Method for producing triarylsulfonium compound

Abstract

The present invention addresses the problem of providing a method for producing a sulfonium salt that is composed of a triarylsulfonium cation having an electron-withdrawing group and a halide ion, wherein the purity of the sulfonium salt in an obtained product is excellent.　A method for producing a triarylsulfonium compound according to the present invention is for obtaining a compound represented by formula (4) by reacting a compound represented by formula (1) with a compound represented by formula (2) so as to obtain a compound represented by formula (3), and subsequently reacting the compound represented by formula (3) with a hydrogen halide.

Description

Method for producing triarylsulfonium compounds

[0001] This invention relates to a method for producing a triarylsulfonium salt composed of a triarylsulfonium cation having an electron-withdrawing group and a halide ion.

[0002] In recent years, development of low-LUMO (Lowest Unoccupied Molecular Orbital) sulfonium salts has been progressing as compounds that cleave and generate acid upon exposure to EUV (Extreme Ultraviolet) resists (photoacid generators). One example of a low-LUMO sulfonium salt is a triarylsulfonium salt with an electron-withdrawing group. Improving the sensitivity of EUV resists is a challenge, but by using low-LUMO sulfonium salts, it becomes easier to generate acid through secondary electrons generated from the material that absorbs EUV light, thereby improving the sensitivity of the EUV resist.

[0003] Conventionally, known methods for synthesizing sulfonium salts include those using Grignard reagents and activators, and those using acids and acid anhydrides. Synthesizing low-LUMO sulfonium salts typically requires highly active reagents, such as TMS-OTf (trimethylsilyltrifluoromethanesulfonate) as the activator and Tf as the acid anhydride. ２ Since O (trifluoromethanesulfonic anhydride) must be used, the triflate anion (CF) is used as the counter anion. ３ SO ３ －It is necessary to synthesize a sulfonium salt into which ( ) is introduced. Therefore, in the production of a photoacid generator for EUV resists, after synthesizing a sulfonium salt having a triflate anion as a counter anion (hereinafter also referred to as "triflate salt"), it is necessary to further convert the triflate anion into another anion by an anion exchange reaction. That is, a method is used in which a desired salt structure is obtained by using the triflate salt as a cation source and converting the counter anion of the triflate salt into another anion. For example, in the example column of Patent Document 1, a method for synthesizing a sulfonium salt having a triflate anion (CF ３ SO ３ － ) as a counter anion by a production method using a Grignard reagent and TMS-OTf, and then producing a photoacid generator having a desired salt structure by an anion exchange reaction is disclosed. Patent Document 1 discloses a sulfonium salt having an alkylsulfonic acid fluoride ion as a counter anion, a sulfonium salt having a salicylic acid ion as a counter anion, etc. as photoacid generators obtained by the above production method.

[0004] Japanese Unexamined Patent Application Publication No. 2023-032149

[0005] On the other hand, triflate salts often do not have sufficient exchange activity with other anions, and there is a problem that triflate salts tend to remain in the target product. In addition, since the remaining triflate salt is difficult to remove, there are limitations in its use as a cation source.

[0006] Incidentally, sulfonium salts that have high anion exchange activity and are easily usable as cation sources include, for example, sulfonium salts (hereinafter also referred to as "halogen salts") that have halide ions such as chloride ions and bromide ions as counteranions. For this reason, converting triflate salts into halogen salts that have high anion exchange activity and are easily usable as cation sources through an anion exchange reaction can further improve their suitability as raw material components for photoacid generators for EUV resists. A common method for obtaining halogen salts from triflate salts is to use an anion exchange resin column. However, although this method using anion exchange resin columns is highly versatile and leaves little triflate salt residue, the use of a column imposes limitations on equipment when producing on an industrial scale. Against this backdrop, there is a need for the development of a manufacturing method that can easily produce low LUMO sulfonium salts having halide ions as counteranions without equipment limitations.

[0007] The present inventors focused on the sulfonium salt (hereinafter also referred to as "salicylate") having a salicylate anion as a counteranion, as described in Patent Document 1, and investigated a method of converting a salicylate obtained from a triflate salt into a halogen salt by further anion conversion reaction. They found that the purity of the halogen salt in the resulting product was low due to the presence of triflate salt, and that there is room for further improvement.

[0008] Therefore, the present invention aims to provide a method for producing a sulfonium salt comprising a triarylsulfonium cation having an electron-withdrawing group and a halide ion, wherein the resulting product has excellent purity.

[0009] The inventors have found that the above problems can be solved by the following configuration.

