contained in the vinylpyridines is 100 ppm by weight or more.   The pyridylethanethiol according to claim 1 or 2, wherein the vinylpyridine is 2-vinylpyridine, the sulfur-containing compound is thiourea, and the pyridylethanethiol compound is 2- (2-pyridyl) ethanethiol. Compound production method.