Process for producing bisnaphthoic acid derivatives

Abstract

To provide a method capable of industrially advantageously producing a bisnaphthoic acid derivative having a high refractive index and high heat resistance.SOLUTION: The method for producing a bisnaphthoic acid derivative represented by formula (1) includes a step of etherifying a compound represented by formula (2) with an etherifying agent. (In the formulae, R1a and R1b each independently represent a hydrocarbon group; R2a and R2b each independently represent a substituent; k1 and k2 each independently represent an integer of 0-5; and R3a and R3b each independently represent an alkoxy group.)SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing bisnaphthoic acid derivatives such as 2,2'-dialkoxy-6,6'-dialkoxycarbonyl-1,1'-binaphthyl, which are useful as polymerization components such as polyester resins, improve refractive index and heat resistance, and are useful for reducing birefringence.

Background Art

[0002] Bisnaphthoic acid derivatives are expected to improve the optical and thermal properties of polyester resins because of their high refractive index and heat resistance.

[0003] Regarding a method for producing such bisnaphthoic acid derivatives, Japanese Patent Application Laid-Open No. 2002-316961 (Patent Document 1) describes that 2-hydroxy-3-methoxycarbonylnaphthalene was subjected to oxidative coupling in a nitrogen-containing polar solvent in the presence of a copper salt to obtain 2,2'-dihydroxy-3,3'-dimethoxycarbonyl-1,1'-binaphthyl. Japanese Patent Application Laid-Open No. 2020-075980 (Patent Document 2) discloses bis(3-methoxy-2-naphthoic acid methyl) as a first dicarboxylic acid component of a polyester resin. In the synthesis example of this document, a methyl esterification step of methyl esterifying 3-hydroxy-2-naphthoic acid to prepare methyl 3-hydroxy-2-naphthoate; a coupling step of subjecting the compound produced in this step to oxidative coupling to prepare 2,2'-dihydroxy-3,3'-bis(methoxycarbonyl)-1,1'-binaphthyl; and a methoxylation step of reacting the binaphthyl compound produced in this step with methyl iodide, through which 2,2'-dimethoxy-3,3'-bis(methoxycarbonyl)-1,1'-binaphthyl (2,3-BMN-m) was obtained. Patent Document 2 further describes that BMN-m as a dicarboxylic acid component was reacted with ethylene glycol and 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene as a diol component to obtain a polyester resin having a high refractive index and glass transition temperature and a small birefringence.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the polyester resin using the bisnaphthoic acid derivative described in these documents as the dicarboxylic acid component still does not have sufficient refractive index and heat resistance. Therefore, there is a need for a bisnaphthoic acid derivative for improving the refractive index and heat resistance of the polyester resin.

[0006] In addition, in the method described in Patent Document 2 using hydroxynaphthoic acid as a starting material, complicated separation and purification operations are required in each reaction step. For example, in the methylation step, concentration after the reaction, washing of the organic layer separated using methyl isobutyl ketone (MIBK) and ion-exchanged water, concentration of the organic layer, and crystallization operation from methanol are required. In the methoxylation step, concentration after the reaction, washing of the organic layer separated using MIBK and ion-exchanged water, concentration of the organic layer, and crystallization operation from 2-propanol are required. Also, a large amount of MIBK is used to separate the organic layer. Therefore, the method of Patent Document 2 requires many separation and purification steps and cannot industrially advantageously produce the bisnaphthoic acid derivative.

[0007] Furthermore, when a compound in which at least one of the hydroxyl groups at the 2,2'-positions of the 1,1'-binaphthyl ring is not etherified (hydroxyl form such as a half-ether form) is produced in the methoxylation step, there is a concern that it may be colored due to the naphthol structure, and in some applications, the phenolic hydroxyl group may have an adverse effect. For example, when used as a polymerization component, it may inhibit the polymerization reaction. Such free hydroxyl forms can be removed using column chromatography or the like, and a high-purity bisnaphthoic acid derivative can be produced. However, column chromatography is complicated in operation, and using column chromatography greatly reduces the production efficiency of the bisnaphthoic acid derivative.

[0008] Therefore, an object of the present invention is to provide a method capable of industrially advantageously producing a bisnaphthoic acid derivative having a high refractive index and high heat resistance.

Means for Solving the Problems

[0009] As a result of intensive studies to achieve the above object, the present inventors have found that a bisnaphthoic acid derivative having a hydrocarbonoxy group such as methoxy at the 2,2'-position of 1,1'-binaphthyl and an alkoxycarbonyl group such as methoxycarbonyl at the 6,6'-position has a higher refractive index and a higher heat resistance than a bisnaphthoic acid derivative having an alkoxycarbonyl group introduced at the 3,3'-position such as 2,3-BMN-m. A resin having a high refractive index and high heat resistance can be obtained. A purification treatment that requires complicated operations such as column chromatography is unnecessary, and the free hydroxyl form can be removed by a simple operation such as crystallization. Therefore, its production is industrially advantageous. Based on these findings, the present invention has been completed.

[0010] That is, in the method for producing a bisnaphthoic acid derivative of the present invention, a bisnaphthoic acid derivative represented by the following formula (1) is produced through an etherification step of etherifying a compound represented by the following formula (2) with an etherifying agent.

[0011]

Chemical formula

[0012] (In the formula, R 1a and R 1b each independently represent a hydrocarbon group, R 2a and R 2b each independently represent a substituent, k1 and k2 each independently represent an integer from 0 to 5, and R 3a and R 3b each independently represent an alkoxy group)

[0013] In the above formula (1) and formula (2), R 1a and R 1b may be an alkyl group (particularly, a C 1-4 alkyl group), and R 2a and R 2b are a halogen atom or an alkyl group (particularly, a C 1-4It may also be an (alkyl group), k1 and k2 may be integers from 0 to 2 (particularly 0 or 1), and R 3a and R 3b may be an alkoxy group (particularly a C 1-4 alkoxy group).

[0014] In this method, impurities may be removed from the reaction mixture, and the compound represented by the formula (1) may be recovered as crystals. For example, the crystallized product from the reaction mixture may be dissolved in an organic solvent, impurities may be removed from the organic solvent solution, the compound represented by the formula (1) may be crystallized from the organic solvent solution, and recovered as crystals; the compound represented by the formula (2) may be etherified with an etherifying agent corresponding to R 1a and R 1b such as haloalkyls in the presence of a base, and after the organic solvent solution of the crystallized product from the reaction mixture is adsorbed with an adsorbent, the compound represented by the formula (1) may be crystallized from the organic solvent solution. As the etherifying agent, a compound for forming an ether with the substituents R 1a and R 1b which are hydrocarbon groups at the 2,2'-positions in the compound represented by the formula (2) (hereinafter referred to as "the etherifying agent corresponding to R 1a and R 1b ") can be mentioned. Specifically, it is exemplified in the "etherification step" column described later. Further, by the crystallization operation after etherification, free hydroxyl forms, for example, monoether forms such as 2-methoxy-6,6'-bis(methoxycarbonyl)-1,1'-binaphthyl can be effectively removed, and the bisnaphthoic acid derivative represented by the formula (1) can be obtained as high-purity crystals.

[0015] The compound represented by the formula (2) can be prepared by a coupling step of coupling the compounds (naphthoic acid esters) represented by the following formulas (3a) and (3b), and the compounds represented by the formulas (3a) and (3b) can be prepared by an esterification step of esterifying the compounds (naphthoic acid or its derivatives) represented by the following formulas (4a) and (4b).

[0016] [Chemical formula]

[0017] (In the formula, R 2a and R 2b each independently represents a substituent, k1 and k2 each independently represent an integer from 0 to 5, and R 3a and R 3b each independently represent an alkoxy group)

[0018] In the esterification step (esterification reaction), the compounds represented by the above formulas (4a) and (4b) (naphthoic acid derivatives having a hydroxy group at the 2-position and a carboxy group at the 6-position) and the following formulas (5a) and (5b): R 3a H (5a) R 3b H (5b) (R 3a and R 3b are the same as above) The alcohol represented by (hereinafter referred to as "the alcohol corresponding to R 3a and R 3b ) can be reacted in the presence of an acid catalyst to obtain a reaction mixture. Further, in the separation and purification step, the compounds represented by the above formulas (3a) and (3b) may be crystallized from the obtained reaction mixture. For example, in the above esterification step, the compounds represented by the above formulas (4a) and (4b) and the C 3a and R 3b corresponding to R 1-4 alcohol are esterified by reacting in the presence of a soluble acid catalyst such as an inorganic acid, and in the above separation and purification step, a poor solvent is added to the reaction mixture for crystallization, and the compounds represented by the above formulas (3a) and (3b) may be crystallized.

[0019] In the coupling step (coupling reaction), the compounds represented by the formulas (3a) and (3b) (crystallized compounds) may be subjected to oxidative coupling in an organic solvent in the presence of a copper salt. Further, if necessary, after the coupling reaction, the acid catalyst remaining in the reaction mixture may be neutralized or deactivated, or removed. The neutralization or deactivation of the acid catalyst may be carried out by adding a base to the reaction mixture to neutralize or deactivate and remove the soluble acid catalyst in the esterification reaction. The coupling reaction may be carried out in a nitrogen-containing aprotic polar solvent.

[0020] In the etherification step (etherification reaction), the compound represented by the formula (2) is etherified with a C 1a alkyl etherifying agent corresponding to R 1b and R 1-4 in the presence of a base. The crystallized product from the reaction mixture may be dissolved in an organic solvent, and after the organic solvent solution is adsorbed with an adsorbent, the compound represented by the formula (1) may be crystallized from the organic solvent solution.

[0021] The present invention also includes a compound represented by the formula (1) and in the form of crystals. Such compounds are novel compounds. For example, in the formula (1), R 1a and R 1b are independently linear or branched C 1-5 alkyl groups, and R 3a and R 3b are independently linear or branched C 1-6 alkoxy groups.

[0022] In the present specification and claims, the number of carbon atoms of a substituent may be indicated by C1, C6, C 10 and so on. For example, an alkyl group having 1 carbon atom is indicated as a "C1 alkyl group", and an aryl group having 6 to 10 carbon atoms is indicated as a "C 6-10 aryl group".