[0010] 〔1〕A method for producing a triarylsulfonium compound, which comprises reacting a compound represented by formula (1) described below with a compound represented by formula (2) described below to obtain a compound represented by formula (3) described below, and then reacting the compound represented by formula (3) with hydrogen halide to obtain a compound represented by formula (4) described below. 〔2〕In the compound represented by formula (2) and the compound represented by formula (3), R １６ represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms, or n represents an integer of 2 or more, and two adjacent R １６ are bonded to each other to form an aromatic ring. The method for producing a triarylsulfonium compound according to [1]. 〔3〕In the compound represented by formula (2) and the compound represented by formula (3), R １６ represents a chlorine atom, a bromine atom, an alkyl group having 1 to 6 carbon atoms, or a perfluoroalkyl group having 1 to 3 carbon atoms, or n represents an integer of 2 or more, and two adjacent R １６ are bonded to each other to form an aromatic ring. The method for producing a triarylsulfonium compound according to [1] or [2]. 〔4〕In the compound represented by formula (2) and the compound represented by formula (3), R １６A method for producing a triarylsulfonium compound according to any one of [1] to [3], wherein the compound represented by formula (2) is selected from the group consisting of the compound represented by formula (2-1), the compound represented by formula (2-2), the compound represented by formula (2-3), the compound represented by formula (2-4), and the compound represented by formula (2-5) described later. A method for producing a triarylsulfonium compound according to any one of [1] to [4]. A method for producing a triarylsulfonium compound according to any one of [5], wherein the compound represented by formula (2) is selected from the group consisting of the compound represented by formula (2-1) and the compound represented by formula (2-2). A method for producing a triarylsulfonium compound according to any one of [1] to [6], wherein the compound represented by formula (2) is selected from the group consisting of the compound represented by formula (2-1) and the compound represented by formula (2-2). A method for producing a triarylsulfonium compound according to any one of [1] to [6], wherein the ratio of the amount of compound represented by formula (1) to the amount of compound represented by formula (2) is 1 / 1 to 1 / 2 in molar ratio. [8] A method for producing a triarylsulfonium compound according to any one of [1] to [7], wherein the electron-withdrawing group in the compound represented by formula (1), the compound represented by formula (3), and the compound represented by formula (4) is selected from the group consisting of a halogen atom, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 2 to 11 carbon atoms, an alkylsulfonyl group having 1 to 10 carbon atoms, a nitrile group, and an alkoxysulfonyl group having 1 to 10 carbon atoms. [9] In the compound represented by formula (4), X － A method for producing a triarylsulfonium compound according to any one of [1] to [8], wherein the triarylsulfonium compound represents a chloride ion or a bromide ion.

[0011] According to the present invention, a method for producing a sulfonium salt comprising a triarylsulfonium cation having an electron-withdrawing group and a halide ion is provided, which offers excellent purity of the sulfonium salt in the resulting product.

[0012] The present invention will now be described in detail. The following descriptions of constituent elements may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "~" means a range that includes the numbers written before and after "~" as the lower and upper limits.

[0013] [Method for Producing Triarylsulfonium Compounds] The method for producing triarylsulfonium compounds of the present invention (hereinafter also referred to as "the method for producing the present invention") involves reacting a compound represented by formula (1) described later (hereinafter also referred to as "the triflate salt of formula (1)") with a compound represented by formula (2) described later (a salicylic acid derivative of formula (2)) to obtain a compound represented by formula (3) described later (hereinafter also referred to as "the salicylate of formula (3)"), and then reacting the compound represented by formula (3) with a hydrogen halide to obtain a compound represented by formula (4) described later (also referred to as "the halogen salt of formula (4)").

[0014] Through this study, the present inventors have found that in a manufacturing process to convert a salicylate obtained from a triflate salt into a halogen salt by further anion conversion reaction, when a predetermined substituent is introduced to the salicylic acid that serves as the anion source, the amount of triflate salt remaining in the product obtained by the anion conversion reaction from salicylate to halogen salt is significantly reduced, and the purity of the halogen salt is improved. The manufacturing method of the present invention is based on the above findings. The product obtained by the manufacturing method of the present invention has high purity of the halogen salt of formula (4) in the product, and the content of triflate salt of formula (1) remaining in the product is significantly reduced. In this specification, "purity of the halogen salt of formula (4) in the product" means the molar content of the halogen salt of formula (4) when the molar content (mol%) of each component is calculated relative to the total amount of the target halogen salt of formula (4) and the raw material components triflate salt of formula (1) and salicylic acid derivative of formula (2) in the product. In other words, for example, the product obtained by the manufacturing method of Example 1 described later has a composition in molar terms of 95 mol% of the halogen salt of formula (4), which is the target product, 5 mol% of the triflate salt of formula (1), and 0 mol% of the salicylic acid derivative of formula (2). The purity of the halogen salt of formula (4) in the product obtained by the manufacturing method of Example 1 is 95 mol%. In the product obtained by the manufacturing method of the present invention, the salicylate of formula (3) that is generated as an intermediate substance is typically not likely to remain, and its molar content is likely to be below the detection limit. The molar content of each component in the product may be determined by performing a compositional analysis on the isolated product, or by performing a compositional analysis on a solution obtained by adding an internal standard substance (e.g., p-toluenesulfonic acid monohydrate) to the reaction solution containing the product (e.g., the aqueous layer containing the product after treatment such as liquid-liquid extraction). The compositional analysis of the composition is １ 1H NMR and １９ This can be carried out by F NMR. The product in the manufacturing method of the present invention is a substance obtained through the synthesis of the halogen salt of formula (4), and does not contain a solvent.

[0015] In this specification, the molar content of the triflate salt of formula (1) in the product is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 1 mol% or less, relative to the total amount of the halogen salt of formula (4), which is the target product, and the starting components, the triflate salt of formula (1) and the salicylic acid derivative of formula (2). The lower limit is 0 mol% or more.

[0016] Furthermore, as will be described later, the manufacturing method of the present invention has been confirmed to be excellent in terms of yield of the halogen salt of formula (4).

[0017] In this specification, a higher purity of the halogen salt of formula (4) in the product obtained by the manufacturing method of the present invention is also referred to as "the effect of the present invention is superior."

[0018] Below, we will first describe in detail the compounds represented by formulas (1) to (4).

[0019] [The compound represented by formula (1) (the triflate salt of formula (1)]

[0020] In formula (1), R １ ~R １５ Each of these independently represents a hydrogen atom or an electron-withdrawing group. However, R １ ~R １５ At least one of these represents an electron-withdrawing group.

[0021] In formula (1), R １ ~R ５ At least one of the following, and R ６ ~R １０ Preferably, at least one of them represents an electron-withdrawing group, R １ ~R ５ At least one of R ６ ~R １０ At least one of the following, and R １１ ~R １５ It is more preferable that at least one of them represents an electron-withdrawing group. In particular, R is suitable as a cation source for photoacid generators for EUV resists. １ ~R ５ At least two of the following, R ６ ~R１０ At least two of the following, and R １１ ~R １５ It is even more preferable that at least two of these represent electron-withdrawing groups.

