Method for purifying aromatic thiol compounds

Abstract

To provide a method for easily or efficiently purifying aromatic thiol compounds which easily form a multimer by oxidation (or disulfidation) compared to ordinary thiol compounds (or a method for easily or efficiently producing high-purity aromatic thiol compounds).SOLUTION: Aromatic thiol compounds are purified by a process, comprising: a base mixing step of mixing aromatic thiol compounds having at least one mercapto group substituted on the aromatic ring, a basic component, and an aqueous solvent; a separation step of removing insoluble matter from a mixture obtained in the base mixing step; and an acid mixing step of mixing an acid component with a solution obtained in the separation step.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for purifying aromatic thiol compounds substituted with mercapto groups (thiol groups) [especially naphthalenthol compounds in which at least one substitution position selected from the 1-8 positions of the naphthalene ring (or naphthalene skeleton) is substituted with a mercapto group (thiol group)] (or a method for producing highly pure aromatic thiol compounds such as naphthalenthol compounds). [Background technology]

[0002] Aromatic thiol compounds, particularly naphthalenchiol compounds or their derivatives, are used in various fields such as optical materials, electrical and electronic materials, and pharmaceuticals, as functional materials, raw materials, or reaction intermediates.

[0003] Japanese Patent Publication No. 2008-527413 (Patent Document 1) discloses a display comprising a translucent substrate and a predetermined hard coat layer bonded to the substrate. Example 12 of this document describes reacting 2,7-dihydroxynaphthalene with dimethylthiocarbamoyl chloride to produce dimethyl-thiocarbamate O-(7-dimethylthiocarbamoyloxy-naphthalen-2-yl) ester, drying and heating the resulting mixture, cooling, and recrystallizing the solid from ethyl acetate to obtain dimethyl-thiocarbamate S-(7-dimethylcarbamoylsulfanyl-naphthalen-2-yl) ester. The obtained compound is then added to an aqueous mixture of ethanol and potassium solution, heated under reflux, cooled, diluted with water, acidified with hydrochloric acid, and the solid is filtered and dried to obtain 2,7-naphthalenedithiol.

[0004] Furthermore, Japanese Patent Publication No. 2005-179289 (Patent Document 2) discloses 6-alkoxy-2-naphthalenchiol as a novel thiol compound in which a -SH group (mercapto group or thiol group) is directly introduced into a naphthalene skeleton, which is highly useful as a raw material for sulfonium salts and other sulfur-containing compounds that can be expected to be photoacid generators. Example 3 of this document describes that 6-n-butyloxynaphthalene-2-sulfonyl chloride was reduced by adding zinc powder as a reducing agent and hydrochloric acid to a toluene solution, then the unreacted zinc was removed, the organic layer was washed with pure water, and the toluene was removed to bring it to a dry state, and then it was completely dissolved in n-heptane at 50°C, cooled to 10°C and crystallized, and the filtered wet material was dried under reduced pressure to prepare 6-n-butyloxy-2-naphthalenchiol.

[0005] Furthermore, the following publications, edited by the Chemical Society of Japan and published by Maruzen Co., Ltd., "Experimental Chemistry Course 24, 4th Edition: Organic Synthesis VI - Heteroatom and Main Group Metal Compounds," 2nd printing, October 30, 1994 (Non-Patent Literature 1), and Shigeru Ohya, "Reactions of Mercaptans," Journal of the Society of Synthetic Organic Chemistry, 1968, Vol. 26, No. 4, pp. 327-341 (Non-Patent Literature 2), describe the formation of disulfide compounds by oxidation of thiol compounds (or their susceptibility to oxidation). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-527413 (Claim 1 and 6,

[0031] ,

[0038] , Example 12) [Patent Document 2] Japanese Patent Publication No. 2005-179289 (Claim 1 and 4, Example 3) [Non-patent literature]

[0007] [Non-Patent Document 1] Edited by: The Chemical Society of Japan; Published by: Maruzen Co., Ltd.; "Experimental Chemistry Course 24, 4th Edition: Organic Synthesis VI - Heteroatom and Main Group Metal Compounds," 2nd printing, October 30, 1994 (page 330, b. Disulfides (i)) [Non-Patent Document 2] Shigeru Ohya, "Reactions of Mercaptans," Journal of Synthetic Organic Chemistry, 1968, Vol. 26, No. 4, pp. 327-341 (p. 336 V. Oxidation to Disulfide) [Overview of the project] [Problems that the invention aims to solve]

[0008] In Example 12 of Patent Document 1, 2,7-naphthalenedithiol is prepared as a reaction intermediate for the final product, 2,7-bis(2-acryloyloxyethylthio)naphthalene, through a multi-step reaction process. For this reason, it is described that the 2,7-naphthalenedithiol obtained by filtration and drying was not particularly purified, but was subjected to the reaction with ethylene carbonate in the next step.

[0009] Furthermore, in Example 3 of Patent Document 2, it is described that 6-n-butyloxy-2-naphthalenchiol produced by a reduction reaction was purified by crystallization in n-heptane.

[0010] However, thiol compounds readily oxidize in air and other environments, causing the mercapto group to disulfide and readily forming polymers (disulfide compounds) such as dimers. Furthermore, because these polymers (especially dimers) may exhibit a similar level of crystallinity (or solubility in organic solvents) as the original thiol compound, even purification by crystallization can be difficult, making it challenging to separate the thiol compound from impurities such as its polymers, and thus preventing sufficient purity from being achieved. Moreover, the yield tends to decrease as the amount of impurities is reduced, and since high purity and high yield are usually in a trade-off relationship, it has been extremely difficult to easily or efficiently produce even higher purity thiol compounds in high yield.

[0011] Non-patent document 1 states that the ease with which thiol compounds are oxidized (ease of forming disulfide compounds) is in the order of benzenethiol > primary thiol > secondary thiol > tertiary thiol, and that oxidation proceeds even with oxygen in the air and is accelerated under alkaline conditions (page 330, b. Disulfide (i)).

[0012] Furthermore, Non-Patent Literature 2 also describes various factors in the oxidation of thiol compounds (mercaptans) (pages 336-339, V. Oxidation to Disulfide). For example, in page 336-337, section V.1. Air Oxidation, it is disclosed that thiol compounds are oxidized by oxygen at low temperatures to form disulfides, regardless of the presence or absence of a catalyst. That is, a thiolate (thiolate ion or thiolate anion) is first generated by the dissociation of the thiol compound, this thiolate undergoes electron transfer with oxygen to generate a thiyl radical, and this thiyl radical is dimerized to generate a disulfide. It is also described that, due to this reaction pathway, the reaction proceeds quickly in the presence of an alkali, alkylamines act as catalysts in the same way as alkalis, and the reactivity of the electron transfer between the thiolate ion and oxygen, which is the rate-determining step of the reaction, is generally ArSH > HO2CCH2SH > RCH2SH > R2CHSH > R3CSH.

[0013] Furthermore, Non-Patent Literature 2 describes that, in addition to air oxidation, thiol compounds can be oxidized by iron salts such as ferric octanoate to form disulfides, and in this reaction, aryl mercaptans react an order of magnitude faster than aliphatic mercaptans (page 338, V.2. Oxidation by Metal Oxides, etc.); disulfides are also formed in reactions with sulfoxides such as tetramethylene sulfoxide and phenylmethyl sulfoxide, and in the reaction with the former, the reactivity (ease of oxidation) decreases in the order of benzenethiol > 2-methylbenzenethiol > α-toluenethiol > 1-dodecanethiol, and they are catalyzed by amines; and in the reaction with the latter, the ease of oxidation decreases in the order of ArSH > RCH2SH > RR'R''CSH (pages 338-339, V.3. Oxidation by Sulfoxides and N-Oxides).

[0014] Thus, in thiol compounds (aromatic thiol compounds or thiophenol compounds) in which a mercapto group is directly bonded to an aromatic ring such as a benzene ring, oxidation is more easily performed (or the mercapto group is more active) compared to primary to tertiary thiol compounds, making it particularly difficult to suppress the inclusion of polymers such as dimers that are formed.

[0015] Therefore, the object of the present invention is to provide a method for easily or efficiently purifying aromatic thiol compounds such as naphthalenchiol compounds, which tend to form polymers by oxidation (or disulfideation) compared to ordinary thiol compounds (or a method for easily or efficiently producing highly pure aromatic thiol compounds such as naphthalenchiol compounds). [Means for solving the problem]

[0016] As a result of diligent research to achieve the above objectives, the present inventors discovered that purifying aromatic thiol compounds (thiol compounds in which a mercapto group is directly bonded to an aromatic ring such as a naphthalene ring) by a specific process, despite going through a process under basic (or alkaline) conditions that promote oxidation, surprisingly does not increase the polymer content, but rather reduces the amount of impurities, thus completing the present invention. That is, the present invention may include the following embodiments.

[0017] Embodiment [1]: A method for purifying an aromatic thiol compound in which at least one mercapto group is substituted on an aromatic ring, A base mixing step involves mixing the aromatic thiol compound, a base component, and an aqueous solvent. From the mixture obtained in this base mixing step, a separation step is performed to remove insoluble matter. A purification method comprising an acid mixing step of mixing an acid component with the solution obtained in the separation step.

[0018] Embodiment [2]: The purification method according to Embodiment [1], wherein the aqueous solvent comprises at least one selected from water and alcohol.

[0019] Embodiment [3]: The purification method according to Embodiment [1] or [2], wherein the proportion of the aqueous solvent is 100 to 3000 parts by mass per 100 parts by mass of the aromatic thiol compound.

[0020] Embodiment [4]: ​​The purification method according to any of Embodiments [1] to [3], wherein the base mixing step is performed in the presence of a reducing agent and / or a polymerization inhibitor (further mixing of the reducing agent and / or polymerization inhibitor).

[0021] Embodiment [5]: The purification method according to Embodiment [4], wherein the reducing agent and / or polymerization inhibitor comprises at least an alkali metal boron hydride.

[0022] Embodiment [6]: The purification method according to Embodiment [4] or [5], wherein the total amount of the reducing agent and polymerization inhibitor is 0.001 to 0.1 moles per mole of mercapto group of the aromatic thiol compound.

[0023] Embodiment [7]: The purification method according to any one of Embodiments [1] to [6], wherein the basic component comprises at least an alkali metal hydroxide.

[0024] Embodiment [8]: The purification method according to any one of Embodiments [1] to [7], wherein the proportion of the basic component is 1 to 2 moles per mole of mercapto group of the aromatic thiol compound.

[0025] Embodiment [9]: A purification method according to any one of Embodiments [1] to [8], wherein the mixture obtained in the base mixing step is heated to a temperature of 50°C or higher.

[0026] Embodiment

[10] : The purification method according to any one of Embodiments [1] to [9], wherein the base mixing step is performed under an inert gas atmosphere.

[0027] Embodiment

[11] : The purification method according to any of Embodiments [1] to

[10] , wherein the yield is 85 mol% or more.

[0028] Embodiment

[12] : The purification method according to any one of Embodiments [1] to

[11] , wherein the content of the aromatic thiol compound is 85% by mass or more in the crude product before purification and 95% by mass or more in the purified product after purification.

[0029] Embodiment

[13] : The aromatic thiol compound is C 6-14 A purification method according to any one of embodiments [1] to

[12] , wherein the thiol compound is in which at least one mercapto group is substituted on an aromatic hydrocarbon ring.

[0030] Embodiment

[14] : The purification method according to any one of Embodiments [1] to

[13] , wherein the aromatic thiol compound is a naphthalenthol compound having a mercapto group at any substitution position selected from the group consisting of the 1,6-, 2,6-, and 2,7-positions of the naphthalene ring.

[0031] Embodiment

[15] : A purification method according to any one of Embodiments [1] to

[14] for reducing the content of the polymer of the aromatic thiol compound. [Effects of the Invention]

[0032] In this invention, because purification is performed by a specific process, aromatic thiol compounds (e.g., naphthalenchiol compounds) that are more prone to forming polymers by oxidation (or disulfideation) than ordinary thiol compounds can be easily or efficiently purified [that is, high-purity aromatic thiol compounds (e.g., naphthalenchiol compounds) can be easily or efficiently (or in high yield)]. Moreover, despite going through a process under basic (or alkaline) conditions that further promote oxidation, the amount of impurities can be effectively reduced without significantly increasing the polymer content. [Modes for carrying out the invention]

[0033] The present invention provides a method for purifying aromatic thiol compounds (e.g., naphthalenthol compounds) [a method for reducing impurities or a method for producing highly pure aromatic thiol compounds (e.g., naphthalenthol compounds)], which includes at least a base mixing step, a separation step, and an acid mixing step.

[0034] [Base mixing process] In the base mixing step (or base formation step), an aromatic thiol compound (e.g., a naphthalenchiol compound) is mixed with a basic component (or alkaline component) and an aqueous solvent. In this step, the thiolate compound (where the mercapto group [-SH] is replaced with [-S]) corresponding to the aromatic thiol compound is formed. - A thiolate ion or thiolate anion is formed, and the resulting thiolate compound is dissolved or extracted into the aqueous solvent.

[0035] The aromatic thiol compound (crude raw material, crude product, or crude containing impurities before purification) is not particularly limited and may include aromatic thiol compounds described later (for example, naphthalenchiol compounds).

[0036] Examples of basic (or alkaline) components include inorganic bases [e.g., metal hydroxides (e.g., alkali metal hydroxides such as sodium hydroxide and potassium hydroxide)] and metal alkoxides [e.g., alkali metal C such as sodium methoxide, sodium ethoxide, and potassium t-butoxide]. 1-6 Examples include alkoxides, ammonia, etc., and organic bases [for example, amines (e.g., trialkylamines such as triethylamine, tris(hydroxyalkyl)amines such as triethanolamine, pyridine, morpholine, heterocyclic amines such as N-methylmorpholine, etc.)]. These basic components (or alkaline components) can be used alone or in combination of two or more. Among these basic components (or alkaline components), alkali metal hydroxides such as sodium hydroxide are preferred.

[0037] The proportion of the basic component (or alkaline component) [especially alkali metal hydroxides such as sodium hydroxide] may be, for example, about 1 to 3 moles per mole of mercapto groups of aromatic thiol compounds such as naphthalenchiol compounds (crude raw materials including impurities before purification, crude products, or crude), preferably about 1.05 to 2 moles, and more preferably about 1.1 to 1.5 moles.

[0038] Examples of aqueous solvents include water, alcohol (or polyol compounds). Examples of alcohols or polyol compounds include methanol, ethanol, n-propanol, isopropanol, butanol, etc. 1-6 Alcohols, (poly)alkylene glycols [e.g., (poly)C such as ethylene glycol, diethylene glycol, propylene glycol, etc.] 2-6 [such as alkylene glycols], (poly)alkylene glycol monoalkyl ethers [for example, (poly)C such as ethylene glycol monoethyl ether (or cellosolve), diethylene glycol monoethyl ether (or carbitol)]. 2-6 Alkylene glycol mono C 1-6Examples include alkyl ethers and glycerin. These aqueous solvents can be used individually or in combination of two or more. Of these aqueous solvents, water is preferred.