[0023] The compound represented by formula (1), the compound represented by formula (2), the compounds represented by formula (3a) and formula (3b), and the compounds represented by formula (4a) and formula (4b) may sometimes be simply described as "compound (1)", "compound (2)", "compounds (3a),(3b)", and "compounds (4a),(4b)", respectively.

Advantages of the Invention

[0024] In the present invention, by etherifying the compound represented by formula (2), a bisnaphthoic acid derivative (1,1'-binaphthyl derivative) having a hydrocarbonoxy group such as an alkoxy group at the 2,2'-position, an alkoxycarbonyl group at the 6,6'-position, and having high refractive index and heat resistance can be produced. Furthermore, by utilizing the crystallization operation, the bisnaphthoic acid derivative can be industrially advantageously produced with fewer separation and purification steps. Moreover, the free hydroxyl form can be removed or reduced by a simple operation such as crystallization, and the bisnaphthoic acid derivative which is a diether form can be obtained with high purity.

Embodiments for Carrying Out the Invention

[0025] In the present invention, the compound represented by formula (1) is produced.

[0026]

Chemical formula

[0027] (In the formula, R 1a and R 1b each independently represent a hydrocarbon group, R 2a and R 2b each independently represent a substituent, k1 and k2 each independently represent an integer from 0 to 5, and R 3a and R 3b each independently represent an alkoxy group)

[0028] R 1a and R 1bExamples of the hydrocarbon group represented by include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, etc. Examples of the alkyl group include linear or branched C such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, etc. 1-6 Examples include an alkyl group, etc. Examples of the cycloalkyl group include C such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, etc. 3-10 Examples include a cycloalkyl group, etc. Examples of the aryl group include C such as phenyl group, naphthyl group, biphenylyl group, etc. 6-12 Aryl group; mono- to tri-C such as methylphenyl group (or tolyl group), dimethylphenyl group (or xylyl group), etc. 1-4 Alkyl-C 6-12 Examples include an aryl group, etc. Examples of the aralkyl group include C such as benzyl group, phenethyl group, etc. 6-12 Aryl-C 1-6 Examples include an alkyl group, etc.

[0029] Among these hydrocarbon groups, an alkyl group is preferred; among the alkyl groups, a linear or branched C 1-4 alkyl group is preferred, and a linear or branched C 1-3 alkyl group is more preferred, and in particular, a C such as methyl group 1-2 alkyl group is preferred.

[0030] Note that 1a and 1b may be different from each other, but it is preferred that they are the same.

[0031] The substituents R 2a and 2b can be selected from inert substituents according to the use of the compound (1). When used as a raw material for a polymer or resin, etc., the substituents R 2a and 2bExamples include substituents that are inert to reactions such as polymerization reactions (non-reactive groups or non-polymerizable groups), for example, halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom; hydrocarbon groups such as alkyl group, cycloalkyl group, aryl group, aralkyl group (or group R h ); groups -OR corresponding to the hydrocarbon groups such as alkoxy group, cycloalkyloxy group, aryloxy group, aralkyloxy group h (wherein, R h represents the hydrocarbon group); groups -SR corresponding to the hydrocarbon groups such as alkylthio group, cycloalkylthio group, arylthio group, aralkylthio group h (wherein, R h represents the hydrocarbon group); acyl group; nitro group; cyano group; substituted amino group and the like.

[0032] Examples of the alkyl group include linear or branched C 1-10 alkyl groups, preferably linear or branched C 1-6 alkyl groups, more preferably linear or branched C 1-4 alkyl groups and the like.

[0033] Examples of the cycloalkyl group include C 5-10 cycloalkyl groups such as cyclopentyl group, cyclohexyl group and the like. Examples of the aryl group include C 6-12 aryl groups such as phenyl group, naphthyl group, biphenylyl group; alkylaryl groups and the like. Examples of the alkylaryl group include C 1-4 alkyl C 6-12 aryl groups such as methylphenyl group (tolyl group), dimethylphenyl group (xylyl group) and the like. Examples of the aralkyl group include C 6-10 aryl-C 1-4 alkyl groups such as benzyl group, phenethyl group and the like.

[0034] Group -OR hAs for the hydrocarbon group R including the preferred embodiments, h corresponding groups, for example, linear or branched C 1-10 alkoxy groups such as methoxy group and ethoxy group, C 5-10 cycloalkyloxy groups such as cyclohexyloxy group, C 6-10 aryloxy groups such as phenoxy group, C 6-10 aryl-C 1-4 alkyloxy groups and the like can be mentioned.

[0035] As for the group -SR h As for the hydrocarbon group R including the preferred embodiments, h corresponding groups, for example, linear or branched C 1-10 alkylthio groups such as methylthio group, C 5-10 cycloalkylthio groups such as cyclohexylthio group, C 6-10 arylthio groups such as phenylthio group, C 6-10 aryl-C 1-4 alkylthio groups and the like can be mentioned.

[0036] Examples of the acyl group include C 1-6 acyl groups such as acetyl group and propionyl group.

[0037] Examples of the substituted amino group include mono- or dialkylamino groups, mono- or di(alkylcarbonyl)amino groups and the like. Examples of the mono- or dialkylamino group include mono- or diC 1-4 alkylamino groups such as dimethylamino group, and examples of the mono- or bis(alkylcarbonyl)amino group include mono- or bis(C 1-4 alkyl-carbonyl)amino groups such as diacetylamino group.

[0038] Among these substituents R 2a and R 2b halogen atoms such as bromine atom and alkyl groups such as methyl group are preferred; as the alkyl group, C 1-4 alkyl group is preferred.

[0039] R 2a and R 2b The substitution numbers k1 and k2 of R 2a and R 2b may be, for example, integers of about 0 to 4, and preferably, step by step, are integers of 0 to 3, integers of 0 to 2, more preferably 0 or 1, and particularly preferably 0. k1 and k2 may be different from each other, but are preferably the same. R 2a and R 2b may be the same as or different from each other. Also, when k1 and / or k2 is an integer of 2 or more, the types of a plurality of R 2a and the types of a plurality of R 2b may be the same as or different from each other.

[0040] R 2a and R 2b The substitution positions may be any position selected from the 3rd to 5th positions, 7th to 8th positions, 3'to 5'th positions, and 7'to 8'th positions of the 1,1'-binaphthyl ring.

[0041] R 3a and R 3b Examples of the alkoxy group represented by R 1-6 and R 1-4 include linear or branched C 1-3 alkoxy groups such as methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, s-butoxy group, and t-butoxy group. Preferred alkoxy groups are linear or branched C 1-4 alkoxy groups, more preferably linear or branched C 1-3 alkoxy groups, particularly C 1-2 alkoxy groups such as methoxy group. Note that R 3a and R 3b may be different from each other, but are preferably the same.

[0042] In formula (1), R 1a and R 1bRepresentative compounds (2,2'-dialkoxy-6,6'-bis(alkoxycarbonyl)-1,1'-binaphthyl) in which R is an alkyl group include, for example, 2,2'-dimethoxy-6,6'-bis(methoxycarbonyl)-1,1'-binaphthyl, 2,2'-diethoxy-6,6'-bis(ethoxycarbonyl)-1,1'-binaphthyl, 2,2'-dimethoxy-6,6'-bis(ethoxycarbonyl)-1,1'-binaphthyl, 2,2'-diethoxy-6,6'-bis(propoxycarbonyl)-1,1'-binaphthyl, etc., of 2,2'-diC 1-6 alkoxy-6,6'-bis(C 1-6 alkoxy-carbonyl)-1,1'-binaphthyl and the like. Preferred compounds are 2,2'-diC 1-4 alkoxy-6,6'-bis(C 1-4 alkoxy-carbonyl)-1,1'-binaphthyl, particularly 2,2'-diC 1-2 alkoxy-6,6'-bis(C 1-2 alkoxy-carbonyl)-1,1'-binaphthyl.

[0043] In addition, the compounds represented by formula (1) include compounds corresponding to these compounds (the compounds in which R 1a and R 1b are alkyl groups), and compounds in which R 1a and R 1b are cycloalkyl groups, aryl groups or aralkyl groups. Such compounds include, for example, 2,2'-dicyclohexyloxy-6,6'-bis(methoxycarbonyl)-1,1'-binaphthyl and the like of 2,2'-diC 3-10 cycloalkyloxy-6,6'-bis(C 1-6 alkoxycarbonyl)-1,1'-binaphthyl; 2,2'-diphenyloxy-6,6'-bis(methoxycarbonyl)-1,1'-binaphthyl and the like of 2,2'-diC 6-10 aryloxy-6,6'-bis(C 1-6 alkoxycarbonyl)-1,1'-binaphthyl; 2,2'-dibenzyloxy-6,6'-bis(ethoxycarbonyl)-1,1'-binaphthyl and the like of 2,2'-di(C 6-10 aryl-C 1-4(Alkyloxy)-6,6'-di(C 1-6 Examples thereof include alkoxycarbonyl)-1,1'-binaphthyl and the like.

[0044] Note that the compound represented by the formula (1) also includes novel compounds. Examples of such novel compounds include those in which R 1a and R 1b are independently a linear or branched C 1-5 alkyl group, preferably a linear or branched C 1-4 alkyl group, more preferably a C 1-2 alkyl group, and R 3a and R 3b are independently a linear or branched C 1-6 alkoxy group, preferably a linear or branched C 1-4 alkoxy group, more preferably a C 1-2 alkoxy group. Examples of such novel compounds include those in which R 2a and R 2b , as well as k1 and k2, are the same as described above, including preferred substituents and the number of substitutions. Representative novel compounds include, for example, 2,2'-diC 1-4 alkoxy-6,6'-di(C 1-4 alkoxy-carbonyl)-1,1'-binaphthyl such as the above-mentioned 2,2'-dimethoxy-6,6'-dimethoxycarbonyl-1,1'-binaphthyl, particularly 2,2'-diC 1-2 alkoxy-6,6'-di(C 1-2 alkoxy-carbonyl)-1,1'-binaphthyl.