[0022] Examples of electron-withdrawing groups include halogen atoms, carbon-1 to carbon-10 fluoroalkyl groups, carbon-1 to carbon-10 fluoroalkoxy groups, carbon-2 to carbon-11 alkoxycarbonyl groups, carbon-1 to carbon-10 alkylsulfonyl groups, nitrile groups, and carbon-1 to carbon-10 alkoxysulfonyl groups.

[0023] Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with fluorine atoms or iodine atoms being preferred.

[0024] A fluoroalkyl group having 1 to 10 carbon atoms may have at least one hydrogen atom substituted with a fluorine atom, and it is preferable that all hydrogen atoms are substituted with fluorine atoms (i.e., it is a perfluoroalkyl group). The number of carbon atoms in a fluoroalkyl group having 1 to 10 carbon atoms is preferably 1 to 8, more preferably 1 to 6, and even more preferably 1 to 3. A fluoroalkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic, but linear or branched is preferred. A fluoroalkyl group having 1 to 10 carbon atoms may further have substituents.

[0025] A fluoroalkoxy group having 1 to 10 carbon atoms may have at least one hydrogen atom substituted with a fluorine atom, and it is preferable that all hydrogen atoms are substituted with fluorine atoms (a perfluoroalkoxy group). The number of carbon atoms in the fluoroalkoxy group having 1 to 10 carbon atoms is preferably 1 to 8, more preferably 1 to 6, and even more preferably 1 to 3. The fluoroalkoxy group having 1 to 10 carbon atoms may be linear, branched, or cyclic, but linear or branched is preferred. The fluoroalkoxy group having 1 to 10 carbon atoms may further have substituents.

[0026] The alkoxycarbonyl group having 2 to 11 carbon atoms preferably has 2 to 8 carbon atoms, more preferably 2 to 6, and even more preferably 2 to 3 carbon atoms. The alkoxycarbonyl group having 2 to 11 carbon atoms may be linear, branched, or cyclic, but linear or branched is preferred. The alkoxycarbonyl group having 2 to 11 carbon atoms may further have substituents.

[0027] The alkylsulfonyl group having 1 to 10 carbon atoms preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms. The alkylsulfonyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic, but linear or branched is preferred. The alkylsulfonyl group having 1 to 10 carbon atoms may further have substituents.

[0028] The alkoxysulfonyl group having 1 to 10 carbon atoms preferably has 1 to 8 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3 carbon atoms. The alkoxysulfonyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic, but linear or branched is preferred. The alkoxysulfonyl group having 1 to 10 carbon atoms may further have substituents.

[0029] [Compound represented by formula (2) (salicylic acid derivative of formula (2))]

[0030] In formula (2), R １６ R represents a halogen atom, an alkyl group having 1 to 10 carbon atoms, or a fluoroalkyl group having 1 to 10 carbon atoms. １６ Examples of halogen atoms represented by include fluorine, chlorine, bromine, and iodine atoms, with chlorine or bromine atoms being preferred.

[0031] R １６ The number of carbon atoms in the C1-C10 alkyl group represented by is preferably 1-8, more preferably 1-6, and even more preferably 1-3. The C1-C10 alkyl group may be linear, branched, or cyclic, but linear or branched is preferred. １６ The alkyl group having 1 to 10 carbon atoms represented by may further have substituents.

[0032] R１６ A fluoroalkyl group having 1 to 10 carbon atoms represented by may have at least one hydrogen atom substituted with a fluorine atom, and it is preferable that all hydrogen atoms are substituted with fluorine atoms (it is a perfluoroalkyl group). The number of carbon atoms in the fluoroalkyl group having 1 to 10 carbon atoms is preferably 1 to 8, more preferably 1 to 6, and even more preferably 1 to 3. The fluoroalkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic, but linear or branched is preferred. １６ The fluoroalkyl group having 1 to 10 carbon atoms represented by may further have substituents.

[0033] n represents an integer between 1 and 4. n is preferably 1 or 2.

[0034] If n represents an integer greater than or equal to 2, there are multiple R's. １６ These may be the same or different from each other. Also, two adjacent R １６ They may be bonded to each other to form an aromatic ring. Two adjacent R １６ The aromatic ring formed by the bonding of these elements may be monocyclic or polycyclic, but monocyclic is preferred. Furthermore, the aromatic ring is preferably an aromatic hydrocarbon ring, and more preferably a benzene ring.

[0035] R １６ In particular, in terms of the superior effects of the present invention and the superior yield of the halogen salt of formula (4), n represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms, or n represents an integer of 2 or more, and two adjacent R １６ It is preferable that they bond with each other to form an aromatic ring, and that n represents a chlorine atom, a bromine atom, an alkyl group having 1 to 6 carbon atoms, or a perfluoroalkyl group having 1 to 3 carbon atoms, or that n represents an integer of 2 or more, and that two adjacent R １６ It is more preferable that they bond with each other to form an aromatic ring, and it is even more preferable that they represent a chlorine atom, a bromine atom, an alkyl group having 1 to 6 carbon atoms, or a perfluoroalkyl group having 1 to 3 carbon atoms.

[0036] Specific examples of the compound represented by formula (2) are preferably selected from the group consisting of the compound represented by formula (2-1), the compound represented by formula (2-2), the compound represented by formula (2-3), the compound represented by formula (2-4), and the compound represented by formula (2-5). In particular, it is more preferable to select from the group consisting of the compound represented by formula (2-1) and the compound represented by formula (2-2) in terms of superior effects of the present invention and superior yield of the halogen salt of formula (4).