[0039] The proportion of the aqueous solvent (especially water) may be, for example, 70 to 99% by mass (e.g., 80 to 97% by mass), preferably 85 to 95% by mass (e.g., 87 to 93% by mass), relative to the total amount of the aqueous solvent and the basic component. Alternatively, the proportion of the aqueous solvent (especially water) may be, for example, 10 to 10,000 parts by mass (e.g., 50 to 5,000 parts by mass), preferably 100 to 3,000 parts by mass (e.g., 150 to 2,000 parts by mass), more preferably 200 to 1,000 parts by mass (e.g., 250 to 800 parts by mass), and particularly 300 to 600 parts by mass, relative to 100 parts by mass of the aromatic thiol compound such as the naphthalenchiol compound (crude raw material, crude product, or crude containing impurities before purification), preferably 100 to 3,000 parts by mass (e.g., 150 to 2,000 parts by mass), more preferably 200 to 1,000 parts by mass (e.g., 250 to 800 parts by mass), and especially preferably 300 to 600 parts by mass. If the proportion of aqueous solvent is too low, it may be difficult to sufficiently dissolve or extract the thiolate compound, potentially leading to a decrease in yield. Conversely, if the proportion of aqueous solvent is too high, impurities may also dissolve more easily, potentially preventing sufficient improvement in purity.

[0040] As described in Non-Patent Documents 1 and 2, aromatic thiol compounds in which a mercapto group is directly bonded to an aromatic ring (benzene ring) skeleton are more susceptible to oxidation even in the atmosphere (air) than ordinary primary to tertiary thiol compounds, possibly due to the higher activity of the mercapto group. In particular, the oxidation reaction tends to be accelerated under basic (or alkaline) conditions. Therefore, in the base mixing step, a reducing agent and / or polymerization inhibitor may be added to effectively suppress the disulfideation (polymerization) of the aromatic thiol compound.

[0041] Examples of reducing agents include metal hydrides (e.g., alkali metal boron hydrides such as lithium borohydride, sodium borohydride, lithium triethylborohydride, lithium tri(s-butyl)borohydride, sodium tri(s-butyl)borohydride, potassium tri(s-butyl)borohydride, sodium triacetoxyborohydride, sodium cyanoborohydride, etc., aluminum hydrides such as lithium aluminum hydride, sodium bis(2-methoxyethoxy)aluminum hydride, diisobutylaluminum hydride, etc., nickel borohydride, zinc borohydride, tributyltin hydride, etc.), borane complexes (e.g., borane-dimethyl sulfide complex, borane-tetrahydrofuran complex, etc.), silanes (e.g., triethylsilane), phosphines (e.g., tris(2-carboxyethyl)phosphine hydrochloride), and sulfites (e.g., sodium sulfite).

[0042] Examples of polymerization inhibitors (radical polymerization inhibitors) include quinones [e.g., hydroquinone (p-benzoquinone, etc.), t-butylhydroquinone, methoquinone (or p-methoxyphenol), tolquinone (or methyl-p-benzoquinone), 2,5-diphenyl-p-benzoquinone, etc.], catechols (t-butylcatechol, etc.), amines (diphenylamine, diphenylpicrylhydrazyl, etc.), and nitro compounds (nitrobenzene, etc.).

[0043] These reducing agents and / or polymerization inhibitors can be used individually or in combination of two or more. Of these reducing agents and / or polymerization inhibitors, metal hydrides (such as alkali metal boron hydrides like sodium borohydride) and quinones (such as hydroquinone and methoquinone) are preferred, and metal hydrides (such as alkali metal boron hydrides like sodium borohydride) are even more preferred as reducing agents.

[0044] The total ratio of the reducing agent and polymerization inhibitor (in particular, the ratio of alkali metal borohydride such as sodium borohydride as a reducing agent) may be, for example, about 0.001 to 0.1 moles (e.g., 0.005 to 0.08 moles) per mole of mercapto groups of the aromatic thiol compound such as the naphthalenchiol compound (crude raw material including impurities before purification, crude product, or crude), and preferably about 0.01 to 0.05 moles (e.g., 0.02 to 0.04 moles).

[0045] In the base mixing step, the resulting mixture may be heat-treated as needed. Heating effectively promotes the dissolution or extraction of the thiolate compound in the aqueous solvent, making it easier to improve the yield. The heating temperature may be, for example, 40°C or higher (e.g., 45-100°C), preferably 50°C or higher (e.g., 55-80°C), and more preferably 60-70°C. If the heating temperature is too high, disulfide formation (polymer formation) by oxidation of the aromatic thiol compound may be accelerated, making it difficult to improve purity.

[0046] The base mixing step may be carried out in an atmospheric environment (in air) or an inert gas atmosphere. From the viewpoint of effectively suppressing disulfide formation (polymer formation) due to oxidation of aromatic thiol compounds, it is preferable to carry out the step in an inert gas atmosphere (non-oxidizing gas atmosphere or in the absence of oxygen gas), such as nitrogen gas or a noble gas like argon gas.

[0047] [Separation process] In the separation step, insoluble substances or impurities that did not dissolve in the aqueous solvent [for example, reagents (e.g., catalysts) introduced during the preparation of aromatic thiol compounds, organic solvents, salts such as inorganic salts, metal components, or polymers of aromatic thiol compounds (e.g., dimers, trimers or more) generated during the preparation or storage] are separated or removed from the mixture obtained in the base mixing step, and the aqueous solvent solution portion is recovered.

[0048] The method of separation or removal is not particularly limited and includes conventional separation methods such as filtration, centrifugation, and decantation, with filtration being preferred.

[0049] The temperature during the separation process (separation operations such as filtration) may be, for example, around room temperature (e.g., 20-30°C), or it may be carried out while heating, with room temperature (e.g., 20-30°C) being preferable. When heating is used, the heating temperature may be in the same range as the range exemplified as the heating temperature in the base mixing process, including preferred embodiments. If the temperature is too high, the disulfide formation (polymer formation) due to oxidation of the aromatic thiol compound may be accelerated, making it difficult to improve purity.

[0050] The separated or removed insoluble matter (or residue) does not need to be washed, but it may be washed with an aqueous solvent, and the washing solution after washing may also be recovered. Examples of aqueous solvents used for washing include those similar to the aqueous solvents exemplified in the base mixing step, and can be used alone or in combination of two or more. Water is preferred as the aqueous solvent used for washing. The amount of aqueous solvent used for washing may be, for example, 10 to 3000 parts by mass (for example, 30 to 2000 parts by mass), preferably about 50 to 1600 parts by mass, per 100 parts by mass of aromatic thiol compounds such as naphthalenchiol compounds (crude raw materials including impurities before purification, crude products, or crude).

[0051] The separation process may be carried out under an atmospheric environment (in air) or an inert gas atmosphere. From the viewpoint of effectively suppressing disulfide formation (polymer formation) due to oxidation of aromatic thiol compounds, it is preferable to carry out the process under an inert gas atmosphere (non-oxidizing gas atmosphere or in the absence of oxygen gas), such as nitrogen gas or a noble gas like argon gas.

[0052] Furthermore, the solution obtained in the separation operation (the aqueous solvent solution portion) may be combined with the addition of activated carbon, stirring, and filtration. This operation (adsorption treatment with activated carbon) is effective when turbidity is observed in the solution obtained in the separation operation (the aqueous solvent solution portion).

[0053] [Acid mixing process] In the acid mixing step (or acid precipitation step), the acid component is mixed with the solution separated in the separation step (the aqueous solvent solution portion). By mixing the acid component, the thiolate form of the aromatic thiol compound is separated into [-S - The compound is returned to the mercapto group [-SH] state (thiol compound) and precipitated from an aqueous solvent.

[0054] The acid component is not particularly limited and may include, for example, inorganic acids (e.g., hydrogen chloride or hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.), organic acids [e.g., carboxylic acids such as acetic acid, propionic acid, oxalic acid; (halo)alkanesulfonic acids such as methanesulfonic acid and trifluoromethanesulfonic acid, sulfonic acids such as p-toluenesulfonic acid, etc.], and may also be solid acids.

[0055] Examples of solid acids include inorganic solid acids such as metal compounds (oxides, complex oxides, sulfides, sulfates, polyacids, etc.), nonmetallic sulfates, clay minerals, zeolites, and kaolin; and organic solid acids such as cation exchange resins [for example, strongly acidic cation exchange resins such as ion exchange resins having sulfonic acid groups, and weakly acidic cation exchange resins such as ion exchange resins having carboxylic acid groups (for example, (meth)acrylic acid-divinylbenzene copolymer, etc.)].

[0056] These acidic components can be used individually or in combination of two or more. Among these acidic components, inorganic acids such as hydrochloric acid are preferred. The concentration of hydrochloric acid may be, for example, 10 to 37% by mass, preferably 20 to 37% by mass, and more preferably around 30 to 37% by mass.

[0057] The acid component may be mixed until the solution becomes acidic (for example, with a pH of about 1 to 2). The specific proportion of the acid component (especially an inorganic acid such as hydrochloric acid) (or the proportion of protons that the acid component can donate) may be, for example, about 1 to 3 moles per mole of mercapto groups of an aromatic thiol compound such as a naphthalenchiol compound (crude raw material containing impurities before purification, crude product, or crude), preferably 1.1 to 2 moles, and more preferably about 1.2 to 1.7 moles (for example, about 1.3 to 1.5 moles).

[0058] The acid component may be added slowly over time (for example, 0.5 to 2 hours), or in multiple stages. Furthermore, the mixture may be stirred for 0.5 to 2 hours after the addition of the acid component.

[0059] The temperature during the acid mixing step may be, for example, around 0 to 70°C, preferably 10 to 50°C (e.g., 20 to 40°C), and especially room temperature (e.g., 20 to 30°C). If the temperature is too high, the disulfide formation (polymer formation) by oxidation of the aromatic thiol compound may be accelerated, making it difficult to improve purity.

[0060] The acid mixing step may be carried out in an atmospheric environment (in air) or an inert gas atmosphere. From the viewpoint of effectively suppressing disulfide formation (polymer formation) due to oxidation of aromatic thiol compounds, it is preferable to carry out the step in an inert gas atmosphere (non-oxidizing gas atmosphere or in the absence of oxygen gas), such as nitrogen gas or a noble gas like argon gas.

[0061] The purified aromatic thiol compound precipitated from the aqueous solvent in the acid mixing step may be separated from the aqueous solvent layer by conventional methods, such as filtration, centrifugation, or decantation. If the purified aromatic thiol compound is liquid at room temperature, it may also be separated by liquid-liquid separatory.

[0062] The purified aromatic thiol compound separated from the aqueous solvent layer may be recovered without washing, or it may be washed with an aqueous solvent. Examples of aqueous solvents used for washing include those similar to the aqueous solvents exemplified in the base mixing step, and can be used alone or in combination of two or more. Water is preferred as the aqueous solvent used for washing. Washing may be carried out until the pH of the solution after washing becomes neutral to remove acidic components. The specific amount of aqueous solvent (especially water) used for washing may be, for example, 1000 to 10000 g (e.g., 2000 to 8000 g), preferably about 3000 to 6000 g, per mole of aromatic thiol compounds such as naphthalenchiol compounds (crude raw materials including impurities before purification, crude products, or crude).

[0063] The purified aromatic thiol compound, separated from the aqueous solvent layer, may be subjected to drying (such as heating and / or vacuum drying).

[0064] In this way, by purifying the compound through a base mixing step, a separation step, and an acid mixing step, high-purity aromatic thiol compounds can be easily or efficiently produced in high yield.

[0065] Furthermore, the method of the present invention may include other steps different from the base mixing step, separation step, and acid mixing step described above. Examples of other purification steps include conventional purification operations, specifically washing, liquid-liquid extraction or extraction, concentration, neutralization, crystallization or precipitation, solid-liquid separation (filtration, centrifugation, etc.), column chromatography, adsorption treatment (treatment with porous materials such as activated carbon, etc.), drying or drying to dryness, distillation (vacuum distillation, etc.), or sublimation. These other steps may be performed individually or in combination of two or more. In these purification operations, impurities may not be sufficiently reduced, or even if they are, the yield may decrease, or the purification operation itself may not be applicable depending on the type of aromatic thiol compound or its positional isomer. However, the purification method of the present invention can produce highly purified aromatic thiol compounds in high yield without combining them with these purification operations.

[0066] [Aromatic thiol compound] (Structure and properties of aromatic thiol compounds, etc.) The aromatic thiol compound purified by the purification method of the present invention is not particularly limited as long as it is a compound in which at least one mercapto group (or thiol group) [-SH] is substituted (or directly bonded) on the aromatic ring, and the aromatic ring may have other substituents. Representative aromatic rings include, for example, aromatic hydrocarbon rings (arene rings), aromatic heterocyclic rings [for example, aromatic rings containing at least one hetero element (such as Group 15 and / or Group 16 elements of the periodic table) such as pyrrole rings, pyridine rings, furan rings, thiophene rings, etc.].

[0067] As a representative aromatic thiol compound, for example, a compound represented by the following formula (1) may be used.

[0068] [[ID=1十二]] [Chemical formula]

[0069] (In the formula, Ar represents an aromatic hydrocarbon ring (arene ring), [[ID=二十三]]n represents an integer of 1 or more, R 1 represents a substituent, and p represents an integer of 0 or more).

[0070] In the formula (1), the aromatic hydrocarbon ring (arene ring) Ar may be a monocyclic aromatic hydrocarbon ring such as a benzene ring, or a polycyclic aromatic hydrocarbon ring such as a condensed polycyclic or ring assembly.

[0071] Examples of the condensed polycyclic aromatic hydrocarbon ring include C such as naphthalene ring, anthracene ring, phenanthrene ring 10-14 Condensed polycyclic aromatic hydrocarbon rings and the like. Examples of the ring assembly aromatic hydrocarbon ring include biaryl rings such as biphenyl ring, binaphthyl ring, phenylnaphthalene ring, and terphenyl rings such as terphenyl ring.

[0072] A preferred ring Ar is C 6-14 Aromatic hydrocarbon rings, more preferably C 6-12 Aromatic hydrocarbon rings (e.g., benzene rings, naphthalene rings, biphenyl rings, etc.), particularly benzene rings or naphthalene rings (especially naphthalene rings) are preferred.

[0073] In formula (1) above, the number of substitutions n of the mercapto group (or thiol group) [-SH] may be, for example, an integer from 1 to 8 (for example, an integer from 1 to 6), preferably an integer from 1 to 5 (for example, an integer from 1 to 4), and more preferably an integer from 1 to 3 (for example, 2). The substitution position of the mercapto group is not particularly limited.

[0074] R 1 The substituents represented by may be any group other than a mercapto group, and examples include substituted or unsubstituted hydrocarbon groups (hydrocarbon groups that may have substituents), nitrogen atom-containing groups, oxygen atom-containing groups, sulfur atom-containing groups, halogen atoms (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom, etc.).

[0075] Examples of the hydrocarbon group include (linear or branched) aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups formed by combining two or more of these groups.