[0045] The compound represented by the formula (1) may be prepared, for example, according to the following reaction process formula. That is, the compounds represented by the following formula (4a) and formula (4b) (6-hydroxy-2-naphthoic acids (or 2-hydroxy-6-naphthoic acids)) are esterified [esterification step], and the resulting compounds represented by the following formula (3a) and formula (3b) are coupled (oxidative coupling) [coupling step], and the resulting compound represented by the following formula (2) is etherified [etherification step], whereby the compound represented by the following formula (1) can be prepared. In the present invention, at least the compound represented by the following formula (2) may be etherified to prepare the compound represented by the following formula (1).

[0046]

Chemical formula

[0047] (In the formula, R 1a and R 1b , R 2a and R 2b are the same as k1 and k2, R 3a and R 3b are the same as above)

[0048] [Esterification step] In the esterification step, the compounds represented by the formula (4a) and (4b) and the alcohols corresponding to R 3a and R 3b of the formula (3a) and (3b) are reacted in the presence of an acid catalyst for esterification to produce the compounds represented by the formula (3a) and (3b).

[0049] Examples of the compounds represented by the formula (4a) and (4b) include 6-hydroxy-2-naphthoic acids which may have substituents represented by R 2a , R 2b in the formula (1), and 6-hydroxy-2-naphthoic acid is preferred.

[0050] R 3a , R 3bExamples of the alcohol corresponding thereto include linear or branched C 1-6 alcohols such as methanol, ethanol, propanol, and isopropanol, preferably linear or branched C 1-4 alcohols, more preferably C 1-2 alcohols such as methanol. Different types of alcohols may be used as the alcohol, but it is preferable to use the same type of alcohol.

[0051] The usage ratio of the alcohol is 0.8 to 50 moles, preferably 1 to 30 moles, more preferably 1.5 to 25 moles, based on 1 mole of the total amount of the compounds represented by the formulas (4a) and (4b); usually, an excess mole, for example, 2 to 30 moles, preferably 5 to 25 moles, particularly 10 to 20 moles. The usage ratio of the alcohol is preferably an excess mole with respect to the compounds represented by the formulas (4a) and (4b), and is 50 to 500 parts by mass, preferably 100 to 400 parts by mass, more preferably 200 to 300 parts by mass, based on 100 parts by mass of the total amount of the compounds represented by the formulas (4a) and (4b).

[0052] The esterification reaction may be carried out in the presence of a conventional esterification catalyst. Examples of the esterification catalyst include acid catalysts; base catalysts; alkoxides such as metal alkoxides, specifically titanium(IV) alkoxides such as titanium(IV) tetraisopropoxide. Among these catalysts, acid catalysts can be preferably used.

[0053] The acid catalyst may be any of Bronsted acids; Lewis acids such as boron trifluoride etherate and tin tetrachloride. The Bronsted acid may be a soluble acid such as an inorganic acid or an organic acid (a non-solid acid soluble in the reaction system); a supported catalyst in which a perfluoroalkylsulfonic acid resin is supported on a carrier such as a cation exchange resin or silica, or a solid acid such as a phenolsulfonic acid resin. The solid acid may be porous. Furthermore, these acid catalysts may be hydrates. These acid catalysts may be used alone or in combination of two or more.

[0054] Examples of the inorganic acid include strong acids, specifically, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, etc.; homo- or heteropolyacids, specifically, tungstophosphoric acid, molybdophosphoric acid, tungstosilicic acid, molybdosilicic acid, phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, and / or silicomolybdic acid, etc.

[0055] Examples of the organic acid include sulfonic acids, specifically, alkanesulfonic acids such as methanesulfonic acid and ethanesulfonic acid, fluoroalkanesulfonic acids such as trifluoromethanesulfonic acid, and arenesulfonic acids such as p-toluenesulfonic acid, etc.

[0056] In the present invention, even when a soluble acid catalyst (non-solid acid) such as a soluble inorganic acid is used, it can be removed in a small number of separation and purification steps. Therefore, as the acid catalyst, soluble inorganic acids and soluble organic acids (non-solid acids), for example, sulfuric acid such as concentrated sulfuric acid, can be used.

[0057] In addition, if necessary, the acid catalyst may be used in combination with boric acid; boric acid esters such as trimethyl borate, triethyl borate, tributyl borate, and triamyl borate.

[0058] The amount of the esterification catalyst used can be selected from the range of 0.001 to 1 mol, for example, 0.01 to 0.8 mol, preferably 0.05 to 0.7 mol, more preferably 0.1 to 0.7 mol, per 1 mol of the total amount of the compounds represented by formulas (4a) and (4b). The amount of the esterification catalyst used is 1 to 50 parts by mass, preferably 5 to 40 parts by mass, more preferably 10 to 30 parts by mass, particularly 20 to 30 parts by mass, per 100 parts by mass of the total amount of the compounds represented by formulas (4a) and (4b).

[0059] The esterification reaction can be carried out in an organic solvent inert to the reaction. Examples of the organic solvent include hydrocarbons such as hexane, cyclohexane, toluene, and xylene; ketones such as acetone and methyl ethyl ketone; ethers such as dioxane, tetrahydrofuran, and diisopropyl ether; nitriles such as acetonitrile; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; and sulfoxides such as dimethyl sulfoxide. These solvents may be used as a mixed solvent. Also, the alcohol may be used as the reaction solvent.

[0060] The reaction temperature is, for example, 50 to 120 °C, preferably 60 to 100 °C. The reaction may be carried out at the reflux temperature. The reaction time may be, for example, about 1 to 24 hours.

[0061] The reaction can be carried out with stirring in air or in an inert atmosphere such as nitrogen gas or noble gas, and may be carried out under normal pressure, under pressure or under reduced pressure. The reaction can be carried out while dehydrating from the reaction system, and if necessary, may be carried out in the presence of a dehydrating agent.

[0062] [Separation and purification step] After completion of the reaction, the compounds (6-hydroxy-2-naphthoic acid esters) represented by the formulas (3a) and (3b) thus produced may be separated and purified by conventional methods, for example, separation and purification means such as neutralization, washing, dehydration, filtration, adsorption, concentration, extraction, crystallization, reprecipitation, centrifugation, column chromatography, or means combining these. For example, the compounds (3a) and (3b) may be extracted from the reaction mixture with an organic solvent, the organic layer may be washed by water washing or the like to remove the acid catalyst, the organic layer may be concentrated, and crystallization may be carried out from the organic solvent solution of the concentrate for separation and purification. In the above extraction, an organic solvent and water may be added to the reaction mixture, and liquid separation may be carried out to extract the compounds (3a) and (3b) into the organic layer. To the concentrate of the organic layer, a poor solvent such as methanol may be added, heated and dissolved, and cooled for crystallization to separate the compounds (3a) and (3b) as crystals.

[0063] Alternatively, an organic solvent may be added to the reaction mixture or its concentrate and dissolved, and the organic layer may be washed with water to remove the acid catalyst. To the concentrate of the organic layer, a poor solvent such as methanol may be added and heated for dissolution, followed by cooling and crystallization to separate compounds (3a) and (3b) as crystals.

[0064] In a preferred method, in order to reduce the separation and purification steps, compounds (3a) and (3b) may be crystallized from the reaction mixture. For example, a poor solvent may be added to the reaction mixture for crystallization; when crystals are formed by cooling, crystallization may be carried out without adding a poor solvent to the reaction mixture. Examples of the poor solvent include alcohols such as water, methanol, ethanol, and isopropanol, and these solvents may be used alone or as a mixed solvent. A preferred poor solvent is an alcohol corresponding to the reaction component, such as methanol, in order to suppress hydrolysis. In the mode of using a poor solvent, (a) when crystals are formed after adding a poor solvent to the reaction mixture, it may be heated to redissolve the crystals, crystallized from the resulting mixture, and the formed crystals may be collected by filtration; (b) after adding a poor solvent to the reaction mixture, without redissolving the formed crystals, the slurry (or suspension) containing the crystals (precipitated crystals) may be cooled (left to cool or gradually cooled), and the formed crystals may be collected by filtration. In the latter method (b), if necessary, while stirring, the crystals may be washed with a poor solvent while dispersing the crystals under heating or warming. In method (b), the temperature for dispersion washing with a poor solvent is, for example, 35 to 80°C, preferably 40 to 70°C, more preferably 45 to 65°C, and even more preferably 50 to 60°C. Method (b) is preferred in terms of improving the purity of the target product. The acid catalyst and / or solvent of the reaction system may remain in the formed crystals, and such crystals may be used as crude crystals and subjected to the subsequent coupling reaction.

[0065] Even when a soluble acid catalyst (non-solid acid catalyst) is used in the esterification reaction, the soluble acid catalyst can be removed by filtering off the crystallized product. If necessary, a base may be added to the reaction mixture to deactivate or neutralize the remaining acid catalyst, and if necessary, the generated salt may be removed, and then the compounds (3a) and (3b) may be crystallized from the reaction mixture.

[0066] [Coupling Step] In the coupling step, conventional coupling reactions, such as coupling reactions using a palladium catalyst, a nickel catalyst, etc., can also be employed, but a preferred coupling reaction is an oxidative coupling reaction. In this oxidative coupling reaction, not only is the generation of impurities small and the separation and purification of the reaction product easy, but the reaction product may also be subjected to the subsequent etherification reaction without separation and purification.