[0037]

[0038] [The compound represented by formula (3) (salicylate of formula (3)]

[0039] R in equation (3) １ ~R １５ R in equation (1) １ ~R １５ This is synonymous with the same as the preferred embodiment. However, R １ ~R １５ At least one of them represents an electron-withdrawing group. R in formula (3) １６ and n are R in equation (2) １６ And is synonymous with n, and the preferred embodiment is the same. Note that when n represents an integer of 2 or more, there are multiple R １６ These may be the same or different from each other. Also, two adjacent R １６ They may be bonded to each other to form an aromatic ring. Two adjacent R １６ The aromatic ring formed by the bonding of these elements may be monocyclic or polycyclic, but monocyclic is preferred. Furthermore, the aromatic ring is preferably an aromatic hydrocarbon ring, and more preferably a benzene ring.

[0040] [Compounds represented by formula (4) (halogen salts of formula (4)]

[0041] R in equation (4) １ ~R １５ R in equation (1) １ ~R １５ This is synonymous with the same as the preferred embodiment. However, R １ ~R １５At least one of them represents an electron-withdrawing group. － X represents a halide ion. － Examples of halide ions represented by include fluoride ions, chloride ions, bromide ions, and iodide ions, with chloride ions or bromide ions being preferred.

[0042] [Manufacturing Procedure] The manufacturing method of the present invention will be described below. The manufacturing method of the present invention preferably comprises the following steps 1 and 2. Step 1: A step to obtain a salicylate of formula (3) by reacting a triflate salt of formula (1) with a salicylic acid derivative of formula (2). Step 2: A step to obtain a halogen salt of formula (4) by reacting the salicylate of formula (3) obtained in step 1 with a hydrogen halide.

[0043] <Procedure for Step 1> Step 1 is a step of reacting the triflate salt of formula (1) with the salicylic acid derivative of formula (2) to obtain the salicylate of formula (3). The reaction in Step 1 is preferably carried out in a two-layer solvent system of an organic solvent that is immiscible with water, such as methylene chloride, 1,2-dichloroethane, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, methyl isobutyl ketone, methyl ethyl ketone, and propionitrile, or a mixed solvent obtained by mixing two or more of these, and water.

[0044] The procedure for carrying out step 1 using the above two-layer solvent system is described below. An alkaline aqueous solution capable of neutralizing the salicylic acid derivative of formula (2) is prepared as the aqueous phase. On the other hand, as the organic phase, the triflate salt of formula (1) and the salicylic acid derivative of formula (2) are dissolved in an organic solvent that is immiscible with water and capable of dissolving the triflate salt of formula (1) and the salicylic acid derivative of formula (2). After mixing this solution with the alkaline aqueous solution, an anion exchange reaction is carried out at a temperature of preferably 20 to 30°C (more preferably 20 to 25°C) for 5 to 60 minutes while stirring. The alkali used when preparing the alkaline aqueous solution is preferably an alkali metal bicarbonate, alkali metal carbonate, or alkali metal hydroxide, for example, sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, and cesium hydroxide. Generally, the amount of alkali used is 0.9 to 5 times the number of moles of the salicylic acid derivative of formula (2), with 1 to 2 times being preferred.

[0045] In the above reaction, the acid group of the salicylic acid derivative of formula (2) is neutralized by alkali to form a salt, and anion exchange with the triflate salt of formula (1) produces the salicylate of formula (3) and the alkali metal salt of triflate. At this time, the salicylate of formula (3) tends to migrate to the organic layer, while the alkali metal salt of triflate tends to migrate to the aqueous layer. During the reaction in step 1, it is presumed that the alkali metal salt of the salicylic acid derivative of formula (2) (especially the compound represented by formula (2-1) or formula (2-2) above) tends to be retained in the organic layer for a while due to the structure of the salicylic acid derivative of formula (2). As a result, the anion exchange reaction proceeds appropriately, and it is thought that the purity and yield of the halogen salt of formula (4) in the product obtained via step 2 tend to improve. On the other hand, when 2,6-dihydroxybenzoic acid or unsubstituted salicylic acid is used, it is presumed that the alkali metal salts of these compounds migrate to the aqueous layer quickly, resulting in low anion exchange efficiency.

[0046] After the above reaction, it is preferable to remove the aqueous layer and further wash the organic phase with the above-mentioned alkaline aqueous solution. Alternatively, after washing the organic phase with the alkaline aqueous solution, it is preferable to repeatedly stir and wash it with deionized water to remove the alkali metal salt of the salicylic acid derivative of formula (2) and the alkali metal salt of triflate contained in the organic phase.

[0047] In the reaction of step 1, the ratio of the triflate salt of formula (1) to the salicylic acid derivative of formula (2) is preferably 1 / 1 to 1 / 2 in molar ratio.

[0048] <Procedure for Step 2> Step 2 is a step in which the salicylate of formula (3) obtained in Step 1 is reacted with a hydrogen halide to obtain a halogen salt of formula (4). The reaction in Step 2 is preferably carried out in a two-layer solvent system consisting of an organic solvent that is immiscible with water and water. Examples of organic solvents that are immiscible with water include methylene chloride, 1,2-dichloroethane, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, methyl isobutyl ketone, methyl ethyl ketone, and propionitrile, as well as mixed solvents obtained by mixing two or more of these. Examples of hydrogen halides (halo acids) include hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide, with hydrogen chloride and hydrogen bromide being more preferred.

[0049] Step 2 is preferably a step in which an anion exchange reaction is carried out by adding an aqueous solution containing a halogen acid to the organic phase containing the salicylate of formula (3) obtained in Step 1, and stirring for 5 to 60 minutes at a temperature of preferably 20 to 30°C (more preferably 20 to 25°C). In the reaction of Step 2, the ratio of the salicylate of formula (3) to the halogen acid is preferably 1 / 1 to 1 / 5 in molar ratio.