[0076] The aliphatic hydrocarbon group may be linear or branched. Furthermore, the aliphatic hydrocarbon group may be an alkyl group (saturated aliphatic hydrocarbon group), or an unsaturated aliphatic hydrocarbon group such as an alkenyl group.

[0077] Examples of alkyl groups include methyl group, ethyl group, propyl group (n-propyl group, isopropyl group), butyl group (n-butyl group, isobutyl group, sec-butyl group, tert-butyl group), pentyl group (n-pentyl group, isopentyl group, neopentyl group, etc.), hexyl group (n-hexyl group, etc.), heptyl group (n-heptyl group, etc.), octyl group (n-octyl group, 2-ethylhexyl group, etc.), nonyl group, decyl group, undecyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, eicosyl group, etc. 1-30 Alkyl (e.g., C 1-24 (such as alkyl groups), preferably C 1-18 Alkyl (e.g., C 1-12 (such as alkyl groups), more preferably C 1-8 Alkyl (e.g., C 1-6 (Alkyl alkyl groups, etc.), especially C 1-4 Alkyl groups (e.g., C such as a methyl group) 1-3 Examples include alkyl groups, etc.

[0078] Examples of unsaturated aliphatic hydrocarbon groups include groups having at least one unsaturated bond (carbon-carbon unsaturated bond, such as an ethylenically unsaturated bond (C=C double bond), an acetylenely unsaturated bond (C≡C triple bond), etc.) corresponding to the alkyl groups described above, and may also be alkenyl groups. Examples of alkenyl groups include vinyl groups, propenyl groups (allyl group, isopropenyl group, etc.), butenyl groups (2-methylallyl group, clotyl group, etc.), etc. 2-10 Examples include alkenyl groups.

[0079] Alicyclic hydrocarbon groups may be saturated or unsaturated. They may also be monocyclic (cycloalkyl groups, cycloalkenyl groups, cycloalkadienyl groups, cyclopolyenyl groups, etc.) or polycyclic (ring aggregates, bridging rings, spirocyclic rings, etc.).

[0080] Examples of saturated, monocyclic alicyclic hydrocarbon groups (cycloalkyl groups) include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and cyclodecyl groups. 3-20 Cycloalkyl groups, preferably C 4-12 Cycloalkyl groups, more preferably C 5-10 Examples include cycloalkyl groups.

[0081] Examples of unsaturated, monocyclic alicyclic hydrocarbon groups [such as cycloalkenyl groups, cycloalkadienyl groups (or cyclopolyenyl groups)] include groups having at least one ethylenically unsaturated bond (double bond), corresponding to the cycloalkyl groups exemplified above, specifically such as cyclopentenyl groups and cyclohexenyl groups. 3-20 C such as cycloalkenyl group, cyclopentadienyl group, etc. 4-20 Examples include cycloalkadienyl groups.

[0082] Polycyclic alicyclic hydrocarbon groups may be ring aggregates in which two or more aliphatic rings are directly bonded to each other, or they may be spirocyclic or bridging rings in which two or more aliphatic rings share one or more atoms. Examples of such aliphatic rings include those corresponding to the monocyclic group. Typical polycyclic alicyclic hydrocarbon groups include, for example, bicyclohexyl groups and other C3 groups. 6-20 C such as cyclic aggregated alicyclic hydrocarbon groups, norbornyl groups, adamantyl groups, etc. 4-20 Examples include cross-linked cyclic and alicyclic hydrocarbon groups.

[0083] Aromatic hydrocarbon groups include aryl groups, which may be monocyclic aryl groups (such as phenyl groups) or polycyclic aryl groups. Polycyclic aryl groups include fused ring groups in which two or more rings (such as benzene rings) are fused together sharing two or more atoms (for example, naphthyl groups, anthryl groups, phenanthryl groups, etc.). 10-24It may also be a fused aryl group, and a ring assembly in which two or more rings (such as benzene rings) are directly bonded (for example, a biphenyl group, phenylnaphthyl group, naphthylphenyl group, binaphthyl group, terphenyl group, etc.). 12-28 This may include ring-assembled aryl groups, etc.

[0084] Examples of hydrocarbon groups formed by combining two or more of the aforementioned groups include cycloalkyl-alkyl groups (for example, C such as cyclohexylmethyl group). 3-20 Cycloalkyl C 1-6 Alkyl groups, etc.); alkylaryl groups (for example, mono- to penta-C groups such as methylphenyl (tolyl) group and dimethylphenyl (xylyl) group). 1-6 Alkyl C 6-20 aryl groups, etc.; aralkyl groups (e.g., benzyl group, phenethyl group, etc.) 6-20 Aryl C 1-6 Alkyl groups, etc.); aryl alkenyl groups (e.g., phenyl vinyl group (styryl group), cinnamyl group, ethyl cinnamyl group, etc.) 6-20 Aryl C 2-6 Examples include alkenyl groups.

[0085] These hydrocarbon groups may have substituents (they may be substituted). Examples of substituents that the hydrocarbon groups may have include halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.). The hydrocarbon groups may have these substituents individually or in combination of two or more. Preferred substituents for the hydrocarbon groups include hydroxyl groups, carboxyl groups, halogen atoms, and more preferably halogen atoms such as chlorine atoms and bromine atoms. The number of substituents (substituents that the hydrocarbon groups may have) that substitute for the hydrocarbon groups may be one or two or more (e.g., 1 to 3, preferably 1 to 2, more preferably 1), or it may be zero (the hydrocarbon groups may have no substituents).

[0086] Examples of the nitrogen atom-containing group include amino groups, substituted amino groups (mono- or dialkylamino groups, mono- or diacylamino groups, etc.), nitro groups, cyano groups, and groups in which these groups are substituted on the hydrocarbon group (for example, aminoalkyl groups, substituted aminoalkyl groups, nitroalkyl groups, cyanoalkyl groups, etc.).

[0087] Examples of the oxygen atom-containing groups include hydroxyl groups, hydroxy(poly)alkoxy groups (e.g., 2-hydroxyethoxy groups), and groups [-OR h1 ](wherein, R h1 is a hydrocarbon group, for example, the R 1 Examples of substituted or unsubstituted hydrocarbon groups are shown. )[For example, alkoxy groups such as methoxy groups, cycloalkyloxy groups such as cyclohexyloxy groups, aryloxy groups such as phenoxy groups, aralkyloxy groups such as benzyloxy groups, vinyloxy groups, allyloxy groups, preferably alkoxy groups, etc.], formyl groups, acyl groups (for example, alkylcarbonyl groups such as acetyl groups, arylcarbonyl groups such as benzoyl groups, etc.), acyloxy groups (for example, alkylcarbonyloxy groups such as acetyloxy groups, etc.), (meth)acryloyl groups, (meth)acryloyloxy groups, carboxyl groups, groups [-C(=O)-OR h2 ](wherein, R h2 is a hydrocarbon group, for example, the R 1Examples of substituted or unsubstituted hydrocarbon groups include: [for example, methoxycarbonyl group, ethoxycarbonyl group, tert-butoxycarbonyl group and other alkoxycarbonyl groups], amide groups (or aminocarbonyl groups), substituted aminocarbonyl groups (for example, alkylaminocarbonyl groups), epoxy ring-containing groups (epoxy group, glycidyl group, glycidyloxy group, β-methylglycidyl group, β-methylglycidyloxy group, epoxidized cyclohexenyl group, etc.), oxetane ring-containing groups (for example, oxetanyl group), furyl groups, and groups in which these groups are substituted on the hydrocarbon groups (for example, hydroxymethyl group, hydroxyethyl group and other hydroxyalkyl groups, hydroxy(poly)alkoxyalkyl groups, methoxymethyl group and other alkoxyalkyl groups, (meth)acryloyloxyalkyl groups, etc.).

[0088] Examples of the sulfur atom-containing group include mercapto(poly)alkoxy groups (e.g., 2-mercaptoethoxy group, etc.) and groups [-SR] h3 ](wherein, R h3 is a hydrocarbon group, for example, the R 1Examples of substituted or unsubstituted hydrocarbon groups are shown. ) [e.g., alkylthio groups such as methylthio groups, cycloalkylthio groups such as cyclohexylthio groups, arylthio groups such as phenylthio groups, aralkylthio groups such as benzylthio groups, etc.], alkyl(thiocarbonyl) groups [e.g., methyl(thiocarbonyl) group, etc.], alkoxy(thiocarbonyl) groups [e.g., methoxy(thiocarbonyl) group, etc.], thio(meth)acryloyl groups, thio(meth)acryloyloxy groups [e.g., thio(meth)acryloyloxy groups, etc.], thioamide groups (or thiamide groups), substitution Examples include thioamide groups [e.g., alkyl(thioamide) groups], thiirane ring-containing groups [e.g., thiiranyl group (or 1,2-epithioethyl group), thiiranylmethyl group (or 2,3-epithiopropyl group)], thienyl groups, and groups in which these groups are substituted for the hydrocarbon group (e.g., mercaptoalkyl groups (e.g., mercaptomethyl group, mercaptoethyl group), mercapto(poly)alkoxyalkyl groups (e.g., mercaptoethoxyethyl group), alkylthioalkyl groups such as methylthiomethyl group, etc.).

[0089] R 1 The substituent represented by may be present individually or in combination of two or more. Of these, the preferred substituent R 1 Examples include substituted or unsubstituted hydrocarbon groups, oxygen atom-containing groups [e.g., hydroxyl groups, hydroxy(poly)alkoxy groups, and groups [-OR h1 ](e.g., alkoxy group), acyl group, acyloxy group, (meth)acryloyl group, (meth)acryloyloxy group, carboxyl group, group [-C(=O)-OR h2 ](e.g., alkoxycarbonyl group), amide group (or aminocarbonyl group), substituted aminocarbonyl group, epoxy ring-containing group (epoxy group, glycidyl group, glycidyloxy group, etc.), oxetane ring-containing group (oxetanyl group, etc.)), sulfur atom-containing group [mercapto(poly)alkoxy group, group [-SR h3Examples include alkylthio groups, halogen atoms, etc., and more preferably substituted or unsubstituted hydrocarbon groups, halogen atoms (chlorine atoms, etc.), among which substituted or unsubstituted hydrocarbon groups (e.g., aliphatic or alicyclic hydrocarbon groups), and especially saturated aliphatic hydrocarbon groups such as alkyl groups (e.g., C such as methyl groups). 1-6 It may also be an alkyl group, etc.

[0090] Substituent R 1 The number of permutations p can be any integer greater than or equal to 0, for example, an integer between 0 and 6 (for example, an integer between 0 and 5), preferably an integer between 0 and 4 (for example, an integer between 1 and 3), and even more preferably an integer between 0 and 2 (for example, 0 or 1, especially 0). If p is 2 or greater, then 2 or greater R 1 The types may be the same or different from each other. If p is 1 or greater, R 1 The substitution site is not particularly restricted; it can be any position other than the mercapto group's binding site.

[0091] Examples of typical compounds represented by formula (1) include benzenethiol compounds (e.g., benzenethiol (or thiophenol), benzenedithiol, and other benzene mono or trithiols), naphthalenchiol compounds [e.g., compounds represented by the following formula (1A)].

[0092] [ka]

[0093] (In the formula, n represents an integer from 1 to 8, R 1 (where 'x' indicates a substituent, and 'p' represents an integer from 0 to (8-n)).

[0094] In formula (1A), the number of substitutions n of the mercapto group can be, for example, the same numerical range as in formula (1), and may also be the same in preferred embodiments.

[0095] In formula (1A) above, the substitution position of the mercapto group is not particularly limited, and examples include the 1-, 2-, 1,4-, 1,5-, 1,6-, 1,8-, 2,6-, 2,7-, and 1,3,6- positions, and preferably the 1-, 2-, 1,5-, 1,6-, 2,6-, 2,7-, and 1,3,6- positions. From the viewpoint of not only suppressing the increase of polymers (especially dimers) but also being easily and effectively reduced, naphthalenchiol compounds in which the mercapto group is directly bonded to the 1,6-, 2,6-, or 2,7- positions are even more preferred.

[0096] In the above formula (1A), substituent R 1 And the number of substitutions p can be, for example, the same substituents and numerical ranges as in formula (1) above, and may be the same in preferred embodiments. If p is 2 or more, then 2 or more R 1 The types may be the same or different from each other. If p is 1 or greater, R 1 The substitution site is not particularly restricted; it can be any position other than the mercapto group's binding site.

[0097] Representative naphthalenthol compounds represented by formula (1A) include, for example, 1-naphthalenthol, 2-naphthalenthol, 1,4-naphthalenedithiol, 1,5-naphthalenedithiol, 1,6-naphthalenedithiol, 1,8-naphthalenedithiol, 2,6-naphthalenedithiol, 2,7-naphthalenedithiol, 1,3,6-naphthalenthiliol, and substituents R corresponding to these naphthalenthol compounds. 1 For example, hydrocarbon groups such as alkyl groups (e.g., C groups such as methyl groups) 1-6 Groups such as alkyl groups, alkoxy groups, etc. [-OR h1 ](For example, C such as a methoxy group 1-6Examples include naphthalenthol compounds which may have an alkoxy group, etc.; preferably 1-naphthalenthol, 2-naphthalenedithiol, 1,5-naphthalenedithiol, 1,6-naphthalenedithiol, 2,6-naphthalenedithiol, 2,7-naphthalenedithiol, 1,3,6-naphthalenthol, and substituent R corresponding to these naphthalenthol compounds. 1 For example, hydrocarbon groups such as alkyl groups (e.g., C groups such as methyl groups) 1-4 Groups such as alkyl groups, alkoxy groups, etc. [-OR h1 ](For example, C such as a methoxy group 1-4 Examples include naphthalenchiol compounds which may have an alkoxy group, etc.; from the viewpoint of not only suppressing the increase of polymers (especially dimers) but also being easily and effectively reduced, 1,6-naphthalendithiol, 2,6-naphthalendithiol, 2,7-naphthalendithiol, and substituent R corresponding to these naphthalenchiol compounds. 1 For example, hydrocarbon groups such as alkyl groups (e.g., C groups such as methyl groups) 1-3 Groups such as alkyl groups, alkoxy groups, etc. [-OR h1 ](For example, C such as a methoxy group 1-3 Naphthalenchiol compounds that may have an alkoxy group or the like are even more preferred.

[0098] The molecular weight of the aromatic thiol compound (e.g., naphthalenchiol compound) may be, for example, 2000 or less (e.g., 160 to 1000), preferably 500 or less (e.g., 160 to 300), and more preferably 230 or less. If the molecular weight is too high, purification may become difficult.

[0099] The refractive index of aromatic thiol compounds (e.g., naphthalenchiol compounds) at a temperature of 25°C and a wavelength of 589 nm may be, for example, 1.6 or higher (e.g., 1.63 to 1.8), preferably 1.65 to 1.79, and more preferably around 1.7 to 1.78 (e.g., 1.71 to 1.73). Because aromatic thiol compounds (e.g., naphthalenchiol compounds) exhibit a high refractive index, they can be effectively used as refractive index improvers (resin additives) to improve the refractive index of organic compounds (resins, etc.).

[0100] In this specification and in the claims, the refractive index can be measured in accordance with the method described in the examples below.