[0067] The oxidative coupling can be carried out in an organic solvent in the presence of a catalyst using the compounds (or crystallizates) represented by the formulas (3a) and (3b), and the compound represented by the formula (2) can be produced. Examples of the catalyst include copper salts and oxidases. Examples of the copper salts include copper halides such as copper(I) chloride, copper(II) chloride, copper(I) bromide, copper(II) bromide, and copper(I) iodide; copper carboxylates such as copper(II) formate and copper(II) acetate; copper sulfonates such as copper(II) mesylate and copper(II) tosylate; and copper complexes such as copper(I)-amine complexes and copper(II)-amine complexes. Examples of the amine of the copper complex (or copper complex salt) include alkylamines and heterocyclic amines. Examples of the alkylamines include primary alkylamines such as methylamine, ethylamine, butylamine, hexylamine, and 2-ethoxyethylamine; secondary alkylamines having an alkyl group corresponding to these primary amines, tertiary alkylamines having an alkyl group corresponding to these primary amines, and tertiary amines such as N,N'-diethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, and N,N,N',N'-tetraethylethylenediamine. Examples of the heterocyclic amines include non-aromatic amines such as piperidine, piperazine, and morpholine, and aromatic amines such as pyridine. Examples of the oxidase include laccase, such as laccase derived from fungi such as Trametes or Coriolus, and laccase derived from microorganisms such as Bacillus. These oxidases can be obtained from depository institutions or the market. For example, laccase of the genus Trametes can be obtained from Sigma-Aldrich as Trametes versicolor. For these oxidases and the oxidative coupling reaction, reference can be made to International Publication No. 2016 / 050988.

[0068] These catalysts can be used alone or in combination of two or more. Among these catalysts, copper halides are preferred, copper(I) halides are more preferred, and copper(I) chloride is particularly preferred.

[0069] The proportion of the catalyst may be, for example, about 0.0001 to 1 mol, 0.001 to 0.8 mol, preferably 0.005 to 0.5 mol, and more preferably 0.01 to 0.2 mol, relative to 1 mol of the total amount of the compounds represented by the above formulas (3a) and (3b).

[0070] The organic solvent may be any solvent that is inert to the reaction. Examples thereof include hydrocarbons such as hexane and toluene, esters such as ethyl acetate, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane, tetrahydrofuran, diethyl ether, and isopropyl ether, and nitrogen-containing aprotic polar solvents. These solvents can be used alone or in combination of two or more. Preferred solvents are nitrogen-containing aprotic polar solvents. Examples of such nitrogen-containing aprotic polar solvents include amides, ureas, anilines, morpholines, pyridines, and the like.

[0071] Examples of amides include N,N-dialkyl-substituted amides such as N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylpropionamide, and N-methylacetanilide, and substituted amides such as N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidinone). Examples of ureas include tetraalkylureas such as tetramethylurea or tetraethylurea. Examples of anilines include N,N-substituted anilines such as N,N-dimethylaniline and N,N-dimethyl-methoxyaniline. Examples of morpholines include morpholine and N-methylmorpholine. Examples of pyridines include pyridine and 2-methylpyridine. 1-6 These solvents can be used alone or in combination of two or more. Among these solvents, amides are preferred, and chain amides such as N,N-dimethylformamide and N,N-dimethylacetamide, and cyclic amides such as N-methyl-2-pyrrolidone are preferred in terms of solubility and reactivity.

[0072] These solvents can be used alone or in combination of two or more. Among these solvents, amides are preferred, and chain amides such as N,N-dimethylformamide and N,N-dimethylacetamide, and cyclic amides such as N-methyl-2-pyrrolidone are preferred in terms of solubility and reactivity.

[0073] Among amides, it is preferable to include at least N,N-substituted amides such as N,N-dimethylformamide and N,N-dimethylacetamide, and more preferably to include N,N-diC 1-4 alkyl-substituted amides, and still more preferably to include N,N-diC 1-3 alkylformamide.

[0074] Among amides containing N,N-substituted amides, a mixed solvent of chain amides such as N,N-substituted amides and cyclic amides such as pyrrolidones is preferable, and N,N-diC 1-4 alkyl-substituted amides and N-C 1-4 alkylpyrrolidone mixed solvent is more preferable, and N,N-diC 1-3 alkylformamide and N-C 1-3 alkylpyrrolidone mixed solvent is even more preferable.

[0075] When the amide is a mixed solvent of N,N-substituted amides and pyrrolidones, the proportion of pyrrolidones is, for example, 1 to 100 parts by mass, preferably 3 to 50 parts by mass, more preferably 5 to 30 parts by mass, and even more preferably 7 to 20 parts by mass with respect to 100 parts by mass of N,N-substituted amides.

[0076] The amount of the solvent used is not particularly limited, and may be, for example, about 10 to 5000 parts by mass, 20 to 1000 parts by mass, preferably 30 to 500 parts by mass, more preferably 50 to 150 parts by mass, and particularly 80 to 120 parts by mass with respect to 100 parts by mass of the total amount of the compounds represented by the above formulas (3a) and (3b). When the solvent is a mixed solvent of N,N-substituted amides and pyrrolidones, the proportion of the solvent is, for example, 50 to 1000 parts by mass, preferably 100 to 500 parts by mass, more preferably 200 to 400 parts by mass, and even more preferably 250 to 300 parts by mass with respect to 100 parts by mass of the total amount of the compounds represented by the above formulas (3a) and (3b).

[0077] The reaction can be carried out with stirring in the presence of oxygen, and can be carried out under normal pressure, under pressure or under reduced pressure. In the oxidative coupling using a catalyst such as copper(I) chloride, the reaction can be carried out while introducing oxygen into the reaction system, and oxygen may be introduced into the reaction system as a mixed gas with an inert gas such as nitrogen gas or rare gas, for example, air or a mixed gas of oxygen and nitrogen. The introduction amount of air may be, for example, 0.1 to 20 L / min, preferably 0.5 to 15 L / min, more preferably 1 to 10 L / min, based on the compounds represented by formulas (3a) and (3b) in an amount of about 10 to 200 moles. The introduction amount of the mixed gas of oxygen and nitrogen may be, for example, 0.01 to 10 L / min, preferably 0.05 to 1 L / min, more preferably 0.1 to 0.5 L / min, based on the compounds represented by formulas (3a) and (3b) in an amount of about 0.1 to 10 moles. Air or an oxygen-containing gas may be introduced while bubbling into the reaction system. In such a reaction system, the catalytic activity is regenerated by oxygen, and the amount of catalyst can be reduced.

[0078] The reaction temperature is, for example, 40 to 120°C, preferably 50 to 100°C, particularly 60 to 80°C. The reaction time may be, for example, about 1 to 48 hours, 6 to 40 hours, preferably 12 to 36 hours. When using an oxidase as the catalyst, the reaction temperature is 15 to 50°C, preferably room temperature (20 to 25°C).

[0079] After completion of the reaction, the produced compound (2) may be separated and purified by the same conventional methods as described above, for example, separation and purification means such as neutralization, washing, dehydration, filtration, adsorption, concentration, extraction, crystallization, reprecipitation, centrifugation, column chromatography, etc., or means combining these. For example, a poor solvent such as water, methanol, ethanol, etc., particularly water, may be added to the reaction mixture to crystallize compound (2), and the crystallized product may be recovered as crystals. In another method, impurities that inhibit the subsequent etherification reaction are removed from the reaction mixture and subjected to the etherification reaction. For example, the acid catalyst used in the esterification step may be removed and subjected to the etherification reaction, or for example, a base may be added to the reaction mixture to deactivate or neutralize the remaining acid catalyst and then subjected to the etherification reaction.

[0080] From the viewpoint of highly improving the purity of the target product, it is preferable to combine a crystallization method and a method of adding a base for neutralization for compound (2). From the viewpoint of the balance between the purity of the target product and the production efficiency, the method of adding a base for neutralization alone is preferable.

[0081] When neutralizing with a base, in particular, since most of the acid catalyst (especially a soluble acid catalyst) can be removed by crystallization and filtration from the esterification reaction mixture, without neutralizing or deactivating the acid catalyst from the esterification reaction mixture, the crude crystals (crude crystals with residual acid catalyst) crystallized from the reaction mixture of the esterification reaction are subjected to a coupling reaction in an organic solvent, a base is added to the resulting reaction mixture to neutralize or deactivate the acid catalyst, and it may be subjected to a subsequent etherification step.

[0082] Examples of the base include inorganic bases such as alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkali metal carbonates such as sodium carbonate, potassium carbonate, and cesium carbonate; and alkali metal hydrogen carbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate. Preferred bases are alkali metal carbonates and alkali metal hydrogen carbonates.

[0083] The amount of the base used only needs to be able to neutralize or deactivate the remaining acid catalyst, and is 0.01 to 75 parts by mass, preferably 1 to 50 parts by mass, more preferably 5 to 35 parts by mass, particularly 10 to 30 parts by mass, based on 100 parts by mass of the produced compound (2).

[0084] If necessary, the organic solvent may be distilled off to adjust the concentration of compound (2) in the etherification reaction. Further, after distilling off the organic solvent, it may be solvent-exchanged with the organic solvent used in the etherification reaction of the next step. Since the purity of the target product can be improved by solvent-exchange, when solvent-exchanging, from the viewpoint of the balance between the purity of the target product and the production efficiency, in the coupling step, it is preferable to subject compound (2) to an etherification reaction without performing either crystallization or neutralization.

[0085] [Etherification Step] In the etherification step, compound (2) [2,2'-dihydroxy-6,6'-bis(alkoxycarbonyl)-1,1'-binaphthyls] is reacted with an etherifying agent corresponding to hydrocarbon groups R 1a , R 1b to etherify the hydroxyl groups at the 2,2'-positions of the 1,1'-binaphthyl ring and produce compound (2).

[0086] Examples of the etherifying agent corresponding to the alkyl groups R 1a , R 1b include haloalkyls (alkyl halides), dialkyl sulfates, alkyl tosylates, alkyl mesylates, etc. Examples of the halogen atom of haloalkyls include iodine, bromine, chlorine atoms, etc., with an iodine atom or a bromine atom being preferred, and an iodine atom being more preferred. Examples of haloalkyls include alkyl iodides, alkyl bromides, alkyl chlorides, etc., and preferably C 1-6 alkyl iodides such as methyl iodide. Examples of dialkyl sulfates include C 1-6 alkyl sulfates such as dimethyl sulfate. Examples of alkyl tosylates include C 1-6 alkyl-tosylates such as methyl tosylate and ethyl tosylate, and examples of alkyl mesylates include C 1-6 alkyl-mesylates such as methyl mesylate and ethyl mesylate.