[0050] In the above reaction, anions derived from the salicylic acid derivative of formula (2) in the salicylate of formula (3) exchange with halide ions to produce the halogen salt of formula (4). The halogen salt of formula (4) tends to migrate to the aqueous layer, while the anions derived from the salicylic acid derivative of formula (2) dissociated from the salicylate of formula (3) combine with protons to become nonionic and tend to migrate to the organic layer. The migration of the anions derived from the salicylic acid derivative of formula (2) to the organic layer rather than the aqueous layer containing the halogen salt of formula (4) tends to improve the purity and yield of the halogen salt of formula (4) in the product obtained through step 2. Furthermore, in the reaction of step 2, it is also preferable to add a good solvent for the halogen salt of formula (4) (for example, a lower alcohol solvent (preferably methanol)) to the system to facilitate the migration of the halogen salt of formula (4) produced in step 2 to the aqueous layer. Furthermore, in order to suppress the migration of the halogen salt of formula (4) into the organic layer, it is also preferable to add a poor solvent for the halogen salt of formula (4) (for example, an alkane having 6 or more carbon atoms, preferably an alkane having 6 to 8 carbon atoms, more preferably heptane) to the system.

[0051] After the above reaction, the aqueous layer and the organic layer are separated to obtain the aqueous phase. Furthermore, it is preferable to add an aqueous solution containing a halogen acid and a good solvent for the halogen salt of formula (4) (for example, a lower alcohol solvent (preferably methanol)) to the separated organic phase and repeatedly carry out the anion exchange reaction of the salicylate of formula (3) remaining in the organic layer and the liquid-liquid extraction treatment of the halogen salt of formula (4) remaining in the organic layer into the aqueous layer.

[0052] After the above reaction, it is also preferable to further reduce the amount of salicylic acid derivative of formula (2) remaining in the aqueous phase by adding an organic solvent with excellent solubility for the salicylic acid derivative of formula (2) (for example, an ether solvent and an alkane having 6 or more carbon atoms. For the ether solvent, an ether solvent having 4 to 10 carbon atoms is preferred, and diisopropyl ether and tert-butyl methyl ether are more preferred. For the alkane having 6 or more carbon atoms, an alkane having 6 to 8 carbon atoms is preferred, and heptane is more preferred) to the obtained aqueous phase, stirring, and repeating a washing treatment to remove the organic phase after stirring.

[0053] By concentrating the solution obtained by the above process under reduced pressure, a halogen salt represented by formula (4) can be obtained. The post-reaction treatment after steps 1 and 2 may be carried out in accordance with post-reaction methods commonly used in this field.

[0054] The present invention will be described in more detail below based on the following examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples.

[0055] [Example 1] Dissolve 1 g of tris(3,4-difluorophenyl)sulfonium triflate and 0.59 g of 4-(trifluoromethyl)salicylic acid in 18 mL of dichloromethane, add 5.8 mL of 5% sodium bicarbonate aqueous solution, stir at room temperature for 10 minutes, and remove the aqueous layer. Wash once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. Add 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane to the organic layer, stir at room temperature for 5 minutes, then separate the liquids and store the aqueous layer. Add 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid to the remaining organic layer and extract, mix the extracted aqueous layer with the stored aqueous layer, and discard the organic layer. Wash the mixed aqueous layer twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 2 mL of heptane, and add 365 mg of p-toluenesulfonic acid monohydrate as an internal standard to the aqueous layer. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of tris(3,4-difluorophenyl)sulfonium chloride (Cl), tris(3,4-difluorophenyl)sulfonium triflate (TfO), and 4-(trifluoromethyl)salicylic acid were as shown in Table 1. 4-(trifluoromethyl)salicylic acid was not detected. The calculated yield of tris(3,4-difluorophenyl)sulfonium chloride was 83%.

[0056] [Example 2] Dissolve 1 g of tris(3,4-difluorophenyl)sulfonium triflate and 0.72 g of 3,5-di-tert-butylsalicylic acid in 18 mL of dichloromethane, add 5.8 mL of 5% sodium bicarbonate aqueous solution, stir at room temperature for 10 minutes, and remove the aqueous layer. Wash once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. Add 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane to the organic layer, stir at room temperature for 5 minutes, then separate the liquids and store the aqueous layer. Add 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid to the remaining organic layer and extract, mix the extracted aqueous layer with the stored aqueous layer, and discard the organic layer. Wash the mixed aqueous layer twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 2 mL of heptane, and add 365 mg of p-toluenesulfonic acid monohydrate as an internal standard to the aqueous layer. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of tris(3,4-difluorophenyl)sulfonium chloride (Cl), tris(3,4-difluorophenyl)sulfonium triflate (TfO), and 3,5-di-tert-butylsalicylic acid are shown in Table 1. Tris(3,4-difluorophenyl)sulfonium triflate (TfO) and 3,5-di-tert-butylsalicylic acid were not detected. The calculated yield of tris(3,4-difluorophenyl)sulfonium chloride was 93%.

[0057] [Example 3] Dissolve 1 g of tris(3,4-difluorophenyl)sulfonium triflate and 0.70 g of 3,5,6-trichlorosalicylic acid in 18 mL of dichloromethane, add 5.8 mL of 5% sodium bicarbonate aqueous solution, stir at room temperature for 10 minutes, and remove the aqueous layer. Wash once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. Add 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane to the organic layer, stir at room temperature for 5 minutes, then separate the liquids and store the aqueous layer. Add 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid to the remaining organic layer and extract, mix the extracted aqueous layer with the stored aqueous layer, and discard the organic layer. Wash the mixed aqueous layer twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 2 mL of heptane, and add 365 mg of p-toluenesulfonic acid monohydrate as an internal standard to the aqueous layer. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of tris(3,4-difluorophenyl)sulfonium chloride (Cl), tris(3,4-difluorophenyl)sulfonium triflate (TfO), and 3,5,6-trichlorosalicylic acid were as shown in Table 1. 3,5,6-trichlorosalicylic acid was not detected. The calculated yield of tris(3,4-difluorophenyl)sulfonium chloride was 85%.