[0101] The melting point of aromatic thiol compounds (e.g., naphthalenchiol compounds) may be in the range of, for example, 230°C or less (e.g., 0 to 200°C), and they may be liquid at room temperature. The melting point appears to vary considerably depending on the type of aromatic thiol compound and the substitution position of the mercapto group.

[0102] In this specification and in the claims, the melting point can be measured in accordance with the method described in the examples below.

[0103] The 5% weight loss temperature of aromatic thiol compounds (e.g., naphthalenchiol compounds) may be, for example, 150-270°C (e.g., 160-240°C), preferably around 170-220°C. If the 5% weight loss temperature is too low, the purity may easily decrease due to high heat treatment, making purification operations such as distillation difficult. The 5% weight loss temperature appears to vary considerably depending on the type of aromatic thiol compound and the substitution position of the mercapto group.

[0104] In this specification and in the claims, the 5% weight loss temperature can be measured according to the method described in the examples below.

[0105] (Method for preparing aromatic thiol compounds) The method for preparing the raw material aromatic thiol compound before purification by the purification method of the present invention (for example, a crude raw material, crude product, or crude for use in the base mixing step, such as a raw material naphthalenthol compound) is not particularly limited, and known methods for synthesizing aromatic thiol compounds, such as methods using aromatic sulfonic acid compounds (for example, naphthalene sulfonic acid compounds) or salts thereof as raw materials, can be used. Specifically, (i) a halosulfonyl compound [for example, a (halosulfonyl)naphthalene compound] may be prepared by reacting the corresponding aromatic sulfonic acid compound (for example, a naphthalene sulfonic acid compound) or a salt thereof (preferably a salt) with a halogenating agent, and (ii) the resulting halosulfonyl compound may be prepared by reducing it in the presence of a reducing agent.

[0106] In (i) above, examples of aromatic sulfonic acid compounds include aromatic sulfonic acid compounds in which a sulfonic acid group (or sulfo group) is bonded in place of the mercapto group, corresponding to the substitution position of the mercapto group of the target aromatic thiol compound, such as benzene mono or trisulfonic acid compounds and naphthalene mono or trisulfonic acid compounds.

[0107] Examples of salts of aromatic sulfonic acid compounds include alkali metal salts (e.g., sodium salts, potassium salts, etc.) and ammonium salts, with alkali metal salts such as sodium salts being preferred.

[0108] Examples of halogenating agents include phosgene, phosphorus pentachloride, phosphorus trichloride, phosphorus oxychloride, sulfuryl chloride, oxalyl chloride, and thionyl halogenates such as thionyl chloride. Halogenating agents can be used alone or in combination of two or more. Preferred halogenating agents are chlorinating agents such as thionyl chloride.

[0109] The proportion of the halogenating agent may be, for example, 1 to 10 moles (e.g., 1 to 5 moles), preferably 1.05 to 2 moles (e.g., 1.1 to 1.5 moles), per mole of sulfonic acid groups (or salts) of an aromatic sulfonic acid compound (e.g., naphthalene sulfonic acid compound) (or salt thereof).

[0110] The reaction may be carried out in or without a catalyst. Examples of catalysts include amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (preferably N,N-substituted amide compounds such as DMF); pyridines such as pyridine and 4-(N,N-dimethylamino)pyridine; and tertiary amines such as triethylamine. The catalyst may be used alone or in combination of two or more. Preferred catalysts are amides such as DMF (N,N-substituted amide compounds), more preferably DMF, DMAc, and especially DMF. The proportion of catalyst may be, for example, 0.01 to 1 mole, preferably 0.1 to 0.7 moles, and more preferably 0.2 to 0.5 moles (for example, 0.3 to 0.5 moles) per mole of aromatic sulfonic acid compound (e.g., naphthalene sulfonic acid compound) or its salt. Furthermore, amides such as DMF and chlorinating agents such as thionyl chloride may form a Vilsmeyer complex and undergo sulfonyl chloride formation.

[0111] The reaction may be carried out in or without a solvent. Suitable solvents include reaction-inert solvents such as hydrocarbons like hexane, heptane, cyclohexane, toluene, and xylene; halogenated hydrocarbons (halogens such as chlorinated hydrocarbons) like dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene, and dichlorobenzene; esters like methyl acetate and ethyl acetate; ketones like methyl ethyl ketone and methyl isobutyl ketone; ethers like tetrahydrofuran and dioxane; nitriles like acetonitrile and propionitrile; and sulfoxides like dimethyl sulfoxide. The solvent can be used alone or in combination of two or more as a mixed solvent. Preferred solvents include aromatic hydrocarbons like toluene and xylene, and chlorinated hydrocarbons like dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene, and dichlorobenzene, with aromatic hydrocarbons like toluene and xylene being more preferred. The proportion of the solvent is not particularly limited, and may be, for example, 10 to 5000 parts by mass (e.g., 100 to 3000 parts by mass), preferably 300 to 2500 parts by mass, and more preferably about 400 to 2100 parts by mass, per 100 parts by mass of the naphthalene sulfonic acid compound or its salt.

[0112] The reaction temperature may be, for example, 50 to 150°C, preferably 80 to 120°C, and more preferably 90 to 110°C. The reaction time may be, for example, 0.5 to 24 hours, preferably 1 to 12 hours, and more preferably 2 to 8 hours.

[0113] The reaction may be carried out in an air or inert gas atmosphere (e.g., nitrogen gas; noble gases such as argon or helium), preferably an inert gas atmosphere. The reaction may also be carried out under normal pressure, under pressure, or under reduced pressure.

[0114] After the reaction is complete, the reaction product (reaction mixture) may be separated and purified by conventional separation and purification methods such as washing, extraction, concentration, filtration, crystallization, centrifugation, column chromatography, activated carbon treatment, and drying, or by methods combining these, or it may be subjected to the reduction reaction in (ii) above without separation and purification (for example, in solution). In a preferred method, in order to deactivate the halogenating agent, water may be added to the reaction mixture and stirred, and the operation of separating it into an organic phase and an aqueous phase may be repeated at least once or more times. The separated organic phase may be separated and purified by operations such as drying, drying to dryness, distillation, and crystallization if necessary, and subjected to the subsequent reduction reaction. In a preferred embodiment, the separated organic phase may be subjected to the subsequent reduction reaction in (ii). In addition, if the solubility of the halosulfonyl compound [for example, a (halosulfonyl)naphthalene compound, etc.] is low, the precipitated halosulfonyl compound may be recovered by filtration and subjected to the subsequent reduction reaction in (ii).

[0115] In the reduction reaction (ii) described above, examples of halosulfonyl compounds include (halosulfonyl)benzene compounds and (halosulfonyl)naphthalene compounds [for example, mono- or tri(chlorosulfonyl)naphthalene compounds such as mono- or tri(chlorosulfonyl)naphthalene].

[0116] In the reduction reaction described in (ii) above, the type of reducing agent is not particularly limited, and examples include combinations of zinc (such as zinc powder) and acid, combinations of iron (such as iron powder) and acid, combinations of tin and acid, combinations of tin chloride and acid, and the reducing agents described above (for example, lithium aluminum hydride, lithium borohydride, sodium borohydride, etc.). The reducing agent can be used alone or in combination of two or more types. A preferred reducing agent is a combination of zinc (such as zinc powder) and acid. The proportion of the reducing agent may be, for example, 5 to 20 moles, preferably 8 to 17 moles, and more preferably about 10 to 15 moles per mole of the halosulfonyl compound [for example, (halosulfonyl)naphthalene compound, etc.].

[0117] Examples of acids include inorganic acids such as hydrochloric acid and sulfuric acid, with hydrochloric acid being preferred. Acids can be used alone or in combination of two or more. The ratio of acid may be, for example, 10 to 100 moles, preferably 15 to 60 moles, and more preferably 20 to 50 moles (for example, 25 to 45 moles) per mole of halosulfonyl compound [for example, (halosulfonyl)naphthalene compound]. The acid may also be used as an aqueous solution.

[0118] The reaction may be carried out in the presence of a solvent, and examples of solvents include those used in the (i) halosulfonylation reaction, and these can be used alone or in combination of two or more solvents. When using the acid, water contained in aqueous solution may also be used as a solvent. In particular, (ii) the reduction reaction is preferably carried out in the presence of water that can be liquid-liquidated with respect to the reaction solvent (hydrophobic aromatic hydrocarbons, etc.) after the reaction is complete. The proportion of the solvent is not particularly limited, and may be, for example, 100 to 10,000 parts by mass, preferably about 500 to 5,000 parts by mass, per 100 parts by mass of the halosulfonyl compound [for example, (halosulfonyl)naphthalene compounds, etc.].

[0119] The reaction temperature may be, for example, 30 to 120°C, preferably 40 to 100°C, and more preferably 50 to 80°C (for example, 60 to 70°C). The reaction time may be, for example, 0.5 to 24 hours, preferably 1 to 12 hours, and more preferably 2 to 5 hours.

[0120] The reaction may be carried out in air, preferably in an inert gas atmosphere (e.g., nitrogen gas; noble gases such as argon or helium). The reaction may also be carried out under normal pressure, under pressure, or under reduced pressure.

[0121] After the reaction is complete, the reaction product may be separated and purified by conventional separation and purification methods (or treatments) such as washing, liquid-liquid extraction or extraction, concentration, neutralization, crystallization or precipitation, solid-liquid separation (filtration, centrifugation, etc.), column chromatography, adsorption treatment (treatment with porous materials such as activated carbon, etc.), drying or drying, distillation (vacuum distillation, etc.), or a combination thereof, and then subjected to the purification method of the present invention. Alternatively, it may be subjected to the purification method of the present invention in the form of a reaction mixture or the like without separation and purification.

[0122] (Purity of aromatic thiol compounds, etc.) The content (purity or absolute purity) of the raw material aromatic thiol compound before purification by the purification method of the present invention (for example, a crude raw material, crude product, or crude for use in the base mixing step, such as a raw material naphthalenchiol compound) may be, for example, 50% by mass or more (for example, 70% by mass or more, but less than 100% by mass), preferably 80% by mass or more (for example, 85% by mass or more), and more preferably 90% by mass or more (for example, 95 to 99.5% by mass). Furthermore, the content (purity or absolute purity) of the purified product after purification may be, for example, 80% by mass or more (90 to 100% by mass), preferably 95% by mass or more (for example, 97% by mass or more), and more preferably 98% by mass or more (for example, 98.5 to 100% by mass). Generally, it is difficult to further purify a crude raw material (crude product or crude) that is already relatively pure before purification, and this tendency is expected to become more pronounced the higher the purity before purification. However, the purification method of the present invention makes it possible to easily or efficiently increase the purity of the purified product even if the content (purity or absolute purity) of the crude raw material (crude product or crude) before purification is high.

[0123] The purity of the raw material aromatic thiol compound before purification by the purification method of the present invention (for example, a crude raw material, crude product, or crude for use in the base mixing step, such as a raw material naphthalenchiol compound) in area percentage by high-performance liquid chromatography (HPLC) (HPLC purity) may be, for example, 50% or more (e.g., 70-100%), preferably 80% or more (e.g., 85% or more), more preferably 90% or more (e.g., 95-99.5%), and particularly preferably 98% or more (e.g., 99-99.5%). Furthermore, the HPLC purity of the purified product after purification may be, for example, 80% or more (e.g., 90-100%), preferably 95% or more (e.g., 98% or more), and more preferably 98.5% or more (e.g., 99% or more). Generally, it is difficult to further purify a relatively high-purity crude raw material (crude product or crude) before purification, and this tendency is expected to become more pronounced the higher the purity before purification. However, the purification method of the present invention allows for easy and efficient purification even when the HPLC purity before purification is high.

[0124] The content of the polymer (area percentage by HPLC) of the raw material aromatic thiol compound before purification by the purification method of the present invention (for example, the crude raw material, crude product, or crude used in the base mixing step, such as a raw material naphthalenchiol compound) may be, for example, 10% or less (e.g., 0-5%), preferably 3% or less (e.g., 2% or less), more preferably 1.5% or less (e.g., 0.1-1%), and particularly preferably 0.5% or less (e.g., 0.1-0.3%). Furthermore, the content of the polymer in the purified product after purification may be, for example, 5% or less (e.g., 0-3%), preferably 2% or less (e.g., 1% or less), more preferably 0.5% or less (e.g., 0.1-0.4%), and particularly preferably 0.3% or less (e.g., 0-0.2%), and may be below the detection limit. The polymer may be a dimer of the aromatic thiol compound. That is, the content (percentage) of the dimer may be in the above proportions. In the purification method of the present invention, aromatic thiol compounds that are more easily oxidized than ordinary primary to tertiary thiol compounds are used, and despite undergoing a base mixing step under basic (or alkaline) conditions that promote oxidation, the disulfide content can surprisingly not increase, but may even be reduced. Therefore, the present invention also includes a method for reducing the content (percentage) of polymers in aromatic thiol compounds.

[0125] Furthermore, dimers often have lower solubility in organic solvents compared to monomeric aromatic thiol compounds, and polymers of trimers or more appear to have even lower solubility than dimers. Therefore, it is usually difficult to quantify these polymers of trimers or more by HPLC.

[0126] The raw material aromatic thiol compound before purification by the purification method of the present invention (for example, a crude raw material, crude product, or crude for use in the base mixing step, such as a raw material naphthalenchiol compound) may or may not become turbid when dissolved in acetonitrile at a concentration of 0.13% by mass at 10-30°C. However, the purified product after purification may or may not become turbid when dissolved in acetonitrile at a concentration of 0.13% by mass at 10-30°C.

[0127] In the purification method of the present invention, the yield of the purified aromatic thiol compound (such as a naphthalenthol compound) after purification relative to the raw material aromatic thiol compound before purification (for example, a crude raw material, crude product, or crude for the base mixing step, such as a raw material naphthalenthol compound) may be, for example, 80 mol% or more (for example, 85 mol% or more), preferably 90 to 100 mol% (for example, 95 to 99.5 mol%), and particularly 97 to 100 mol% (for example, 98 to 99 mol%).

[0128] [Derivatives of aromatic thiol compounds] The aromatic thiol compounds (e.g., naphthalenchiol compounds) obtained by the purification method of the present invention are of high purity, have a high refractive index, and possess highly reactive mercapto groups. Therefore, the aromatic thiol compounds themselves may be used as reaction reagents, additives (such as resin additives), polymer raw materials (monomers), optical materials, or intermediates thereof. Aromatic thiol derivatives (e.g., naphthalenchiol derivatives) derived from the aromatic thiol compounds obtained by the purification method of the present invention may also be used for similar purposes. By using the purification method of the present invention, such aromatic thiol derivatives can also be easily prepared to high purity and are useful. Furthermore, since such aromatic thiol derivatives also exhibit a high refractive index, they can be effectively used as optical materials and the like.

[0129] The aromatic thiol derivative is not particularly limited as long as it is a compound derived from an aromatic thiol compound, but examples include the compound represented by the following formula (2), specifically the naphthalenthol derivative represented by the following formula (2A).