[0087] Examples of the etherifying agent corresponding to the R 1a , R 1b being a cycloalkyl group, an aryl group or an aralkyl group include compounds corresponding to the exemplified etherifying agents (the etherifying agents corresponding to the case where R 1a , R 1b is an alkyl group).

[0088] These etherifying agents can be used alone or in combination of two or more. Among these etherifying agents, alkyl etherifying agents, preferably haloalkyls, alkyl sulfates, and more preferably C1-6 C alkyls such as alkyl and dimethyl sulfate 1-6 C alkyls, especially C iodide 1-4 C alkyls such as alkyl and alkyl sulfate 1-4 is an alkyl. The etherifying agent is R 1a and R 1b may be different compounds of (hydrocarbon group, especially alkyl group), but it is preferably the same compound, that is, a single compound.

[0089] The usage ratio of the etherifying agent may be, for example, about 2 to 10 moles, 2.1 to 8 moles, preferably 2.2 to 5 moles, more preferably 2.5 to 3.5 moles, and particularly 2.7 to 3.3 moles, per 1 mole of the compound represented by formula (2) (6,6'-bis(alkoxycarbonyl)-2,2'-dihydroxy-1,1'-binaphthyls).

[0090] The etherification reaction may be carried out in the presence of a base. Examples of the base include inorganic bases and organic bases such as triethylamine and pyridine, and inorganic bases are often used. Examples of the inorganic base include alkali metal hydroxides, alkali metal carbonates, alkali metal hydrogen carbonates, and alkali metal hydrides. Examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide. Examples of the alkali metal carbonate include sodium carbonate, potassium carbonate, and cesium carbonate. Examples of the alkali metal hydrogen carbonate include sodium hydrogen carbonate and potassium hydrogen carbonate. Examples of the alkali metal hydride include sodium hydride and potassium hydride.

[0091] These bases can be used alone or in combination of two or more. Among these bases, alkali metal carbonates such as potassium carbonate and alkali metal hydrogen carbonates are preferred.

[0092] The ratio of the base may be, for example, about 0.01 to 10 moles, 0.02 to 5 moles, preferably 0.05 to 2.5 moles, more preferably 0.07 to 1 mole, and particularly 0.1 to 0.5 mole, per 1 mole of compound (2).

[0093] The reaction may be carried out in the presence of a solvent. Examples of the solvent include ketones such as acetone and methyl ethyl ketone; ethers such as dioxane, tetrahydrofuran, dimethyl ether, and diisopropyl ether; nitriles such as acetonitrile and propionitrile; amides such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidinone; sulfoxides such as dimethyl sulfoxide; hydrocarbons, specifically, aliphatic or alicyclic hydrocarbons such as hexane, and aromatic hydrocarbons such as benzene and toluene.

[0094] These solvents can be used alone or in combination of two or more. Among these solvents, aprotic polar solvents, particularly solvents containing nitrogen-containing aprotic polar solvents such as amides, for example, amides such as N,N-dimethylformamide and N-methyl-2-pyrrolidinone, are preferred. The reason why amides are preferred is that amides are often used as solvents in the coupling reaction, and the solvent used in the coupling reaction (coupling step) can be used as it is, and the solubility is also excellent. The proportion of amides may be 1% by mass or more in the solvent, for example, 5% by mass or more, preferably 10% by mass or more. The proportion of amides may be 50% by mass or more in the solvent, or may be 100% by mass.

[0095] When combining amides with other solvents (solvents other than amides), ketones and hydrocarbons are preferred as the other solvents, and ketones are particularly preferred. Examples of the ketones include acetone, methyl ethyl ketone (MEK), methyl propyl ketone, methyl isopropyl ketone, diethyl ketone, methyl isobutyl ketone (MIBK), diisopropyl ketone, butyl propyl ketone, etc. These ketones can be used alone or in combination of two or more. Among these ketones, C such as MEK 3-8Chain ketones are preferred. In particular, by substituting a part of the amides used in the coupling reaction with other solvents, the purity of the target product can be improved.

[0096] When using a mixed solvent of amides and other solvents as the solvent, the proportion of amides is, for example, 1 to 100 parts by mass, preferably 5 to 80 parts by mass, more preferably 10 to 50 parts by mass, still more preferably 15 to 40 parts by mass, and most preferably 20 to 30 parts by mass with respect to 100 parts by mass of other solvents. If the proportion of amides is too small, solvent substitution becomes difficult and the production efficiency may decrease. If it is too large, the purity of the target product may not be improved.

[0097] The usage ratio of the solvent is not particularly limited and may be, for example, about 10 to 1000 parts by mass, preferably 50 to 750 parts by mass, more preferably 100 to 300 parts by mass with respect to 100 parts by mass of the compound represented by the formula (2) (6,6'-bis(alkoxycarbonyl)-2,2'-dihydroxy-1,1'-binaphthyls).

[0098] The reaction temperature is, for example, 25 to 120 °C, preferably 30 to 80 °C. The reaction time may be, for example, about 1 to 24 hours, preferably 2 to 12 hours.

[0099] The reaction can be carried out while stirring in air or in an inert atmosphere such as nitrogen gas or noble gas, and can be carried out under normal pressure, under pressure or under reduced pressure.

[0100] [Recovery step] After the reaction is completed, the resulting compound represented by the formula (1) (6,6'-bis(alkoxycarbonyl)-2,2'-dihydroxy-1,1'-binaphthyls) may be separated and purified by conventional methods, such as separation and purification means such as neutralization, washing, dehydration, filtration, adsorption, concentration, extraction, crystallization, reprecipitation, centrifugation, column chromatography, etc., or means combining these. For example, the compound (1) may be extracted from the reaction mixture with an organic solvent, the organic layer may be washed by water washing or the like to remove the base, the organic layer may be concentrated, and crystallization may be carried out from the organic solvent solution of the concentrate for separation and purification. In the above extraction, an organic solvent and water may be added to the reaction mixture, and the compound (3a), (3b) may be extracted into the organic layer by liquid separation. A poor solvent such as methanol or isopropanol may be added to the concentrate of the organic layer, heated and dissolved, and cooled for crystallization to separate the compound (1) as crystals.

[0101] Also, impurities may be removed from the reaction mixture, and the compound represented by the formula (1) may be recovered as crystals. For example, without recovering crystals by crystallization from the reaction mixture, the impurities in the reaction mixture may be removed by washing and / or a treatment agent (such as an adsorbent) described below, and the compound represented by the formula (1) may be recovered as crystals.

[0102] Furthermore, crystallized substances (crystals) may be crystallized from the reaction mixture, and the compound represented by the formula (1) may be recovered as crystals. The crystallized substances from the reaction mixture may be generated by cooling crystallization, or may be generated by adding a poor solvent to the reaction mixture (by solvent crystallization); the generated crystallized substances may be washed. The poor solvent may be water, alcohols such as methanol, ethanol, isopropanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc. The poor solvent may be a mixed solvent of these solvents, for example, a mixed solvent of water and a ketone such as methyl isobutyl ketone. A preferred poor solvent is water, or a mixed solvent of water and a water-soluble organic solvent such as ethanol, especially water. In a preferred method, crystallized substances can be generated from the reaction mixture by adding a poor solvent (by solvent crystallization).

[0103] By such crystallization operation, hydroxyl compounds such as half-ether bodies can be effectively removed or reduced, and the high-purity compound (1) can be obtained as crystals. Therefore, coloring caused by hydroxyl compounds can also be suppressed.

[0104] In a preferred method, the crystallized product from the reaction mixture may be dissolved in an organic solvent, impurities may be removed from the resulting organic solvent solution, and the compound (1) may be recovered from the organic solvent solution as a crystallized product (particularly, crystals). That is, the generated crystallized product is separated by filtration or the like and dissolved in an organic solvent, and this organic solvent solution may be washed by water washing or the like if necessary to remove impurities in the organic solvent solution. When the solvent crystallization is not performed, acid washing may be performed using an aqueous solution containing a dicarboxylic acid such as oxalic acid before water washing.

[0105] Examples of the organic solvent include alcohols such as isopropanol, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and nitriles such as acetonitrile, methoxyacetonitrile, and propionitrile. Preferred organic solvents are toluene and methyl ethyl ketone, and particularly preferably a mixed solvent thereof. Specifically, the mass ratio of aromatic hydrocarbons such as toluene to ketones such as methyl ethyl ketone can be selected from the range of about former / latter = 10 / 90 to 85 / 15, 15 / 85 to 80 / 20, preferably 20 / 80 to 60 / 40, and more preferably 25 / 75 to 50 / 50. The organic solvent having such a composition is suitable for removing impurities. The impurities may be salts of the acid catalyst used in the esterification reaction and the base added after the coupling reaction.

[0106] For the removal of the impurities, filtration may be used, but preferably adsorbents such as activated carbon, zeolite, silica gel, activated alumina, and treatment agents such as ion exchange resins can be used. Among these treatment agents, adsorbents such as activated carbon are advantageously used. The treatment with the treatment agent may be carried out by adding the treatment agent to the organic solvent solution and performing it at 10 to 40 °C or at room temperature, but in order to reduce the number of subsequent separation and purification steps, it may also be carried out under heating or under heating, for example, at 40 to 90 °C, preferably at 50 to 85 °C, more preferably at 60 to 80 °C.

[0107] After removing the impurities, if necessary, the organic solvent solution may be washed by water washing (such as washing with warm water or hot water), and the compound (1) may be crystallized from the heated or heated organic solvent solution by cooling crystallization or the like, or the composition or concentration of the organic solvent may be adjusted to crystallize the compound (1) by cooling crystallization or the like. Preferred organic solvents are mixed solvents of aromatic hydrocarbons such as toluene and ketones such as methyl ethyl ketone, and mixed solvents of ketones such as methyl ethyl ketone and nitriles such as acetonitrile. In particular, for example, the mass ratio of aromatic hydrocarbons to ketones such as methyl ethyl ketone can be selected from the range of about former / latter = 15 / 85 to 85 / 15, prepared to 20 / 80 to 80 / 20, preferably 25 / 75 to 70 / 30, more preferably 30 / 70 to 60 / 40, particularly 35 / 65 to 55 / 45, and the compound (1) may be crystallized. Also, the mass ratio of aromatic hydrocarbons such as toluene to nitriles such as acetonitrile can be selected from the range of about former / latter = 10 / 90 to 90 / 10, prepared to 20 / 80 to 80 / 20, preferably 30 / 70 to 70 / 30, more preferably 40 / 60 to 60 / 40, and the compound (1) may be crystallized. Such an organic solvent with such a composition is suitable for the crystallization of the compound (1). Therefore, the compound (1) may be crystallized by cooling crystallization or the like from the state of the organic solvent solution dissolved by heating or warming in the organic solvent.