[0058] [Example 4] Dissolve 1 g of tris(3,4-difluorophenyl)sulfonium triflate and 0.85 g of 3,5-dibromosalicylic acid in 18 mL of dichloromethane, add 5.8 mL of 5% sodium bicarbonate aqueous solution, stir at room temperature for 10 minutes, and remove the aqueous layer. Wash once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. Add 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane to the organic layer, stir at room temperature for 5 minutes, then separate the liquids and store the aqueous layer. Add 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid to the remaining organic layer and extract, mix the extracted aqueous layer with the stored aqueous layer, and discard the organic layer. Wash the mixed aqueous layer twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 2 mL of heptane, and add 365 mg of p-toluenesulfonic acid monohydrate as an internal standard to the aqueous layer. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of tris(3,4-difluorophenyl)sulfonium chloride (Cl), tris(3,4-difluorophenyl)sulfonium triflate (TfO), and 3,5-dibromosalicylic acid are shown in Table 2. Tris(3,4-difluorophenyl)sulfonium triflate (TfO) and 3,5-dibromosalicylic acid were not detected. The calculated yield of tris(3,4-difluorophenyl)sulfonium chloride was 87%.

[0059] [Comparative Example 1] 1 g of tris(3,4-difluorophenyl)sulfonium triflate and 0.40 g of salicylic acid were dissolved in 18 mL of dichloromethane, and 5.8 mL of 5% sodium bicarbonate aqueous solution was added. The mixture was stirred at room temperature for 10 minutes, and the aqueous layer was removed. The mixture was washed once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane were added to the organic layer and stirred at room temperature for 5 minutes. The mixture was then separated, and the aqueous layer was stored. 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid were added to the remaining organic layer for extraction. The extracted aqueous layer was mixed with the stored aqueous layer, and the organic layer was discarded. The mixed aqueous layer was washed twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 2 mL of heptane. 365 mg of p-toluenesulfonic acid monohydrate was added to the aqueous layer as an internal standard. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of tris(3,4-difluorophenyl)sulfonium chloride (Cl), tris(3,4-difluorophenyl)sulfonium triflate (TfO), and salicylic acid were as shown in Table 2. The calculated yield of tris(3,4-difluorophenyl)sulfonium chloride was 52%.

[0060] [Comparative Example 2] 1 g of tris(3,4-difluorophenyl)sulfonium triflate and 0.44 g of 6-hydroxysalicylic acid were dissolved in 18 mL of dichloromethane, and 5.8 mL of 5% sodium bicarbonate aqueous solution was added. The mixture was stirred at room temperature for 10 minutes, and the aqueous layer was removed. The mixture was washed once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane were added to the organic layer and stirred at room temperature for 5 minutes. The mixture was then separated, and the aqueous layer was stored. 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid were added to the remaining organic layer for extraction. The extracted aqueous layer was mixed with the stored aqueous layer, and the organic layer was discarded. The mixed aqueous layer was washed twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 2 mL of heptane. 365 mg of p-toluenesulfonic acid monohydrate was added to the aqueous layer as an internal standard. １ 1H NMR and １９Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of tris(3,4-difluorophenyl)sulfonium chloride (Cl), tris(3,4-difluorophenyl)sulfonium triflate (TfO), and 6-hydroxysalicylic acid were as shown in Table 2. The calculated yield of tris(3,4-difluorophenyl)sulfonium chloride was 71%.

[0061] [Example 5] Dissolve 1 g of tris(4-fluorophenyl)sulfonium triflate and 0.81 g of 3,5-di-tert-butylsalicylic acid in 18 mL of dichloromethane, add 6.4 mL of 5% sodium bicarbonate aqueous solution, stir at room temperature for 10 minutes, and remove the aqueous layer. Wash once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. Add 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane to the organic layer, stir at room temperature for 5 minutes, then separate the liquids and store the aqueous layer. Add 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid to the remaining organic layer and extract, mix the extracted aqueous layer with the stored aqueous layer, and discard the organic layer. Wash the mixed aqueous layer twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 2 mL of heptane, and add 408 mg of p-toluenesulfonic acid monohydrate as an internal standard to the aqueous layer. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of tris(4-fluorophenyl)sulfonium chloride (Cl), tris(4-fluorophenyl)sulfonium triflate (TfO), and 3,5-di-tert-butylsalicylic acid are shown in Table 3. 3,5-di-tert-butylsalicylic acid was not detected. The calculated yield of tris(4-fluorophenyl)sulfonium chloride was 93%.

[0062] [Example 6] 1 g of bis(3,4-difluorophenyl)(4-fluorophenyl)sulfonium triflate and 0.75 g of 3,5-di-tert-butylsalicylic acid were dissolved in 18 mL of dichloromethane, and 6.0 mL of 5% sodium bicarbonate aqueous solution was added. The mixture was stirred at room temperature for 10 minutes, and the aqueous layer was removed. The mixture was washed once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane were added to the organic layer and stirred at room temperature for 5 minutes. The mixture was then separated, and the aqueous layer was stored. 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid were added to the remaining organic layer for extraction. The extracted aqueous layer was mixed with the stored aqueous layer, and the organic layer was discarded. The mixed aqueous layer was washed twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 2 mL of heptane. 379 mg of p-toluenesulfonic acid monohydrate was added to the aqueous layer as an internal standard. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of bis(3,4-difluorophenyl)(4-fluorophenyl)sulfonium chloride (Cl), bis(3,4-difluorophenyl)(4-fluorophenyl)sulfonium triflate (TfO), and 3,5-di-tert-butylsalicylic acid are shown in Table 3. Bis(3,4-difluorophenyl)(4-fluorophenyl)sulfonium triflate (TfO) and 3,5-di-tert-butylsalicylic acid were not detected. The calculated yield of bis(3,4-difluorophenyl)(4-fluorophenyl)sulfonium chloride was 90%.