[0130] [ka]

[0131] (In the formula, Ar represents an aromatic hydrocarbon ring (arene ring), R 2 represents a substituent, and n represents an integer greater than or equal to 1. R1 (where represents a substituent and p represents a non-negative integer).

[0132] [ka]

[0133] (In the formula, R 2 represents a substituent, and n represents an integer from 1 to 8. R 1 (where 'x' indicates a substituent, and 'p' represents an integer from 0 to (8-n)).

[0134] In equations (2) and (2A) above, Ar, n, R 1 Examples of p, including preferred embodiments, can be found in formula (1) above.

[0135] R 2 Examples of substituents represented by the formula (3) below include at least one group selected from the groups represented by the formula (3) below (a monovalent group).

[0136] [ka]

[0137] [In the formula, A 1 X indicates an alkylene group, 1 represents an oxygen atom or a sulfur atom, and m represents an integer of 0 or greater than or equal to 1. Y 1 represents one of the monovalent groups selected from the following equations (3a) to (3f).

[0138] [ka]

[0139] (In the formula, R 3 This represents a saturated hydrocarbon group which may have a halogen atom, A 2 This indicates a direct bond (single bond) or an alkylene group. R4 , R 5 and R 6 each independently represents a hydrogen atom, or a substituted or unsubstituted hydrocarbon group, R 7 represents a hydrogen atom or a methyl group, X 2 represents an oxygen atom or a sulfur atom, R 8 represents a hydrogen atom or a methyl group, A 3 represents an alkylene group, R 9 represents a hydroxyl group, a group [-OR 10 (wherein R 10 represents a substituted or unsubstituted hydrocarbon group), or a halogen atom). <​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​and X 1 The types may be different, but it is preferable that they be the same.

[0143] R 3 In a saturated hydrocarbon group which may have a halogen atom represented by , examples of saturated hydrocarbon groups include alkyl groups, and examples of alkyl groups include R 1 Examples of alkyl groups similar to those exemplified in the above example include C, preferably a methyl group, an ethyl group, etc. 1-6 Examples include alkyl groups. Halogen atoms that a saturated hydrocarbon group may have include, for example, chlorine atoms and bromine atoms (preferably chlorine atoms), and may be present individually or in combination of two or more. The number of halogen atoms may be, for example, 0 to 2, preferably 0 or 1 (especially 0).

[0144] A 2 This represents a direct bond (single bond) or an alkylene group, and as an alkylene group, A 1 Examples similar to the alkylene group exemplified above can be given. Preferred A 2 This is a direct bond, or a C such as a methylene group. 1-3 It may also be an alkylene group.

[0145] R 4 , R 5 and R 6 R represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group, and R represents a substituted or unsubstituted hydrocarbon group. 1 Similar groups to those exemplified in the above can be exemplified. Preferred R 4 , R 5 and R 6 It may be a hydrogen atom.

[0146] R 7 This can be either a hydrogen atom or a methyl group, but a methyl group is preferred from the viewpoint of stability.

[0147] X 2 This may be either an oxygen atom or a sulfur atom, with an oxygen atom being preferred.

[0148] R 8 This can be either a hydrogen atom or a methyl group, with a hydrogen atom being preferred.

[0149] A 3 This represents an alkylene group, and the A 1 Examples similar to the alkylene group exemplified above can be given. Preferred A 3 C is a methylene group, etc. 1-3 It may also be an alkylene group.

[0150] R 9 is a hydroxyl group, group [-OR 10 ](wherein, R 10 ) indicates a substituted or unsubstituted hydrocarbon group. ) or indicates a halogen atom, R 10 For example, R 1 Similar groups to those exemplified in the above can be exemplified, and preferred R 10 C is an alkyl group (for example, a methyl group, an ethyl group, etc.) 1-6 It may also be an alkyl group, etc. Preferred R 9 These are groups such as hydroxyl groups and alkoxy groups [-OR 10 ] (especially a hydroxyl group) may also be used.

[0151] In equation (3) above, Y 1 Examples of a group whose formula is (3a) [hereinafter also referred to as group (3a)] include a hydrogen atom, a hydroxyalkyl group (for example, a hydroxyethyl group, a hydroxypropyl group, etc.), and a hydroxy-C group. 2-6 Examples include alkyl groups, hydroxy-(poly)alkoxy-alkyl groups (e.g., hydroxyethoxyethyl group), mercaptoalkyl groups (e.g., mercaptoethyl group), and mercapto-(poly)alkylthio-alkyl groups (e.g., mercaptoethylthioethyl group).

[0152] Preferred groups (3a) include hydrogen atoms and hydroxyalkyl groups, and more preferably hydroxyalkyl groups (e.g., hydroxyethyl group, etc.). 2-4It may also be an alkyl group, etc.

[0153] In equation (3) above, Y 1 Examples of groups whose formula is (3b) [hereinafter also referred to as group (3b)] include alkyl groups (such as methyl, ethyl, and butyl groups). 1-12 Examples include alkyl groups, alkoxyalkyl groups (e.g., methoxyethyl group), polyalkoxyalkyl groups (e.g., methoxyethoxyethyl group), alkylthioalkyl groups (e.g., methylthioethyl group), polyalkylthioalkyl groups [e.g., methylthioethylthioethyl group], and groups in which one or more halogen atoms (e.g., chlorine atoms) are substituted on these groups [e.g., haloalkyl groups such as chloroalkyl groups (e.g., chloroethyl group), bromoalkyl groups (e.g., bromoethyl group), and haloalkoxyalkyl groups such as chloroethoxyethyl group].

[0154] A preferred group (3b) is an alkyl group (C 1-6 Alkyl groups, etc.), haloalkyl groups (haloC groups such as chloroethyl groups) 1-6 (such as alkyl groups), more preferably alkyl groups (such as methyl groups and C 1-4 (Algorithms, etc.) may also be used.

[0155] In equation (3) above, Y 1 Examples of groups whose formula is (3c) [hereinafter also referred to as group (3c)] include alkenyl groups [for example, vinyl groups, propenyl groups (allyl groups, isopropenyl groups, etc.) C]. 2-10 Examples include alkenyl groups, alkenyloxyalkyl groups (e.g., vinyloxyethyl group, allyloxyethyl group), alkenyl-(poly)alkoxyalkyl groups (e.g., vinyloxyethoxyethyl group, allyloxyethoxyethyl group), alkenylthioalkyl groups (e.g., vinylthioethyl group, allylthioethyl group), and alkenyl-(poly)alkylthioalkyl groups (e.g., vinylthioethylthioethyl group, allylthioethylthioethyl group).

[0156] Preferred group (3c) is an alkenyl group (e.g., vinyl group, allyl group, isopropenyl group, etc.). 2-6 C (such as an alkenyl group), more preferably a vinyl group, an allyl group, etc. 2-4 It may also be an alkenyl group, etc.

[0157] In equation (3) above, Y 1 Examples of groups whose formula is (3d) [hereinafter also referred to as group (3d)] include (meth)acryloyl groups and (meth)acryloyloxyalkyl groups [for example, (meth)acryloyloxyethyl groups, (meth)acryloyloxypropyl groups, etc. (meth)acryloyloxy C 2-6 Examples include alkyl groups, (meth)acryloyloxy-(poly)alkoxy-alkyl groups [e.g., (meth)acryloyloxyethoxyethyl group], (meth)acryloylthioalkyl groups [e.g., (meth)acryloylthioethyl group], and (meth)acryloylthio-(poly)alkylthio-alkyl groups [e.g., (meth)acryloylthioethylthioethyl group].

[0158] Preferred groups (3d) include (meth)acryloyl groups and (meth)acryloyloxyalkyl groups [for example, (meth)acryloyloxyethyl groups and other (meth)acryloyloxy C groups]. 2-4 Alkyl groups, and more preferably (meth)acryloyl groups (especially methacryloyl groups).

[0159] In equation (3) above, Y 1 Examples of groups whose formula is (3e) [hereinafter also referred to as group (3e)] include glycidyl groups and glycidyloxyalkyl groups (for example, glycidyloxyethyl groups, glycidyloxypropyl groups, etc.). 2-6Examples include alkyl groups, glycidyloxy-(poly)alkoxy-alkyl groups (e.g., glycidyloxyethoxyethyl group), glycidylthioalkyl groups (e.g., glycidylthioethyl group), glycidylthio-(poly)alkylthio-alkyl groups (e.g., glycidylthioethylthioethyl group), and groups obtained by replacing the glycidyl group with a β-methylglycidyl group, a 2,3-epithiopropyl group, or a 2-methyl-2,3-epithiopropyl group, corresponding to these groups.

[0160] Preferred groups (3e) may include glycidyl group, β-methylglycidyl group, 2,3-epithiopropyl group, and more preferably glycidyl group, β-methylglycidyl group (especially glycidyl group).

[0161] In equation (3) above, Y 1 Examples of groups whose formula is (3f) [hereinafter also referred to as group (3f)] include carboxyalkyl groups (for example, carboxymethyl groups and other carboxyC groups). 1-6 Alkyl groups, etc.); alkoxycarbonylalkyl groups (e.g., methoxycarbonylmethyl group, ethoxycarbonylmethyl group, etc.) 1-6 Alkoxy-carbonyl-C 1-6 Examples include alkyl groups, halocarbonyl alkyl groups (e.g., chlorocarbonylmethyl group), carboxy-(poly)alkoxy-alkyl groups (e.g., carboxymethoxyethyl group, carboxymethoxyethoxyethyl group), alkoxycarbonyl-(poly)alkoxy-alkyl groups (e.g., methoxycarbonylmethoxyethyl group), halocarbonyl-(poly)alkoxy-alkyl groups (e.g., chlorocarbonylmethoxyethyl group), carboxy-(poly)alkylthio-alkyl groups [e.g., carboxymethylthioethyl group], alkoxycarbonyl-(poly)alkylthio-alkyl groups (e.g., methoxycarbonylmethylthioethyl group), and halocarbonyl-(poly)alkylthio-alkyl groups (e.g., chlorocarbonylmethylthioethyl group).

[0162] A preferred group (3f) is carboxyl C 1-3 Carboxyalkyl groups such as alkyl groups, alkoxycarbonylalkyl groups (for example, C such as methoxycarbonylmethyl group) 1-3 Alkoxy-carbonyl-C 1-3 Alkyl groups, etc.), halocarbonyl alkyl groups (for example, halocarbonyl C such as chlorocarbonylmethyl group) 1-3 Examples include alkyl groups, and more preferably carboxyalkyl groups (for example, carboxymethyl groups and other carboxyC groups). 1-2 (Algorithms, etc.) may also be used.

[0163] R 2 Typical compounds in which (3a) is the group include compounds in which m is 1 to 4 (e.g., 1 or 2, especially 1), n ​​is 1 to 4 (especially 1 to 3), and Ar is a benzene ring or a naphthalene ring, for example mono or tri(hydroxyC) 2-4 Alkylthio)naphthalene, mono or tri(hydroxyC) 2-4 Alkoxy C 2-4 Alkylthio)naphthalene, mono or tri(mercaptoC) 2-4 Alkylthio)naphthalene, mono or tri(mercaptoC) 2-4 Alkylthio C 2-4 Examples include naphthalenthol derivatives such as alkylthio)naphthalene, and benzenethiol derivatives obtained by replacing the naphthalene ring with a benzene ring, corresponding to these naphthalenthol derivatives. Preferred compounds include R 2 Compounds in which the group (3a) is a hydroxyalkyl group, for example mono or tri(hydroxyalkylthio)naphthalene [for example mono or tri(hydroxyethylthio)naphthalene, etc.] 2-3 Naphthalenchiol derivatives such as alkylthionaphthalene may also be used.

[0164] Such compounds can be prepared by reacting aromatic thiol compounds (e.g., naphthalenchiol compounds) with a reaction component selected from alkylene oxides, alkylene carbonates, haloalkanols, alkylene sulfides, alkylene thithiocarbonates, and haloalkanethiols in a solvent such as DMF or DMAc, in the presence of an alkali metal hydroxide base (such as sodium hydroxide). To suppress the formation of disulfide compounds, the reaction may be carried out in the presence of conventional reducing agents and / or polymerization inhibitors.

[0165] R 2 Representative compounds with (3b) as the base include R 3 is linear or branched C 1-4 A compound having an alkyl group, m is 0-4 (e.g., 0-2, especially 0 or 1), n ​​is 1-4 (e.g., 1-3), and Ar is a benzene ring or naphthalene ring, for example, mono or tri(C) 1-4 Alkylthionaphthalene, mono or tri(C) 1-4 Alkoxy C 2-4 Alkylthionaphthalene, mono or tri(C) 1-4 Alkylthio C 2-4 Examples include naphthalenthol derivatives such as alkylthio)naphthalene, and benzenethiol derivatives obtained by replacing the naphthalene ring with a benzene ring, corresponding to these naphthalenthol derivatives. Preferred compounds include R 2 Compounds in which the group (3b) is an alkylthio group or alkylthioalkyl group, for example mono or tri(C) such as mono or tri(methylthio)naphthalene. 1-2 It may also be a naphthalenthol derivative such as alkylthio)naphthalene.

[0166] Such compounds can be prepared by reacting an aromatic thiol compound (e.g., a naphthalenthol compound) with an alkyl halide (e.g., methyl iodide, ethyl iodide) in a solvent such as methylene chloride, DMF, or DMAc, in the presence of an alkali metal hydroxide base (e.g., sodium hydroxide). The reaction may also be carried out in the presence of a conventional reducing agent and / or polymerization inhibitor to suppress the formation of disulfide compounds.

[0167] R 2 Representative compounds with (3c) as the base include A 2 is directly bonded (single bond) or C such as a methylene group 1-3 Alkylene group, R 4 , R 5 and R 6 The compound is a hydrogen atom or a methyl group, m is 0-4 (e.g., 0-2, especially 0 or 1), n ​​is 1-4 (especially 1-3), and Ar is a benzene ring or a naphthalene ring, preferably the group (3c) is a vinyl group or an allyl group. Examples of such compounds include mono or tri(C) 2-4 Alkenylthio)naphthalene, mono or tri(C) 2-3 Alkenyloxy C 2-3 Alkylthionaphthalene, mono or tri(C) 2-3 Alkenilthio C 2-3 Examples include naphthalenthol derivatives such as alkylthio)naphthalene, and benzenethiol derivatives obtained by replacing the naphthalene ring with a benzene ring, corresponding to these naphthalenthol derivatives. Preferred compounds include mono- or tri(vinylthio)naphthalene, mono- or tri(allylthio)naphthalene, mono- or tri(isopropenylthio)naphthalene, and other mono- or tri(C) 2-3 Examples include naphthalenthol derivatives such as alkenylthionaphthalene.

[0168] These compounds are converted in solvents such as methylene chloride, DMF, and DMAc, in the presence of a base such as an alkali metal salt (such as sodium carbonate) and a polymerization inhibitor (such as quinones like methoquinone), into aromatic thiol compounds (e.g., naphthalenchiol compounds) and alkenyl chlorides (such as allyl chloride and isopropenyl chloride). 2-6 It can be prepared by reacting it with a halogenated alkenyl (such as an alkenyl). The solvent may include water.