[0108] It should be noted that the washing of the organic solvent solution by water washing or the like may be carried out at least at one of the times before and after the treatment with the treatment agent such as the adsorbent, or may be carried out both before and after the treatment.

[0109] In a preferred embodiment of the present invention, among the esterification step, coupling step, and etherification step, at least the coupling step and the etherification step, preferably all of the above steps, may be carried out in one pot to prepare compound (1). In such an embodiment, compound (1) can be efficiently prepared without sequentially transferring the reaction product of the reactor to the subsequent reactor for each reaction step. In this method, compounds (4a) and (4b) and an alcohol are esterified in the presence of an acid catalyst, and a poor solvent is added to the reaction mixture produced by this esterification reaction to crystallize the crystals of compounds (3a) and (3b); the crystallization product (crude crystals remaining with the acid catalyst) is dissolved in a nitrogen-containing aprotic polar solvent without generating it, and is subjected to an oxidative coupling reaction. A base is added to the reaction mixture containing the produced compound (2) to deactivate or neutralize the acid catalyst; compound (2) and an alkyl iodide are subjected to an etherification reaction in the presence of a base, and a poor solvent is added to the reaction mixture produced by this etherification reaction to crystallize it. The crystallization product is dissolved in a mixed solvent of aromatic hydrocarbons and ketones, and the produced solution is adsorbed with an adsorbent (or adsorbed under heating) and then cooled and crystallized to obtain compound (1) in the form of crystals.

[0110] Compound (1) produced by such an etherification reaction is, as described above, a novel compound, and may be in a liquid form at room temperature (20 °C), but is preferably in the form of crystals. The compound (1) in the form of crystals has high handleability and is industrially advantageous.

[0111] Note that not only the compound represented by the formula (1), but also in the formula (1), R 3a and R 3b are compounds in which the hydroxyl group or halogen atom, for example, 2,2'-dialkoxy-6,6'-dicarboxy-1,1'-binaphthyl, 2,2'-dialkoxy-6,6'-dihalocarbonyl-1,1'-binaphthyl are also novel.

[0112] Such compounds can be prepared from compound (1) by a conventional method. That is, R 3a and R3b The compound in which is a hydroxyl group can be prepared by hydrolyzing compound (1) in an organic solvent containing at least water in the presence of an acid catalyst, preferably a base catalyst. Examples of the organic solvent include the same hydrocarbons, ketones, ethers, nitriles, amides, and sulfoxides as described above, and these solvents may be used as a mixed solvent.

[0113] R 3a and R 3b In the compound where R is a halogen atom, 3a and R 3b The halogenating agent can be prepared by reacting a compound in which the hydroxyl group is a hydroxyl group with a halogenating agent. Examples of the halogenating agent include chlorinating agents such as thionyl chloride, sulfuryl chloride, oxalyl chloride, phosphonyl chloride, phosphorus trichloride, and phosphorus pentachloride, and brominating agents corresponding to these chlorinating agents. Among these halogenating agents, thionyl chloride and sulfuryl chloride are commonly used. The amount of the halogenating agent used is about 0.8 to 2 moles, preferably about 1 to 1.5 moles, per mole of hydroxyl group. The reaction may be carried out in an organic solvent inert to the reaction at a relatively low temperature, for example, 0 to 70°C, preferably 10 to 50°C. Examples of the organic solvent include the same organic solvents as those exemplified in the above hydrolysis section.

[0114] In addition, R 3a and R 3b The compound in which is a hydroxyl group or a halogen atom may be separated and purified by a conventional method, for example, a separation and purification means such as neutralization, washing, dehydration, filtration, adsorption, concentration, extraction, crystallization, reprecipitation, centrifugation, column chromatography, or a combination of these means.

[0115] [Use of compound (1)] The thus-obtained compound (1) has few impurities despite having few separation and purification steps, and the purity by HPLC is 98% or more, preferably 99% or more. Moreover, compound (1) has high refractive index and heat resistance. Furthermore, since the remaining free hydroxyl form (such as monoether form) has been removed or reduced from the product (such as crystals) containing compound (1), there is little risk of coloring and it does not adversely affect the reaction. Therefore, it can be used for the synthesis of low-molecular compounds such as reagents and additives.

[0116] Furthermore, compound (1) is suitable as a polymerization component (monomer) of a resin with improved properties such as refractive index and heat resistance, and is useful as a raw material for a resin for forming an optical material. Representative resins having compound (1) as a polymerization component include thermoplastic resins having compound (1) as a dicarboxylic acid component, such as polyester resins.

[0117] The polyester resin can be prepared by esterifying at least a dicarboxylic acid component containing compound (1) and a diol component by a melt polymerization method such as a transesterification method or a direct polymerization method, a solution polymerization method, an interfacial polymerization method, etc. The reaction may be carried out in the presence or absence of a solvent depending on the polymerization method. A preferred polymerization method is the melt polymerization method.

[0118] The dicarboxylic acid component may contain an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid; a second dicarboxylic acid component such as an aromatic dicarboxylic acid. Examples of the aromatic dicarboxylic acid include dicarboxylic acids having a fluorene skeleton such as 9,9-bis(2-methoxycarbonylethyl)fluorene (FDP-m); arenedicarboxylic acids such as terephthalic acid and naphthalenedicarboxylic acid. Among these dicarboxylic acid components, aromatic dicarboxylic acids, particularly dicarboxylic acids having a fluorene skeleton, are preferred. The proportion of compound (1) may be 10 to 100 mol%, preferably 25 to 80 mol%, more preferably 30 to 70 mol% based on the total dicarboxylic acid component.

[0119] Examples of the diol component include aliphatic diols such as ethylene glycol; alicyclic diols such as cyclohexanediol and cyclohexanedimethanol; aromatic diols, etc. Examples of the aromatic diol include diols having a fluorene skeleton such as 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]fluorene (BNEF), 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (BPEF), 9,9-bis[3-methyl-4-(2-hydroxyethoxy)phenyl]fluorene (BCEF), 9,9-bis[3,5-dimethyl-4-(2-hydroxyethoxy)phenyl]fluorene (BCEF), 9,9-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]fluorene (BOPPEF); diols having a biaryl skeleton such as 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthyl, etc. Among these diol components, at least aromatic diols, particularly diols having a fluorene skeleton are preferred, and BNEF and BPEF are more preferred. Further, the diol component may preferably contain an aliphatic diol such as ethylene glycol.

[0120] The usage ratio (or charging ratio) of the dicarboxylic acid component to the diol component is usually the former / latter (molar ratio) = for example, 1 / 1.2 to 1 / 0.8, preferably 1 / 1.1 to 1 / 0.9, and the reaction components such as ethylene glycol that can be distilled out from the reaction system may be in an excess amount compared to the introduction ratio into the polyester resin.

[0121] The reaction may be carried out in the presence of conventional catalysts. Examples of the catalysts include metal alkoxides such as germanium tetraethoxide, germanium - n - butoxide, tetra - n - propyl titanate, tetraisopropyl titanate, tetra - n - butyl titanate (titanium(IV) tetrabutoxide); metal organic acid salts such as calcium acetate, antimony acetate, manganese acetate, germanium oxalate, titanium oxalate; metal inorganic acid salts such as metal borates, carbonates; metal oxides such as antimony trioxide, germanium dioxide, and their hydrates may also be used. These catalysts can be used alone or in combination of two or more. Among these catalysts, manganese acetate tetrahydrate, calcium acetate monohydrate, germanium dioxide, titanium(IV) tetrabutoxide, etc. are preferred. The amount of the catalyst used is, for example, 0.01×10 -4 ~100×10 -4 mol, preferably 0.1×10 -4 ~40×10 -4 mol.

[0122] The reaction may be carried out in the presence of stabilizers such as heat stabilizers and antioxidants such as triphenyl phosphate and dibutyl phosphate, if necessary.

[0123] The reaction is usually carried out in an atmosphere of an inert gas such as nitrogen gas; noble gases such as helium. The reaction can also be carried out under reduced pressure. Usually, the transesterification reaction is often carried out in an inert gas atmosphere such as nitrogen gas, and the polycondensation reaction is often carried out under reduced pressure. The reaction temperature can be selected according to the polymerization method. For example, the reaction temperature in the melt polymerization method is 150 - 320°C, preferably 200 - 310°C, more preferably 250 - 300°C.

[0124] The generated polyester resin reflects the properties of the compound (1), has a high refractive index, high heat resistance or glass transition temperature, and can greatly reduce the Abbe number. Furthermore, an increase in birefringence can also be suppressed. Therefore, it is usually possible to achieve both a high refractive index and low birefringence, which are in a trade-off relationship, and improve optical properties such as a low Abbe number, high refractive index, and low birefringence, as well as heat resistance.

Examples

[0125] The present invention will be described in more detail below based on examples, but the present invention is not limited by these examples. The evaluation methods in the examples and comparative examples are as follows.

[0126] (Purity) Using "LC-2010CHT" manufactured by Shimadzu Corporation as an HPLC (high-performance or high-speed liquid chromatograph) device and "ODS-80TM" (4.6 mm × 250 mm 5 μm) manufactured by Tosoh Corporation as a column, the sample was dissolved in acetonitrile and measured, and the HPLC purity [area%] was calculated under the conditions shown in the following table.

[0127]

Table 1

[0128] ( 1 H-NMR) Using a nuclear magnetic resonance apparatus ("ADVANCE III HD" manufactured by BRUKER) and tetramethylsilane as an internal standard and CDCl3 as a solvent, 1 the 1H-NMR spectrum was measured.