[0063] [Example 7] 1 g of bis(4-fluorophenyl)(4-iodophenyl)sulfonium triflate and 0.78 g of 3,5-di-tert-butylsalicylic acid were dissolved in 18 mL of dichloromethane, and 5.8 mL of 5% sodium bicarbonate aqueous solution was added. The mixture was stirred at room temperature for 10 minutes, and the aqueous layer was removed. The mixture was washed once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane were added to the organic layer and stirred at room temperature for 5 minutes. The mixture was then separated, and the aqueous layer was stored. 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid were added to the remaining organic layer for extraction. The extracted aqueous layer was mixed with the stored aqueous layer, and the organic layer was discarded. The mixed aqueous layer was washed twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 3 mL of heptane. 331 mg of p-toluenesulfonic acid monohydrate was added to the aqueous layer as an internal standard. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of bis(4-fluorophenyl)(4-iodophenyl)sulfonium chloride (Cl), bis(4-fluorophenyl)(4-iodophenyl)sulfonium triflate (TfO), and 3,5-di-tert-butylsalicylic acid are shown in Table 3. Bis(4-fluorophenyl)(4-iodophenyl)sulfonium triflate (TfO) and 3,5-di-tert-butylsalicylic acid were not detected. The calculated yield of bis(4-fluorophenyl)(4-iodophenyl)sulfonium chloride was 83%.

[0064] [Example 8] 1 g of (4-iodophenyl)diphenylsulfonium triflate and 0.70 g of 3,5-di-tert-butylsalicylic acid were dissolved in 18 mL of dichloromethane, and 5.6 mL of 5% sodium bicarbonate aqueous solution was added. The mixture was stirred at room temperature for 10 minutes, and the aqueous layer was removed. The mixture was washed once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 18 mL of heptane were added to the organic layer. The mixture was stirred at room temperature for 5 minutes, and then the liquid-liquid was separated. The aqueous layer was stored. 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid were added to the remaining organic layer for extraction. The extracted aqueous layer was mixed with the stored aqueous layer, and the organic layer was discarded. The mixed aqueous layer was washed twice with a mixed solvent of 6 mL of tert-butyl methyl ether and 2 mL of heptane, and 353 mg of p-toluenesulfonic acid monohydrate and 664 mg of tris(4-fluorophenyl)sulfonium bromide were added to the aqueous layer as internal standards. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of (4-iodophenyl)diphenylsulfonium chloride (Cl), (4-iodophenyl)diphenylsulfonium triflate (TfO), and 3,5-di-tert-butylsalicylic acid are shown in Table 4. 3,5-di-tert-butylsalicylic acid was not detected. The calculated yield of (4-iodophenyl)diphenylsulfonium chloride was 90%.

[0065] [Example 9] 1 g of (4-fluorophenyl)bis(4-(trifluoromethyl)phenyl)sulfonium triflate and 0.66 g of 3,5-di-tert-butylsalicylic acid were dissolved in 18 mL of dichloromethane, 5.3 mL of 5% sodium bicarbonate aqueous solution was added, and the mixture was stirred at room temperature for 10 minutes. The aqueous layer was then removed. The mixture was washed once with 4 mL of 5% sodium bicarbonate aqueous solution and four times with 4 mL of deionized water. 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 36 mL of heptane were added to the organic layer and stirred at room temperature for 5 minutes. The mixture was then separated, and the aqueous layer was stored. 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid were added to the remaining organic layer for extraction. The extracted aqueous layer was mixed with the stored aqueous layer, and the organic layer was discarded. The mixed aqueous layer was washed twice with a mixed solvent of 4 mL of tert-butyl methyl ether and 4 mL of heptane. 336 mg of p-toluenesulfonic acid monohydrate was added to the aqueous layer as an internal standard. １ 1H NMR and １９ Analysis by 1F NMR revealed that the molar ratios (mol%) of each component relative to the total amount of (4-fluorophenyl)bis(4-(trifluoromethyl)phenyl)sulfonium chloride (Cl), (4-fluorophenyl)bis(4-(trifluoromethyl)phenyl)sulfonium triflate (TfO), and 3,5-di-tert-butylsalicylic acid are shown in Table 4. (4-fluorophenyl)bis(4-(trifluoromethyl)phenyl)sulfonium triflate (TfO) and 3,5-di-tert-butylsalicylic acid were not detected. The calculated yield of (4-fluorophenyl)bis(4-(trifluoromethyl)phenyl)sulfonium chloride was 89%.