[0169] R 2 Typical compounds in which group (3d) is a compound in which m is 0 to 4 (e.g., 0 to 2, especially 0 or 1), n ​​is 1 to 4 (especially 1 to 3), and Ar is a benzene ring or a naphthalene ring, preferably in which group (3d) is a (meth)acryloyl group. Examples of such compounds include mono or tri[(meth)acryloyloxy C 2-3 Examples of naphthalenthol derivatives include alkylthio]naphthalene [for example, mono or tri[(meth)acryloylthio]naphthalene, mono or tri[(meth)acryloyloxyethylthio]naphthalene, etc.], and benzenethiol derivatives obtained by replacing the naphthalene ring with a benzene ring, corresponding to these naphthalenthol derivatives. Preferred compounds include naphthalenthol derivatives such as mono or tri(methacryloylthio)naphthalene.

[0170] These compounds can be prepared by reacting an aromatic thiol compound (e.g., a naphthalenchiol compound) with a (meth)acrylate halide (preferably a methacrylate halide) such as (meth)acrylate chloride or (meth)acrylate bromide in a solvent such as methylene chloride, DMF, or DMAc, in the presence of a polymerization inhibitor (such as quinones like methoquinone).

[0171] R 2 Typical compounds with the (3e) group include those where m is 0-4 (e.g., 0-2, especially 0 or 1), and R 7 is a hydrogen atom or a methyl group (especially a hydrogen atom), X 2The compound is an oxygen atom or a sulfur atom (especially an oxygen atom), n is 1 to 4 (especially 1 to 3), and Ar is a benzene ring or a naphthalene ring, preferably the group (3e) is a glycidyl group, glycidyloxy C 2-3 It is an alkyl group compound. Examples of such compounds include mono or tri(glycidyloxy C) 2-3 Examples of naphthalenthol derivatives include alkylthio)naphthalene [e.g., mono- or tri(glycidylthio)naphthalene, mono- or tri(glycidyloxyethylthio)naphthalene, etc.], and benzenethiol derivatives obtained by replacing the naphthalene ring with a benzene ring, corresponding to these naphthalenthol derivatives. Preferred compounds may include naphthalenthol derivatives such as mono- or tri(glycidylthio)naphthalene. Compounds having the (3e) group may be monomers or may include polymers such as dimers to decamers.

[0172] Such compounds can be prepared by reacting an aromatic thiol compound (e.g., a naphthalenchiol compound) with an epihalohydrin such as epichlorohydrin or an epithiohalohydrin such as epithiochlorohydrin, in the presence of a phase-transfer catalyst such as benzyltributylammonium chloride.

[0173] R 2 Typical compounds in which the base (3f) is present include those where m is 0-4 (e.g., 0-2, especially 0 or 1), and A 3 C such as methylene group 1-3 Alkylene group, R 9 is a hydroxyl group or an alkoxy group [-OR 10 ](For example, C such as a methoxy group 1-4 A compound having an alkoxy group, n being 1 to 4 (particularly 1 to 3), and Ar being a benzene ring or naphthalene ring, preferably with group (3f) being a carboxymethyl group or similar carboxyC 1-3 C such as alkyl groups and methoxycarbonylmethyl groups 1-4 Alkoxy-carbonyl-C 1-3It is an alkyl group compound. Examples of such compounds include mono or tri(carboxyl C) 1-3 Alkylthio)naphthalene, mono or tri(carboxyC) 1-3 Alkoxy C 2-3 Alkylthionaphthalene, mono or tri(C) 1-4 Alkoxy-carbonyl-C 1-3 Alkylthionaphthalene, mono or tri(C) 1-4 Alkoxy-carbonyl-C 1-3 Alkoxy C 2-3 Examples of naphthalenthol derivatives include alkylthio)naphthalenes, and corresponding to these naphthalenthol derivatives, benzenethiol derivatives obtained by replacing the naphthalene ring with a benzene ring. Preferred compounds include mono- or tri(carboxymethylthio)naphthalenes. 1-2 It may also be a naphthalenthol derivative such as alkylthio)naphthalene.

[0174] Such compounds include aromatic thiol compounds (e.g., naphthalenthol compounds) and alkyl haloalkanoates (e.g., chloroethyl acetate, etc.). 1-3 Alkanic Acid C 1-4 It can be prepared by reacting alkyl groups (and other elements) in a solvent such as water, in the presence of a base such as an alkali metal hydroxide (such as sodium hydroxide). To suppress the formation of disulfide compounds, the reaction may be carried out in the presence of conventional reducing agents and / or polymerization inhibitors.

[0175] Of these aromatic thiol derivatives, those having reactive groups such as hydroxyalkyl groups and carboxyalkyl groups can be effectively used as monomers for polymers, derivatives having polymerizable groups such as (meth)acryloyl groups and glycidyl groups are useful for forming curable resins or their compositions, and derivatives having alkyl groups are useful as resin additives (refractive index improvers, etc.) added to resins. [Examples]

[0176] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The evaluation method is shown below.

[0177] [Evaluation Method] ( 1 (H-NMR) Measurements were performed using JEOL Ltd.'s "JNM-ECZ400 (400MHz)" and "JNM-ECA600 (600MHz)," with chloroform-d (CDCl3) as the deuterated solvent and tetramethylsilane (TMS) as the standard substance.

[0178] (Melting point) The melting point was measured using a melting point measuring device (Büch 535) in accordance with JIS K 4101 (1993) [5.1 Visual method].

[0179] (5% weight loss temperature) Using a differential thermogravimetric analyzer (TG / DTA6200, manufactured by Seiko Instruments Inc.), the temperature was increased from 25 to 450°C at a heating rate of 10°C / min under a nitrogen gas atmosphere (50 mL / min), and the temperature at which the weight decreased by 5% was measured.

[0180] (Refractive index) The sample was dissolved in 1,3-dimethyl-2-imidazolidinone (DMI) to prepare several solutions of different concentrations. The refractive index of each solution was measured at a temperature of 25°C and a wavelength of 589 nm using an Abbe refractometer (NAR-1T, manufactured by Atago Co., Ltd.). The refractive index was determined by extrapolating the obtained refractive index results at each concentration to 100% by mass.

[0181] (Acetonitrile soluble) 100 mg of the sample and 100 mL of acetonitrile were placed in a 100 mL container, and the mixture was stirred for 1 to 15 minutes using an ultrasonic cleaner (frequency 40 kHz) at a temperature of 10 to 30°C to prepare a mixture (concentration equivalent to approximately 0.13% by mass). The presence or absence of turbidity in the resulting mixture was visually checked.

[0182] (HPLC purity, disulfide content) The area percentage of the HPLC measured under the following conditions was used as the HPLC purity and disulfide content (dimer content) of the aromatic thiol compound. When the disulfide content was below the detection limit, it was indicated as "ND".

[0183] HPLC system: Shimadzu Corporation "LC-20A" Column: YMC-Triart C18 (5μm, 4.6mmφ × 150mm) Mobile phase: 5% phosphoric acid aqueous solution / acetonitrile (acetonitrile 65% → 90% Flow rate: 1.0 mL / min, Column temperature: 40°C, Detection wavelength: UV 210 nm.

[0184] (content) The content (absolute purity) of the sample was calculated using the following formula, based on the results obtained by measuring a standard corresponding to the target sample [an aromatic thiol compound free of impurities (100% content)] under the same measurement conditions as described above (HPLC purity, disulfide content), and the results obtained by measuring the HPLC purity of the target sample.

[0185] Content [mass%] = (HPLC sample weight of standard ÷ HPLC area value of standard) ÷ (HPLC sample weight of target sample ÷ HPLC area value derived from aromatic thiol compounds in the target sample) × 100.

[0186] [Example 1] (Synthesis of 1,6-naphthalenedithiol)

[0187] [ka]

[0188] Under a nitrogen atmosphere, 100 g (300.9 mmol) of disodium 1,6-naphthalenedisulfonate, 451 g of toluene, 8.8 g (0.4 mol ratio) of N,N-dimethylformamide, and 89.6 g (2.5 mol ratio) of thionyl chloride were charged into a 1000 mL flask. The mixture was heated to 100°C and reacted at 97-102°C for 8 hours. After the reaction, the mixture was cooled to 30°C, 451 g of water was added at 20-30°C, and the mixture was stirred for at least 10 minutes. The lower aqueous phase was separated and removed. 451 g of water was added to the organic phase in the same manner as above, and the mixture was stirred for at least 10 minutes and separated to obtain 622.5 g of 1,6-naphthalenedisulfonyl chloride (16NDSC) toluene solution as the organic phase (yield: 97 mol%, HPLC purity: 98%).

[0189] Under a nitrogen atmosphere, 1800 g of toluene and 1439.8 g of 36% hydrochloric acid (48.8 mol ratio) were charged into a 5000 mL flask and heated to 60°C. After heating, 622.5 g (291.0 mmol) of the 16NDSC toluene solution and 258.8 g (13.6 mol ratio) of zinc powder were added in portions over 3 hours and 30 minutes at a temperature of 60-70°C, and the mixture was reacted at the same temperature for 1 hour. After the reaction, the mixture was cooled to 30°C, allowed to stand at 0-30°C, and the lower aqueous phase was separated and removed. The organic phase was then filtered, and the residue was washed with 33 g of toluene. The obtained filtrate was desolvated and dried under reduced pressure at 45°C or below to obtain 50.5 g of 1,6-naphthalenedithiol (1,6-isomer or 16NDSH) in solid form (yield: 90 mol%, acetonitrile solubility: clear, content: 99.2% by mass, HPLC purity: 99.8%, disulfide content: 0.2%).

[0190] (Purification of 1,6-body) Under a nitrogen atmosphere, 10.0 g (52.0 mmol) of 16NDSH (1,6-isomer), 58.2 g (2.8 mol ratio) of a 10% by mass aqueous sodium hydroxide solution, and 0.10 g (0.05 mol ratio) of sodium borohydride were charged into a 100 mL flask, and the temperature was raised to 60 °C. After the temperature was raised, the mixture was stirred at 60 - 70 °C for 1 hour or more and then cooled to 30 °C. Under a nitrogen atmosphere, after filtration at 20 - 30 °C, the residue was washed with 5.0 g of water. To the obtained filtrate, 15.8 g (3.00 mol ratio) of 36% by mass hydrochloric acid was added dropwise over 1 hour or more at 20 - 30 °C under a nitrogen atmosphere. After stirring for 30 minutes, the mixture was filtered. The obtained wet crystals were washed with 248 g (4769 g / mol) of ion-exchanged water and dried to obtain 9.8 g of 16NDSH (1,6-isomer) as a solid (yield: 96 mol%, acetonitrile solution state: no turbidity, content: 100.0% by mass, HPLC purity: 100.0%, disulfide-containing body content: 0.1% or less).

[0191] Melting point: 35 - 36 °C 5% weight loss temperature: 171 °C Refractive index: 1.722 1 1H-NMR (CDCl3): δ (ppm) 3.57 (s, 1H), 3.61 (s, 1H), 7.31 (dd, J 8.4 7.4, 1H), 7.40 (dd, J 9.0 1.8, 1H), 7.48 (d, J 7.2, 1H), 7.55 (d, J 8. 4, 1H), 7.72 (d, J 1.8, 1H), 8.03 (d, J 9.0, 1H).

[0192] The evaluation results before and after purification of 16NDSH obtained in Example 1 are shown in the following table.

[0193]

Table 1

[0195] [[ID= 30]] [Comparative Example 1-1] Crystallization from 1,6-methanol In a 1 L flask, 25.0 g of 16NDSH (acetonitrile soluble state: clear, content: 97.6% by mass, HPLC purity: 98.9%, disulfide content: 1.1%) synthesized in the same manner as in Example 1 (synthesis of 1,6-naphthalenedithiol) and 250.0 g of methanol were charged and stirred at 25°C to dissolve. The solution was cooled to below 5°C, 44.1 g of water was added dropwise to precipitate crystals, and 18.1 g of a yellow solid was obtained by filtration (yield: 71 mol%, acetonitrile soluble state: clear, content: 95.9% by mass, HPLC purity: 99.3%, disulfide content: 0.7%).

[0196] [Comparative Examples 1-2] Crystallization from 1,6-heptane In a 1L flask, 20.0g of 16NDSH (acetonitrile soluble state: clear, content: 97.6% by mass, HPLC purity: 98.9%, disulfide content: 1.1%) synthesized in the same manner as in Example 1 (synthesis of 1,6-naphthalenedithiol) and 229.5g of heptane were charged, and the temperature was raised to 98°C and stirred. After stirring, the mixture was slowly cooled to below 5°C to precipitate crystals, and 7.9g of a yellow solid was obtained by filtration (yield: 40 mol%, acetonitrile soluble state: clear, content: 97.3% by mass, HPLC purity: 98.9%, disulfide content: 1.1%).

[0197] The obtained yellow solid (7.9 g) and heptane (90.9 g) were charged together, and the mixture was heated to 98°C and stirred. After stirring, it was slowly cooled to 5°C to precipitate crystals, and 5.9 g of the yellow solid was obtained by filtration (yield: 30 mol%, acetonitrile solubility: clear, content: 98.5% by mass, HPLC purity: 98.9%, disulfide content: 1.1%).

[0198] Thus, although the crystallization process from heptane was performed twice, a sufficiently high-purity 1,6-isomer could not be obtained, and the yield decreased significantly.

[0199] [Comparative Examples 1-3] 1,6-isomer silica gel chromatography purification 20.0 g of 16NDSH (acetonitrile soluble state: clear, content: 97.6% by mass, HPLC purity: 98.9%, disulfide content: 1.1%), synthesized in the same manner as in Example 1 (synthesis of 1,6-naphthalenedithiol), was separated and purified by silica gel column chromatography (ethyl acetate / heptane (volume ratio) = 1 / 32) to obtain 14.2 g of 16NDSH as a pale yellow solid (yield: 72 mol%, acetonitrile soluble state: clear, content: 97.2% by mass, HPLC purity: 99.6%, disulfide content: 0.3%).

[0200] The obtained solid was separated and purified again by silica gel column chromatography (ethyl acetate / heptane (volume ratio) = 1 / 32) to obtain 10.0 g of 16NDSH as a pale yellow solid (yield: 50 mol%, acetonitrile solubility: clear, content: 98.5% by mass, HPLC purity: 99.5%, disulfide content: 0.3%).

[0201] Thus, even after two purification steps using chromatography, the improvement in purity and the reduction in the content of disulfide compounds were insufficient, and the yield decreased significantly.