[0129] Regarding the resin sample, based on the obtained spectrum, the integral value of the peak derived from each monomer used in the polymerization was determined, and the ratio (polymer composition ratio) of each monomer component (structural unit) introduced into the polymer was calculated.

[0130] (Residual on heating) Using a heat drying type moisture meter (manufactured by A&D Company, Limited), the initial weight W0 of the dried sample was measured. The sample was heated in an air atmosphere up to 180°C, and when the weight loss rate reached 0.1% / min or less, the weight W1 was measured. The ratio of the weight W1 to the initial weight W0 [(W1 / W0)×100] was calculated as the heating residue (weight %).

[0131] (Bulk density) 10 g of the sample was charged into a 100 mL graduated cylinder, and after shaking it up and down 10 times, the bulk density (g / mL) was simply calculated based on the volume.

[0132] (Molecular weight) The sample was dissolved in chloroform, and the weight average molecular weight Mw in terms of polystyrene was determined using gel permeation chromatography (manufactured by Tosoh Corporation, "HLC-8320GPC").

[0133] (Glass transition temperature Tg) Using a differential scanning calorimeter (manufactured by SII NanoTechnology Inc., "EXSTAR6000 DSC6220 ASD-2"), it was measured under a nitrogen atmosphere at a heating rate of 10°C / min.

[0134] (Refractive index nD) The sample was hot pressed at 200 - 240°C to form a film with a thickness of 200 - 300 μm. This film was cut into strips with a length of 20 - 30 mm and a width of 10 mm to obtain test pieces. For the obtained test pieces, using a multi-wavelength Abbe refractometer (manufactured by Atago Co., Ltd., "DR-M4 (circulating constant temperature water bath 60-C3)"), at a measurement temperature of 20°C and using diiodomethane as the contact liquid, the refractive index nD at 589 nm (D line) was measured.

[0135] (Abbe number) Using the test pieces for which the refractive index nD at 589 nm (D line) was measured, except that the measurement wavelengths were changed to 486 nm (F line) and 656 nm (C line), the refractive indices nF and nC were measured in the same manner as the refractive index nD. From the refractive indices nF, nD, and nC at each obtained wavelength, the Abbe number was calculated by the following formula.

[0136] (Abbe number) = (nD - 1) / (nF - nC).

[0137] (Birefringence (3x elongation)) By hot pressing the sample at 200 - 240°C, a film with a thickness of 200 - 600 μm was formed. This film was cut into strips of 10 mm × 50 mm, and under the temperature condition of glass transition temperature Tg + 10°C, it was uniaxially stretched at 25 mm / min so that the elongation ratio became 3 times to obtain a test piece. The obtained test piece was used with a retardation film - optical material inspection device ("RETS - 100" manufactured by Otsuka Electronics Co., Ltd.), and under the conditions of a measurement temperature of 20°C and a measurement wavelength of 600 nm, the retardation was measured by the parallel Nicol rotation method, and the value was divided by the thickness of the measurement site to calculate the birefringence (or 3 - fold birefringence).

[0138] [Comparative Example 1] According to Synthesis Example 1 described in Japanese Patent Application Laid - Open No. 2020 - 075980 (Patent Document 2), 3,3’ - bis(methoxycarbonyl) - 2,2’ - dimethoxy - 1,1’ - binaphthyl (2,3 - BMN - m) represented by the following formula was prepared.

[0139] [Chemical formula]

[0140] [Example 1] 2,2’ - dimethoxy - 6,6’ - bis(methoxycarbonyl) - 1,1’ - binaphthyl (2,6 - BMN - m) was prepared as follows.

[0141] [Esterification step] 6-Hydroxy-2-naphthoic acid (10.0 kg, 53.1 mol) and dehydrated methanol (26.0 kg) were mixed and stirred, and 98% by mass sulfuric acid (2.6 kg) was added dropwise while keeping the temperature of the mixture at 25°C or lower. After reacting with reflux dehydration for 10.5 hours, methanol was distilled off under reduced pressure. MIBK (42.0 kg) was added to the product to dissolve the reaction mixture, and then the organic layer was washed with water until the pH reached 7. After concentrating the obtained organic layer, methanol (30.0 kg) was added, dissolved at 75°C, and then cooled for crystallization. After crystals were precipitated at 45°C, it was gradually cooled and held at 10°C or lower for 1 hour, and then the precipitated crystals were filtered. After pouring cold methanol over the filtered crystals for rinsing, they were dried under reduced pressure at 60°C to obtain 8.47 kg of methyl 6-hydroxy-2-naphthoate (yield 78.8%, HPLC purity 98.5 area%).

[0142] [Coupling step] The obtained methyl 6-hydroxy-2-naphthoate (4.0 kg, 19.8 mol), N,N-dimethylformamide (4.0 kg), and copper(I) chloride (588.0 g, 5.9 mol, added in three portions) were dissolved (mixed) at 70°C, and the reaction was carried out at 70°C for 23.5 hours while bubbling air at a rate of 2 - 10 L / min. After confirming the disappearance of the raw materials by HPLC, ion-exchanged water (4.0 kg) was added, and the precipitated crystals were filtered. The filtered crystals were rinsed with ion-exchanged water and methanol in that order. Next, the crystals were dispersed in methanol at 50°C, stirred (washed), and filtered. Then, 1N hydrochloric acid (12.0 kg) was added, stirred at room temperature, filtered, and the obtained crystals were rinsed with ion-exchanged water and methanol in that order, and then dried under reduced pressure at 60°C to obtain 2.83 kg of 6,6'-bis(methoxycarbonyl)-2,2'-dihydroxy-1,1'-binaphthyl (yield 71.1%, HPLC purity 98.1 area%).

[0143] [Etherification step] The obtained 6,6'-bis(methoxycarbonyl)-2,2'-dihydroxy-1,1'-binaphthyl (1.4 kg, 3.5 mol), potassium carbonate (1.6 kg, 11.5 mol), and dehydrated N,N-dimethylformamide (7.0 kg, added in two portions) were mixed and stirred, and methyl iodide (1.5 kg, 10.4 mol) was added dropwise. Then, the mixture was stirred at 40 °C for 6 hours. After confirming the disappearance of the raw materials by HPLC, MIBK (25.8 kg) and ion-exchanged water (7.0 kg) were added, and the precipitated crystals were filtered and rinsed with ion-exchanged water. Next, the crystals were dispersed and washed with 1N hydrochloric acid (4.9 kg) and ion-exchanged water (4.9 kg) at 50 °C, filtered, and rinsed twice with ion-exchanged water at 50 °C. Further, the crystals were dispersed and washed with ion-exchanged water (10.0 kg) at 50 °C, filtered, and rinsed multiple times with ion-exchanged water and methanol. The obtained crystals were dried under reduced pressure at 60 °C to obtain 1.44 kg of crude 6,6'-bis(methoxycarbonyl)-2,2'-dimethoxy-1,1'-binaphthyl (crude 2,6-BMN-m) (yield 96%, HPLC purity 99.0 area%).

[0144] The obtained crude 6,6'-bis(methoxycarbonyl)-2,2'-dihydroxy-1,1'-binaphthyl (700 g) was heated and dissolved in THF (8.9 kg), concentrated and adsorbed onto silica gel (2.1 kg), and developed and column-purified with a mixed solvent of solvent A and solvent B in the solvent ratio (volume ratio) shown in Table 2 according to the addition order, addition amount, and number of times described in the following table.

[0145]

Table 2

[0146] The obtained solution was concentrated, dispersed and washed with methanol (2.1 kg) at room temperature, and then dried under reduced pressure at 60 °C to obtain 650 g of 6,6'-bis(methoxycarbonyl)-2,2'-dimethoxy-1,1'-binaphthyl (2,6-BMN-m) (yield 93%, HPLC purity 99.8 area%) represented by the following formula.

[0147] [Chemical formula]

[0148] 1 H-NMR (CDCl3, 300 MHz): δ (ppm) 3.8 (s, 6H), 3.9 (s, 6H), 7.1 (d, 2H), 7.5 (d, 2H), 7.8 (dd, 2H), 8.1 (d, 2H), 8.6 (s, 2H).

[0149] [Example 2] The target compound 2,6-BMN-m was prepared as follows.

[0150] [Esterification step] While mixing and stirring 6-hydroxy-2-naphthoic acid (37.6 kg, 200.0 mol) and dehydrated methanol (97.9 kg), 98% concentrated sulfuric acid (9.8 kg) was added dropwise so that the temperature of the reaction solution (mixed solution) was 25°C or lower, and the reaction was carried out while refluxing and dehydrating for 4 hours. After allowing to cool, methanol (15.1 kg) was added at 60°C, heated at 55°C for 1 hour for dispersion washing, then gradually cooled, held at 10°C or lower for 1 hour, and the precipitated crystals were filtered. By pouring cold methanol over the filtered crystals and rinsing, 48.5 kg of crude methyl 6-hydroxy-2-naphthoate (HPLC purity 98.8 area%) containing methanol and sulfuric acid was obtained.

[0151] [Coupling step] The obtained crude methyl 6-hydroxy-2-naphthoate (48.5 kg), N,N-dimethylformamide (65.9 kg), and copper(I) chloride (2.8 kg, 28.0 mol) were dissolved (mixed) at 70°C, and the reaction was carried out at 70°C for 24 hours while bubbling air at a rate of 1 - 10 L / min. After confirming the disappearance of the raw materials by HPLC, sodium hydrogen carbonate (10.6 kg) was added and stirred at 40°C for 1 hour. Then, a vacuum treatment was carried out at 300 torr or lower for 1 hour.