[0066] [Example 10] 1 g of tris(4-(trifluoromethyl)phenyl)sulfonium triflate and 0.61 g of 3,5-di-tert-butylsalicylic acid were dissolved in 18 mL of dichloromethane. 4.9 mL of a 5% aqueous sodium hydrogen carbonate solution was added, and the mixture was stirred at room temperature for 10 minutes. Then, the aqueous layer was removed. The organic layer was washed once with 4 mL of a 5% aqueous sodium hydrogen carbonate solution and four times with 4 mL of ion-exchanged water. 6 mL of methanol, 6 mL of 1 mol / L hydrochloric acid, and 54 mL of heptane were added to the organic layer, and the mixture was stirred at room temperature for 5 minutes and then separated. The aqueous layer was stored. 6 mL of methanol and 6 mL of 1 mol / L hydrochloric acid were added to the remaining organic layer for extraction. The aqueous layer obtained by extraction was mixed with the stored aqueous layer, and the organic layer was discarded. The mixed aqueous layer was washed twice with a mixed solvent of 4 mL of tert-butyl methyl ether and 6 mL of heptane. 309 mg of p-toluenesulfonic acid monohydrate was added to the aqueous layer as an internal standard and １ 1H NMR and １９ 19F NMR analysis showed that the molar conversion ratios (mol%) of each component with respect to the total amount of tris(4-(trifluoromethyl)phenyl)sulfonium chloride (Cl form), tris(4-(trifluoromethyl)phenyl)sulfonium triflate (TfO form), and 3,5-di-tert-butylsalicylic acid were as shown in the results of Table 4. Note that tris(4-(trifluoromethyl)phenyl)sulfonium triflate (TfO form) and 3,5-di-tert-butylsalicylic acid were not detected. The calculated yield of tris(4-(trifluoromethyl)phenyl)sulfonium chloride was 97%.

[0067] Tables 1 to 4 are shown below. As described above, in this specification, the "purity of the halogen salt of formula (4) in the product" means the molar conversion content (mol%) of each component with respect to the total amount of the halogen salt of formula (4) as the target product, the triflate salt of formula (1), and the salicylic acid derivative of formula (2) as raw material components in the product, which is represented by the molar conversion content of the halogen salt of formula (4). That is, the "purity of the halogen salt of formula (4) in the product" and the "purity of the comparative halogen salt in the product" in each example and comparative example are represented by the numerical values described in the "Cl form" column in the "molar conversion ratio (mol%)" column in Tables 1 to 4.

[0068]

[0069]

[0070]

[0071]

[0072] The results from the examples clearly show that the product obtained by the manufacturing method of the present invention has a high purity of the halogen salt of formula (4) and a significant reduction in the amount of triflate salt of formula (1) remaining in the product. Furthermore, it is clear that the manufacturing method of the present invention also yields excellent yield of the halogen salt of formula (4).

Claims

1. A method for producing a triarylsulfonium compound, comprising reacting a compound represented by formula (1) with a compound represented by formula (2) to obtain a compound represented by formula (3), and then reacting the compound represented by formula (3) with hydrogen halide to obtain a compound represented by formula (4). In the formula, R １ to R １５ each independently represents a hydrogen atom or an electron-withdrawing group. However, at least one of R １ to R １５ represents an electron-withdrawing group. In the formula, R １６ represents a halogen atom, an alkyl group having 1 to 10 carbon atoms, or a fluoroalkyl group having 1 to 10 carbon atoms. n represents an integer of 1 to 4. When n represents an integer of 2 or more, a plurality of R １６ may be the same as or different from each other. Also, two adjacent R １６ may be bonded to each other to form an aromatic ring. In the formula, R １ to R １５ each independently represents a hydrogen atom or an electron-withdrawing group. However, at least one of R １ to R １５ represents an electron-withdrawing group. R １６ represents a halogen atom, an alkyl group having 1 to 10 carbon atoms, or a fluoroalkyl group having 1 to 10 carbon atoms. n represents an integer of 1 to 4. When n represents an integer of 2 or more, a plurality of R １６ may be the same as or different from each other. Also, two adjacent R １６ may be bonded to each other to form an aromatic ring. In the formula, R １ to R １５ each independently represents a hydrogen atom or an electron-withdrawing group. However, at least one of R １ to R １５ represents an electron-withdrawing group. X － represents a halide ion.

2. The aforementioned R １６ However, n represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms, or n represents an integer of 2 or more, and two adjacent R １６ A method for producing a triarylsulfonium compound according to claim 1, wherein the compounds bond with each other to form an aromatic ring.

3. The aforementioned R １６ However, n represents a chlorine atom, a bromine atom, an alkyl group having 1 to 6 carbon atoms, or a perfluoroalkyl group having 1 to 3 carbon atoms, or n represents an integer of 2 or more, and two adjacent R １６ A method for producing a triarylsulfonium compound according to claim 1, wherein the compounds bond with each other to form an aromatic ring.

4. The aforementioned R １６ A method for producing a triarylsulfonium compound according to claim 1, wherein the triarylsulfonium compound represents a chlorine atom, a bromine atom, a C1-C6 alkyl group, or a C1-C3 perfluoroalkyl group.

5. The method for producing a triarylsulfonium compound according to claim 1, wherein the compound represented by formula (2) is selected from the group consisting of the compound represented by formula (2-1), the compound represented by formula (2-2), the compound represented by formula (2-3), the compound represented by formula (2-4), and the compound represented by formula (2-5).

6. The method for producing a triarylsulfonium compound according to claim 5, wherein the compound represented by formula (2) is selected from the group consisting of the compound represented by formula (2-1) and the compound represented by formula (2-2).

7. A method for producing a triarylsulfonium compound according to any one of claims 1 to 6, wherein the ratio of the amount of compound represented by formula (1) to the amount of compound represented by formula (2) is 1 / 1 to 1 / 2 in molar ratio.

8. A method for producing a triarylsulfonium compound according to any one of claims 1 to 6, wherein the electron-withdrawing group is selected from the group consisting of a halogen atom, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 2 to 11 carbon atoms, an alkylsulfonyl group having 1 to 10 carbon atoms, a nitrile group, and an alkoxysulfonyl group having 1 to 10 carbon atoms.

9. The aforementioned X － A method for producing a triarylsulfonium compound according to any one of claims 1 to 6, wherein the compound represents a chloride ion or a bromide ion.

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