[0202] [Comparative Example 1-4] Adsorption Treatment Under a nitrogen atmosphere, 250 g of methanol (10 times the amount of 16NDSH) and 25 g of 16NDSH (acetonitrile solubility: clear, content: 97.6% by mass, HPLC purity: 100.0%, disulfide content: "ND") synthesized in the same manner as in Example 1 (synthesis of 1,6-naphthalenedithiol) were charged into a 1 L flask, and the temperature was raised to 30°C. The mixture was stirred for more than 10 minutes to confirm complete dissolution. To the obtained solution, 2.5 g of activated carbon (Shirasagi A, manufactured by Osaka Gas Chemical Co., Ltd.) (10% by mass relative to 16NDSH) was added, and after stirring for 30 minutes, the solution was filtered, and the residue was washed with methanol to obtain 280.2 g of 16NDSH solution A (acetonitrile solubility: no turbidity, HPLC purity: 99.0%, disulfide content: 1.0%). To the obtained 16NDSH solution A, 2.5 g of acid clay (Mizuka Life F-1G, manufactured by Mizusawa Chemical Industry Co., Ltd.) (10% by mass relative to 16NDSH) was added, and after stirring for 30 minutes or more, The solution was filtered, and the residue was washed with methanol to obtain 282.2 g of 16NDSH solution B (acetonitrile solubility: no turbidity, HPLC purity: 98.5%, disulfide content: 1.5%). To the obtained 16NDSH solution B, 2.5 g of the acid clay (10% by mass relative to 16NDSH) was added again, and after stirring for 30 minutes or more, the solution was filtered, and the residue was washed with methanol to obtain 282.2 g of 16NDSH solution C (acetonitrile solubility: no turbidity, HPLC purity: 98.4%, disulfide content: 1.6%).

[0203] Thus, even after decolorization with activated carbon and acid clay, the purity could not be sufficiently improved, and the content of disulfide compounds increased significantly.

[0204] [Reference Example 1-1] Distillation of 1,6-forms 16NDSH (in acetonitrile solution: no turbidity, content: 97.0% by mass, HPLC purity: 98.3%, disulfide content: 1.4%) synthesized in the same manner as in (Synthesis of 1,6-naphthalenedithiol) of Example 1, 148 g, was charged into a distillation apparatus (simple distillation apparatus), and distilled at an internal temperature of 162 to 167 °C and a pressure of 0.6 hPa to obtain 144 g of a colorless fraction distilled at a top temperature of 141 to 146 °C (yield: 97 mol%, in acetonitrile solution: no turbidity, content: 99.8% by mass, HPLC purity: 100.0%, disulfide content: "N.D.").

[0205] [Reference Example 1-2 to 1-6] Distillation was carried out in the same manner as in the distillation operation of Reference Example 1-1, except that distillation was carried out under the following conditions to obtain 16NDSH. All of the obtained 16NDSH had the following properties: in acetonitrile solution: no turbidity, content: 99.8% by mass, HPLC purity: 100.0%, disulfide content: "N.D.".

[0206] Reference Example 1-2: Internal temperature 167 °C, pressure 1 hPa, and top temperature 146 °C Reference Example 1-3: Internal temperature 200 °C, pressure 10 hPa, and top temperature 181 °C Reference Example 1-4: Internal temperature 208 °C, pressure 15 hPa, and top temperature 187 °C Reference Example 1-5: Internal temperature 218 °C, pressure 20 hPa, and top temperature 194 °C Reference Example 1-6: Internal temperature 234 °C, pressure 30 hPa, and top temperature 211 °C [Example 2] (Synthesis of 1,5-naphthalenedithiol)

[0207] [Chemical formula]

[0208] Under a nitrogen atmosphere, 100 g (300.9 mmol) of disodium 1,5-naphthalenedisulfonate, 2003 g of toluene, 8.8 g (0.4 mol ratio) of N,N-dimethylformamide, and 85.9 g (2.4 mol ratio) of thionyl chloride were charged into a 5 L flask and heated to 100°C. The temperature after heating was 97-102°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 5 hours. After the reaction, the mixture was cooled to 30°C, 451 g of water was added at 20-30°C, and the mixture was stirred for more than 10 minutes. The lower aqueous phase was separated and removed. Similarly, 150 g of water was added to the obtained organic phase and the mixture was stirred for more than 10 minutes, and the organic phase was separated. This organic phase was filtered, and the residue was washed with 30 g of toluene to obtain 2141.6 g of 1,5-naphthalenedisulfonyl chloride (15NDSC) toluene solution (yield: 96 mol%, HPLC purity: 96%).

[0209] Under a nitrogen atmosphere, 580 g of toluene and 1422.1 g of 36% by mass hydrochloric acid (48.4 mol ratio) were charged into a 10 L flask and heated to 60°C. After heating, 2141.6 g (289.8 mmol) of the 15NDSC toluene solution and 257.7 g (13.6 mol ratio) of zinc powder were added in portions over 1 hour and 30 minutes. The temperature during addition was 60-70°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 1 hour. After the reaction, the mixture was cooled to 30°C, allowed to stand at 0-30°C, and the lower aqueous phase was separated and removed. The organic phase was then filtered, and the residue was washed with 188 g of toluene. The obtained filtrate was desolvated and dried under reduced pressure at 40°C or below to obtain 58.5 g of 1,5-naphthalenedithiol (1,5-isomer or 15NDSH) in solid form (yield: 99 mol%, acetonitrile solubility: turbid, content: 98.4% by mass, HPLC purity: 100.0%, disulfide content: 0.1% or less).

[0210] (Purification of 1,5-body) Under a nitrogen atmosphere, 10.0 g (52.0 mmol) of 15NDSH (1,5-isomer), 45.8 g (2.2 mol ratio) of 10% by mass sodium hydroxide aqueous solution, and 0.10 g (0.05 mol ratio) of sodium borohydride were charged into a 100 mL flask and heated to 60°C. After heating, the mixture was stirred at 60-70°C for more than 1 hour and then cooled to 30°C. Under a nitrogen atmosphere, the mixture was filtered at 20-30°C, and the residue was washed with 5.0 g of water. To the resulting filtrate, 13.5 g (2.56 mol ratio) of 36% by mass hydrochloric acid was added dropwise over more than 1 hour under a nitrogen atmosphere at 20-30°C, stirred for 30 minutes, and then filtered. The obtained wet crystals were washed with 248 g of deionized water and dried to obtain 9.8 g of 15NDSH (1,5-isomer) in solid form (yield: 98 mol%, acetonitrile solubility: clear, content: 100.0 mass%, HPLC purity: 100.0%, disulfide content: 0.1% or less).

[0211] Melting point: 120~121℃ 5% weight loss temperature: 176℃ Refractive index: 1.711 1 H-NMR (CDCl3): δ(ppm) 3.62(s,2H), 7.40(dd,J 8.4 7.2,2H), 7.59(d,J 7.2,2H), 8.04(d,J 8.4,2H).

[0212] The table below shows the evaluation results of 15NDSH obtained in Example 2 before and after purification.

[0213] [Table 2]

[0214] As is clear from the results in Table 2, the 1,5-isomer could be purified to a high level using a simple method without increasing the number of disulfide compounds, and the yield was also high.

[0215] [Reference Example 2] Distillation of 1,5-body 10g of 15NDSH (1,5-isomer) was charged into a distillation apparatus (simple distillation apparatus) and distilled, and a fraction with a boiling point of 150°C / 0.6hPa was distilled out. However, crystallization occurred inside the condenser (melting point of the 1,5-isomer is 120°C), blocking the distillation line, so the process was stopped.

[0216] [Example 3] (Synthesis of 2,6-naphthalenedithiol)

[0217] [ka]

[0218] Under a nitrogen atmosphere, 100 g (300.9 mmol) of disodium 2,6-naphthalenedisulfonate, 451 g of toluene, 8.8 g (0.4 mol ratio) of N,N-dimethylformamide, and 100.3 g (2.8 mol ratio) of thionyl chloride were charged into a 1 L flask and heated to 100°C. The temperature after heating was 97-102°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 8 hours. After the reaction, the mixture was cooled to 30°C, 226 g of water was added at 20-30°C, and the mixture was stirred for more than 2 hours before being filtered. The resulting wet crystals were washed with 60 g of toluene and dried to obtain 92.6 g of solid 2,6-naphthalenedisulfonyl chloride (26NDSC) (yield: 93 mol%, HPLC purity: 98%).

[0219] Under a nitrogen atmosphere, 4478g of toluene and 249.0g of zinc powder (13.6 mol ratio) were charged into a 10L flask and heated to 60°C. After heating, 92.6g of 26NDSC (279.9 mmol) and 692.4g of 36% by mass hydrochloric acid (24.4 mol ratio) were added in installments over 1 hour. The temperature during addition was 60-70°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 2 hours. After the reaction, the mixture was filtered, and the residue was washed with 55g of toluene that had been preheated to 60°C. The obtained filtrate was separated at 55-60°C, and the lower aqueous phase was removed. Then, 221g of water and 21.0g of 36% by mass hydrochloric acid (0.74 mol ratio) were charged into the obtained organic phase and heated to 50°C. The temperature after heating was 50-60°C, and the mixture was kept at this temperature in a constant temperature bath and stirred for 30 minutes, after which the lower aqueous phase was separated. The obtained organic phase was desolvated to 398g by reduced pressure at a temperature below 60°C and cooled to 5°C. The temperature after cooling was 0-5°C, and the mixture was kept at this temperature in a constant temperature bath and stirred for 1 hour, after which it was filtered. The obtained wet crystals were washed with 55g of water and dried to obtain 40.2g of 2,6-naphthalenedithiol (2,6-isomer or 26NDSH) in solid form (yield: 75 mol%, acetonitrile solubility: turbid, content: 96.7% by mass, HPLC purity: 98.9%, disulfide content: 0.5%).

[0220] (Purification of 2,6-body) Under a nitrogen atmosphere, 10.0 g (52.0 mmol) of 26NDSH (2,6-isomer), 45.8 g (2.2 mol ratio) of 10% by mass sodium hydroxide aqueous solution, and 0.10 g (0.05 mol ratio) of sodium borohydride were charged into a 100 mL flask and heated to 60°C. After heating, the mixture was stirred at 60-70°C for more than 1 hour and then cooled to 30°C. Under a nitrogen atmosphere, the mixture was filtered at 20-30°C, and the residue was washed with 5.0 g of water. To the resulting filtrate, 13.5 g (2.56 mol ratio) of 36% by mass hydrochloric acid was added dropwise over more than 1 hour under a nitrogen atmosphere at 20-30°C, stirred for 30 minutes, and then filtered. The obtained wet crystals were washed with 248 g of deionized water and dried to obtain 9.8 g of 26NDSH (2,6-isomer) in solid form (yield: 98 mol%, acetonitrile solubility: clear, content: 99.8% by mass, HPLC purity: 99.8%, disulfide content: 0.2%).

[0221] Melting point: 196~197℃ 5% weight loss temperature: 187℃ Refractive index: 1.718 1 H-NMR (CDCl3): δ(ppm) 3.58(s,2H), 7.32(dd,J 8.0 1.6,2H), 7.57(d,J 8.0,2H), 7.68(d,J 1.6,2H).

[0222] The table below shows the evaluation results of 26NDSH obtained in Example 3 before and after purification.

[0223] [Table 3]

[0224] As is clear from the results in Table 3, the 2,6-isomer could be purified to a high level using a simple method without increasing (or even reducing) the disulfide compound, and the yield was also high.

[0225] [Reference Example 3] Distillation of 2,6-body When 24g of 26NDSH (2,6-isomer) was charged into a distillation apparatus (single distillation apparatus) and distillation was performed, sublimation began at 145℃ / 0.7hPa (melting point of 2,6-isomer: 196~197℃), and the distillation line became blocked, so the distillation operation was stopped.

[0226] [Example 4] (Synthesis of 2,7-naphthalenedithiol)

[0227] [ka]

[0228] Under a nitrogen atmosphere, 100 g (300.9 mmol) of disodium 2,7-naphthalenedisulfonate, 632 g of toluene, 8.8 g (0.4 mol ratio) of N,N-dimethylformamide, and 89.5 g (2.5 mol ratio) of thionyl chloride were charged into a 1 L flask and heated to 100°C. The temperature after heating was 97-102°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 3 hours. After the reaction, the mixture was cooled to 30°C, 451 g of water was added at 20-30°C, and the mixture was stirred for more than 10 minutes. The lower aqueous phase was separated and removed. Similarly, 451 g of water was added to the obtained organic phase and stirred for more than 10 minutes, followed by separation to obtain 738.6 g of 2,7-naphthalenedisulfonyl chloride (27NDSC) toluene solution as the organic phase (yield: 99 mol%, HPLC purity: 99%).

[0229] Under a nitrogen atmosphere, 6507 g of toluene and 1264.3 g of 36% hydrochloric acid (41.9 mol ratio) were charged into a 10 L flask and heated to 60°C. After heating, 738.6 g (297.6 mmol) of 27NDSC toluene solution and 264.7 g (13.6 mol ratio) of zinc powder were added in installments over 3 hours and 30 minutes. The temperature during addition was 60-70°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 1 hour. After the reaction, the mixture was cooled to 30°C, allowed to stand at 0-30°C, and the lower aqueous phase was separated and removed. The organic phase was then filtered, and the residue was washed with 75 g of toluene. The resulting filtrate was desolvated under reduced pressure at 55°C or below until it weighed 203 g, and then filtered. The obtained wet crystals were washed with 59 g of toluene and dried to obtain 43.1 g of 2,7-naphthalenedithiol (2,7-isomer or 27NDSH) in solid form (yield: 75 mol%, acetonitrile solubility: turbid, content: 89.1% by mass, HPLC purity: 99.2%, disulfide content: 0.4%).

[0230] (2,7-body purification) Under a nitrogen atmosphere, 111.6 g (517.1 mmol) of 27NDSH (2,7-isomer), 581.9 g (2.8 mol ratio) of 10% by mass sodium hydroxide aqueous solution, and 1.0 g (0.05 mol ratio) of sodium borohydride were charged into a 1 L flask and heated to 60°C. After heating, the mixture was stirred at 60-70°C for more than 1 hour and then cooled to 30°C. Under a nitrogen atmosphere, the mixture was filtered at 20-30°C, and the residue was washed with 157 g of water. To the obtained filtrate, 73.3 g (1.40 mol ratio) of 36% by mass hydrochloric acid was added dropwise at 30-40°C under a nitrogen atmosphere and stirred for 30 minutes. Then, 77.5 g (1.48 mol ratio) of 36% by mass hydrochloric acid was added dropwise, stirred for another 30 minutes, and then filtered. The obtained wet crystals were washed with 1991 g of deionized water and dried to obtain 88.4 g of 27NDSH (2,7-isomer) in solid form (yield: 88 mol%, acetonitrile solubility: clear, content: 98.9% by mass, HPLC purity: 99.5%, disulfide content: 0.3%).

[0231] Melting point: 186~188℃ 5% weight loss temperature: 184℃ Refractive index: 1.721 1 H-NMR (CDCl3): δ(ppm)3.60(s,2H), 7.27(dd,J 8.4 1.2,2H), 7.58(d,J 1.2,2H), 7.64(d,J 8.4,2H).

[0232] The table below shows the evaluation results of 27NDSH obtained in Example 4 before and after purification.

[0233] [Table 4]

[0234] As is clear from the results in Table 4, the 2,7-isomer could be purified to a high level using a simple method without increasing (or even reducing) the disulfide compound, and the yield was also high.

[0235] [Reference Example 4] Distillation of 2,7-body [Distillation operation] When 20g of 27NDSH (2,7-isomer) was charged into the distillation apparatus and distillation was performed, sublimation began at 145℃ / 0.7hPa (melting point of 2,7-isomer: 186~188℃), and the distillation line became blocked, so the distillation operation was stopped.

[0236] [Example 5] (Synthesis of 1-naphthalenthol)

[0237] [ka]

[0238] Under a nitrogen atmosphere, 30.7 g (133.4 mmol) of sodium 1-naphthalenesulfonate, 180 g of toluene, 3.3 g (0.3 mol ratio) of N,N-dimethylformamide, and 33.9 g (2.13 mol ratio) of thionyl chloride were charged into a 300 mL flask and heated to 100°C. The temperature after heating was 97-102°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 3 hours. After the reaction, the mixture was cooled to 30°C, 75 g of water was added at 20-30°C, and the mixture was stirred for at least 10 minutes. The lower aqueous phase was separated and removed. 75 g of water was added to the organic phase in the same manner as above, and the mixture was stirred for at least 10 minutes and separated to obtain 202.2 g of 1-naphthalenesulfonyl chloride (1NSC) toluene solution as the organic phase (yield: 95 mol%, HPLC purity: 80%).

[0239] Under a nitrogen atmosphere, 153.9 g (12.0 mol ratio) of 36% by mass hydrochloric acid was charged into a 500 mL flask and heated to 40°C. After heating, 202.2 g (126.6 mmol) of the aforementioned 1NSC toluene solution and 33.1 g (4.0 mol ratio) of zinc powder were added in installments over 3 hours at a temperature of 40-50°C, and the temperature was raised to 65°C. The reaction was carried out at a temperature of 65-75°C for 1 hour. After the reaction, the mixture was cooled to 30°C, allowed to stand at 0-30°C, and the lower aqueous phase was separated and removed. The organic phase was then filtered, and the residue was washed with 15 g of toluene. The obtained filtrate was desolvated and dried under reduced pressure at 60°C or below to obtain 19.0 g of 1-naphthalenchiol (1-isomer or 1NSH) in liquid form (yield: 94 mol%, acetonitrile solubility: clear, content: 98.0% by mass, HPLC purity: 98.5%, disulfide content: 0.1% or less).

[0240] (1-body purification) Under a nitrogen atmosphere, 10.0 g (62.4 mmol) of 1 NSH (1-isomer), 37.4 g (1.5 mol ratio) of 10% by mass sodium hydroxide aqueous solution, and 0.13 g (0.05 mol ratio) of sodium borohydride were charged into a 100 mL flask. The mixture was stirred at 20-30°C for at least 1 hour, filtered under a nitrogen atmosphere at 20-30°C, and the residue was washed with 157 g of water. To the obtained filtrate, 10.6 g (1.68 mol ratio) of 36% by mass hydrochloric acid was added dropwise over more than 1 hour under a nitrogen atmosphere at 20-30°C. After stirring for 30 minutes, the upper aqueous phase was separated and removed, and the resulting organic phase was dried to obtain 9.7 g of 1 NSH (1-isomer) in liquid form (yield: 97 mol%, acetonitrile solubility: clear, content: 98.9% by mass, HPLC purity: 98.9%, disulfide content: 0.1% or less).

[0241] Melting point: 15℃ Refractive index: 1.679

[0242] The table below shows the evaluation results of 1NSH obtained in Example 5 before and after purification.

[0243] [Table 5]

[0244] As is clear from the results in Table 5, the 1-isomer could be purified to a high level using a simple method without increasing the number of disulfide compounds, and the yield was also high.

[0245] [Example 6] (Synthesis of 2-naphthalenthol)

[0246] [ka]

[0247] Under a nitrogen atmosphere, 418.7 g (1818.8 mmol) of sodium 2-naphthalenesulfonate, 1580 g of toluene, 39.9 g (0.3 mol ratio) of N,N-dimethylformamide, and 246.7 g (1.14 mol ratio) of thionyl chloride were charged into a 5000 mL flask and heated to 100°C. The temperature after heating was 97-102°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 5 hours. After the reaction, the mixture was cooled to 30°C, 545 g of water was added at 20-30°C, and the mixture was stirred for more than 10 minutes. The lower aqueous phase was separated and removed. 545 g of water was added to the organic phase in the same manner as above, and the mixture was stirred for more than 10 minutes and separated to obtain 1946 g of 2-naphthalenesulfonyl chloride (2NSC) toluene solution as the organic phase (yield: 98 mol%, HPLC purity: 99%).

[0248] Under a nitrogen atmosphere, 550.1 g (12.0 mol ratio) of 36% by mass hydrochloric acid was charged into a 2000 mL flask and heated to 55°C. After heating, 493 g (452.1 mmol) of the 2NSC toluene solution and 112.3 g (3.8 mol ratio) of zinc powder were added in installments over 2 hours at a temperature of 55-70°C, and the temperature was raised to 65°C. The mixture was reacted at 60-70°C for 1 hour. After the reaction, the mixture was cooled to 30°C, allowed to stand at 0-30°C, and the lower aqueous phase was removed by liquid-liquid extraction. The organic phase was then filtered, and the residue was washed with 45 g of toluene. The resulting filtrate was desolvated under reduced pressure below 60°C until it reached 89 g, and 115 g of methanol was added dropwise at 60-65°C for 1 hour, and the mixture was cooled to 20°C. The mixture was then filtered. The obtained wet crystals were washed with 70 g of methanol and dried to obtain 59.7 g of 2-naphthalenchiol (2-isomer or 2NSH) in solid form (yield: 82 mol%, acetonitrile solubility: turbid, content: 96.0 mass%, HPLC purity: 99.4%, disulfide content: 0.3%).

[0249] (2-form purification) Under a nitrogen atmosphere, 10.0 g (62.4 mmol) of 2NSH(2-isomer), 37.4 g (1.5 mol ratio) of 10% by mass sodium hydroxide aqueous solution, and 0.13 g (0.05 mol ratio) of sodium borohydride were charged into a 100 mL flask and heated to 60°C. After heating, the mixture was stirred at 60-70°C for more than 1 hour and then cooled to 30°C. Under a nitrogen atmosphere, the mixture was filtered at 20-30°C, and the residue was washed with 157 g of water. To the obtained filtrate, 10.8 g (1.70 mol ratio) of 36% by mass hydrochloric acid was added dropwise over more than 1 hour under a nitrogen atmosphere at 20-30°C, stirred for 30 minutes, and then filtered. The obtained wet crystals were washed with 248 g of deionized water and dried to obtain 9.7 g of 2NSH(2-isomer) in solid form (yield: 97 mol%, acetonitrile solubility: clear, content: 99.4% by mass, HPLC purity: 99.4%, disulfide content: 0.3%).

[0250] Melting point: 81-82°C 5% weight loss temperature: 134℃ Refractive index: 1.685

[0251] The table below shows the evaluation results of 2NSH obtained in Example 6 before and after purification.

[0252] [Table 6]

[0253] As is clear from the results in Table 6, the 2-isomer could be purified to a high level using a simple method without increasing the number of disulfide compounds, and the yield was also high.

[0254] [Example 7] (Synthesis of 1,3,6-naphthalenethiol)

[0255] [ka]

[0256] Under a nitrogen atmosphere, 100 g (230.3 mmol) of trisodium 1,3,6-naphthalenethrisulfonate, 921 g of toluene, 6.7 g (0.4 mol ratio) of N,N-dimethylformamide, and 90.4 g (3.3 mol ratio) of thionyl chloride were charged into a 1 L flask and heated to 100°C. The temperature after heating was 97-102°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 2 hours. After the reaction, the mixture was cooled to 30°C, 239 g of water was added at 20-30°C, and the mixture was stirred for more than 10 minutes. The lower aqueous phase was separated and removed. Similarly, 239 g of water was added to the obtained organic phase and stirred for more than 10 minutes. The aqueous phase was removed by liquid-liquid extraction to obtain 991.8 g of 1,3,6-naphthalenethrisulfonyl chloride (136NTSC) toluene solution as the organic phase (yield: 93 mol%, purity by HPLC: 95%).

[0257] Under a nitrogen atmosphere, 400 g of toluene and 651.5 g of 36% by mass hydrochloric acid (30.0 mol ratio) were placed in a 3000 mL flask and heated to 60°C. After heating, 991.8 g (214.2 mmol) of the 136 NTSC toluene solution and 168.1 g (12.0 mol ratio) of zinc powder were added in portions over 3 hours and 30 minutes. The temperature during addition was 60-70°C, and the mixture was kept at this temperature in a constant temperature bath and reacted for 1 hour. After the reaction, it was cooled to 30°C, allowed to stand at 0-30°C, and the lower aqueous phase was separated and removed. Subsequently, the organic phase was filtered, and the residue was washed with 43 g of toluene. The obtained filtrate was desolvated and dried under reduced pressure at 40°C or below to obtain 29.5 g of 1,3,6-naphthalenthiol (1,3,6-isomer or 136NTSH) in solid form (acetonitrile solubility: clear, content: 99.0% by mass, HPLC purity: 100.0%, disulfide content: 0.1% or less).

[0258] (Purification of 1, 3, 6-body structures) Under a nitrogen atmosphere, 10.0 g (44.6 mmol) of 136 NTSH (1,3,6-isomer), 53.5 g (3.0 mol ratio) of 10% by mass sodium hydroxide aqueous solution, and 0.16 g (0.1 mol ratio) of sodium borohydride were charged into a 100 mL flask and heated to 60°C. After heating, the mixture was stirred at 60-70°C for more than 1 hour and then cooled to 30°C. Under a nitrogen atmosphere, the mixture was filtered at 20-30°C, and the residue was washed with 5.0 g of water. To the resulting filtrate, 18.1 g (4.0 mol ratio) of 36% by mass hydrochloric acid was added dropwise over more than 1 hour at 20-30°C under a nitrogen atmosphere, stirred for 30 minutes, and then filtered. The obtained wet crystals were washed with 250 g of deionized water and dried to obtain 9.8 g of 136NTSH (1,3,6-isomer) in solid form (yield: 98 mol%, acetonitrile solubility: clear, content: 100.0% by mass, HPLC purity: 100.0%, disulfide content: 0.1% or less).

[0259] Melting point: 84-86℃ 5% weight loss temperature: 215℃ Refractive index: 1.764 1H-NMR (CDCl3): δ(ppm)3.54(s,1H), 3.55(s,1H), 3.57(s,1H), 7.34(dd,J 2.0 1.6,1H), 7.36(d,J 1,6,1H), 7.43(s,1H), 7.55(d,J 2.0,1H), 7.93(d,J 8.8,1H).

[0260] The table below shows the evaluation results of 136NTSH obtained in Example 7 before and after purification.

[0261] [Table 7]

[0262] As is clear from the results in Table 7, the 1,3,6-isomer could be purified to a high level using a simple method without increasing the number of disulfide compounds, and the yield was also high. [Industrial applicability]

[0263] Aromatic thiol compounds (e.g., naphthalenchiol compounds) obtained by the purification method of the present invention are of high purity and possess aromatic ring skeletons such as benzene ring skeletons and naphthalene ring skeletons, thus exhibiting high refractive index and high heat resistance, and can be used in a variety of applications. Therefore, aromatic thiol compounds or their derivatives can be used, for example, as raw materials or reaction intermediates for reagents and functional compounds, optical materials [e.g., display materials such as anti-reflective coatings (e.g., index matching films), optical adhesives or sealants, etc.], additives [or resin additives, e.g., refractive index improvers, fluorescent quenchers, crosslinking agents or crosslinking aids, epoxy resin curing agents or curing accelerators, chain transfer agents, etc.], electrical and electronic materials (resist materials such as resist underlayer films, organic semiconductor materials, etc.), coating materials or paints (coating compositions for forming hard coat layers, etc.), adhesives or sealants, etc.

[0264] The raw materials or reaction intermediates can be, for example, resin raw materials or monomer components (for example, monomer components with a high refractive index). The resins that can be prepared from the resin raw materials or monomer components may be thermoplastic resins [for example, polyester resins (polyester resin, polyester carbonate resin, polycarbonate resin, polythioester resin, etc.), polyether resins, polysulfide resins (polyadditives by enthiol reaction, etc.), polyurethane resins (polyurethane resin, polythiourethane resin, etc.)] or thermo-curable resins [for example, (meth)acrylic resins, epoxy resins, diallyl resins, polyester resins (polyester resin, polyester carbonate resin, polycarbonate resin, polythioester resin, etc.), polyether resins, polysulfide resins (polyadditives by enthiol reaction (enthiol resin), etc.), polyurethane resins (polyurethane resin, polythiourethane resin, etc.)].

[0265] In the applications of the aforementioned adhesives or adhesives (e.g., optical adhesives or adhesives), aromatic thiol compounds or their derivatives (compositions or cured products thereof) may function as adhesives or adhesives; compositions to which aromatic thiol compounds or their derivatives (or cured products thereof) are added as additives to other conventional adhesives or adhesives may function as adhesives or adhesives.

Claims

1. A method for purifying aromatic thiol compounds in which at least one mercapto group is substituted on an aromatic ring, A base mixing step involves mixing the aromatic thiol compound, a base component, and an aqueous solvent. From the mixture obtained in this base mixing step, a separation step is performed to remove insoluble matter. This separation step includes an acid mixing step in which an acid component is mixed with the solution obtained in this separation step; A purification method for the aromatic thiol compound, wherein the aromatic thiol compound is a naphthalenedithiol compound having two mercapto groups at any of the substitutional positions selected from the group consisting of the 1,6-, 2,6-, and 2,7- positions of the naphthalene ring.

2. The purification method according to claim 1, wherein the aqueous solvent comprises at least one selected from water and alcohol.

3. The purification method according to claim 1 or 2, wherein the proportion of the aqueous solvent is 100 to 3000 parts by mass per 100 parts by mass of the aromatic thiol compound.

4. The purification method according to claim 1 or 2, wherein the base mixing step is performed in the presence of a reducing agent and / or a polymerization inhibitor.

5. The purification method according to claim 4, wherein the reducing agent and / or polymerization inhibitor comprises at least an alkali metal boron hydride.

6. The purification method according to claim 4, wherein the total amount ratio of the reducing agent and polymerization inhibitor is 0.001 to 0.1 moles per mole of mercapto group of the aromatic thiol compound.

7. The purification method according to claim 1 or 2, wherein the basic component comprises at least an alkali metal hydroxide.

8. The purification method according to claim 1 or 2, wherein the proportion of the base component is 1 to 2 moles per mole of mercapto group of the aromatic thiol compound.

9. The purification method according to claim 1 or 2, wherein the mixture obtained in the base mixing step is heated to a temperature of 50°C or higher.

10. The purification method according to claim 1 or 2, wherein the base mixing step is performed under an inert gas atmosphere.

11. The purification method according to claim 1 or 2, wherein the yield is 85 mol% or more.

12. The purification method according to claim 1 or 2, wherein the content of the aromatic thiol compound is 85% by mass or more in the crude product before purification and 95% by mass or more in the purified product after purification.

13. The purification method according to claim 1 or 2, which reduces the content of the polymer of the aromatic thiol compound.

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