[0152] [Etherification step] To the obtained reaction solution, potassium carbonate (44.0 kg, 318.4 mol) and N,N-dimethylformamide (48.9 kg) were added, and while stirring, methyl iodide (41.1 kg, 289.6 mol) was added dropwise. Then, the mixture was stirred at 40 °C for 4 hours. After confirming the disappearance of the raw materials by HPLC, water (95.8 kg) was added to precipitate crystals. After filtration, the crystals were rinsed several times with water. Next, the obtained crude crystals were dissolved in methyl ethyl ketone (hereinafter also referred to as MEK; 112.9 kg) and toluene (56.5 kg) at 75 °C, and the organic layer was washed with warm water at 75 °C several times. Then, activated carbon (260.0 g) was added to the organic layer and stirred at 75 °C for 1 hour. After removing the activated carbon by filtration, a mixed solvent of toluene (94.1 kg) and MEK (75.3 kg) (temperature 75 °C) was added and dissolved, and the organic layer was washed with warm water at 75 °C several times and then subjected to cooling crystallization. After crystals were precipitated at 53 °C, the temperature was gradually lowered and held at 10 °C or lower for 1 hour, and then the precipitated crystals were filtered. After pouring cold methanol over the filtered crystals for rinsing, drying was carried out under reduced pressure at 100 °C to obtain 23.58 kg of 6,6'-bis(methoxycarbonyl)-2,2'-dimethoxy-1,1'-binaphthyl (2,6-BMN-m) (HPLC purity 99.0 area%) represented by the formula of Example 1 above.

[0153] [Example 3] The target compound was obtained in the same manner as in Example 2, except that dimethyl sulfate was used instead of methyl iodide as the methyl etherifying agent as follows.

[0154] [Esterification step] While stirring a mixture of 6-hydroxy-2-naphthoic acid (14.0 kg, 74.4 mol) and dehydrated methanol (36.4 kg), 98% concentrated sulfuric acid (3.6 kg) was added dropwise so that the temperature of the mixture became 25 °C or lower, and the reaction was carried out while refluxing and dehydrating for 4 hours. Then, methanol (5.6 kg) was added and dissolved at the reflux temperature, and then gradually cooled. After holding at 10 °C or lower for 1 hour, the precipitated crystals were filtered. By pouring cold methanol over the filtered crystals for rinsing, 17.0 kg of crude methyl 6-hydroxy-2-naphthoate containing methanol and sulfuric acid (HPLC purity 99.3 area%) was obtained.

[0155] [Coupling Step] The obtained crude methyl 6-hydroxy-2-naphthoate (2.4 kg), N,N-dimethylformamide (3.5 kg), and copper(I) chloride (147.2 g, 1.5 mol) were dissolved (mixed) at 70 °C, and reacted at 70 °C for 15 hours while bubbling air at a rate of 8 L / min. After confirming the disappearance of the raw materials by HPLC, sodium hydrogen carbonate (562.0 g) was added and stirred at 40 °C for 1 hour. Then, a vacuum treatment was performed at 300 torr or less for 1 hour.

[0156] [Etherification Step] Subsequently, potassium carbonate (4.6 kg, 33.7 mol) was added to the obtained reaction solution, and dimethyl sulfate (4.1 kg, 32.2 mol) was added dropwise while stirring. Then, it was stirred at 40 °C for 21 hours. After confirming the disappearance of the raw materials by HPLC, water (5.1 kg) was added to crystallize the crystals. After filtration, it was rinsed with water multiple times. The obtained crude crystals were dissolved in MEK (6.0 kg) and toluene (3.0 kg) at 75 °C. Then, activated carbon (280 g) was added to the organic layer and stirred at 75 °C for 1 hour. After removing the activated carbon by filtration, a mixed solvent of toluene (5.0 kg) and MEK (4.0 kg) (temperature 75 °C) was added to dissolve it. The organic layer was washed with warm water at 75 °C multiple times and then cooled for crystallization. After precipitating the crystals at 45 °C, it was gradually cooled and held at 10 °C or below for 1 hour. Then, the precipitated crystals were filtered. After pouring cold methanol onto the filtered crystals for rinsing, it was dried under reduced pressure at 100 °C to obtain 1.04 kg of 6,6'-bis(methoxycarbonyl)-2,2'-dimethoxy-1,1'-binaphthyl (2,6-BMN-m) (HPLC purity 99.3 area%).

[0157] [Example 4] The target compound 2,6-BMN-m was prepared as follows.

[0158] [Esterification Step] 6-Hydroxy-2-naphthoic acid (301.1 g, 1.6 mol) and dehydrated methanol (782.8 g) were mixed and stirred, and 98% concentrated sulfuric acid (78.3 g) was added dropwise so that the temperature of the reaction solution (mixed solution) was 25°C or lower, and the reaction was carried out with reflux dehydration for 4 hours. Then, it was allowed to cool, methanol (120.4 g) was added at 60°C, it was allowed to cool to 55°C, heated at 55°C for 1 hour for dispersion washing, then gradually cooled, held at 10°C or lower for 1 hour, and the precipitated crystals were filtered. By pouring cold methanol over the filtered crystals for rinsing, 348.3 g of crude methyl 6-hydroxy-2-naphthoate containing methanol and sulfuric acid (HPLC purity 99.3 area%) was obtained.

[0159] [Coupling step] The obtained crude methyl 6-hydroxy-2-naphthoate (343.8 g), N,N-dimethylformamide (826.5 g), N-methyl-2-pyrrolidinone (91.8 g) and copper(I) chloride (11.1 g, 0.1 mol) were dissolved (mixed) at 70°C, and reacted at 70°C for 13 hours while bubbling a mixed gas of nitrogen and oxygen at a rate of 0.2 L / min. The decrease in the remaining amount of the raw material was confirmed by HPLC.

[0160] [Etherification step] 25% by mass (1 / 4 amount) of the obtained reaction solution was taken out, concentrated at 80 °C under 100 torr or less to discharge the solvent (183.7 g), and then MEK (183.7 g) and potassium carbonate (87.4 g, 0.6 mol) were added. While stirring, dimethyl sulfate (76.5 g, 0.6 mol) was added dropwise. Then, the mixture was stirred at 40 °C for 6 hours. After confirming the decrease in the remaining amount of the raw material by HPLC, MEK (276.0 g), toluene (207.0 g), and water (188.2 g) were added and dissolved at 75 °C, and then the aqueous layer was discharged. Then, the organic layer was washed with 1% by mass oxalic acid solution (75.3 g) and then washed with water multiple times. After filtering the organic layer using activated carbon and celite, toluene (94.1 g) and acetonitrile (100.4 g) were added, and cooling crystallization was performed. Crystals were precipitated at 50 °C and aged for 1 hour, then gradually cooled and held at 10 °C or lower for 1 hour, and then the precipitated crystals were filtered. The filtered crystals were rinsed with cold toluene and cold methanol in that order, and then dried under reduced pressure at 120 °C to obtain 53.3 g of 6,6'-bis(methoxycarbonyl)-2,2'-dimethoxy-1,1'-binaphthyl (2,6-BMN-m) (yield 62.0% from 6-hydroxy-2-naphthoic acid, HPLC purity 99.7 area%).

[0161] Table 3 below shows the purity and impurity data of the compounds obtained in Examples 1 to 4. In Example 1, the purity and impurity data of the crude 2,6-BMN-m before purification by column chromatography are also shown for reference. In the table, BMN represents 6,6'-bis(methoxycarbonyl)-2,2'-dihydroxy-1,1'-binaphthyl, the monoether form represents the monomethyl ether of BMN, and the target compound represents 6,6'-bis(methoxycarbonyl)-2,2'-dimethoxy-1,1'-binaphthyl.

[0162]

Table 3

[0163] As is clear from Table 3, in Examples 2 to 4, even without column formation, the concentrations of impurities (unreacted components and monomethyl ether forms) are greatly reduced, and a high-purity compound (1) can be obtained.

[0164] [Comparative Example 2] Into the reactor, as the dicarboxylic acid component, 2,3-BMN-m (10.76 g (25 mmol)) prepared in Comparative Example 1, 9,9-bis(2-methoxycarbonylethyl)fluorene (FDP-m) (8.46 g (25 mmol)), as the diol component, 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]fluorene (BNEF, synthesized according to Synthesis Example 1 described in JP-A-2018-59074) (24.24 g (45 mmol)), ethylene glycol (EG) (6.51 g (105 mmol)), as a catalyst for the transesterification reaction and polycondensation reaction, titanium(IV) tetrabutoxide (5.1 mg (15 μmol)) and calcium acetate monohydrate (4.4 mg (25 μmol)) were charged, and the mixture was gradually heated to 250 °C and stirred under a nitrogen atmosphere to conduct the transesterification reaction. After removing the alcohol component generated by the transesterification reaction, dibutylphosphoric acid (15.8 mg (75 μmol)) was added as a heat stabilizer, and the temperature was gradually raised to 285 °C and the pressure was reduced to 150 Pa, and the polycondensation reaction was carried out while removing EG until a predetermined stirring torque was reached. After the reaction was completed, the content was taken out of the reactor to obtain a polyester resin.

[0165] [Example 5] Into the reactor, as the dicarboxylic acid component, 2,6-BMN-m (8.61 g (20 mmol)) prepared in Example 2, FDP-m (6.77 g (20 mmol)), as the diol component, BNEF (19.38 g (36 mmol)), EG (5.22 g (84 mmol)), as a catalyst for the transesterification reaction and polycondensation reaction, titanium(IV) tetrabutoxide (2.7 mg (8 μmol)) was charged, and the mixture was gradually heated to 250 °C and stirred under a nitrogen atmosphere to conduct the transesterification reaction. After removing the alcohol component generated by the transesterification reaction, dibutylphosphoric acid (12.6 mg (60 μmol)) was added as a heat stabilizer, and the temperature was gradually raised to 285 °C and the pressure was reduced to 120 Pa, and the polycondensation reaction was carried out while removing EG until a predetermined stirring torque was reached. After the reaction was completed, the content was taken out of the reactor to obtain a polyester resin.

[0166] Composition ([ 1 1 mol %) and properties of the polyester resins obtained in Comparative Example 2 and Example 5 are shown in Table 4.

[0167]

Table 4

[0168] As is clear from Table 4, compared with the comparative examples, the polyester resin obtained in the examples showed a high refractive index and a low Abbe number without much increase in birefringence, and also showed a high Tg.

Industrial Applicability

[0169] The compound (1) produced by the present invention can be used as a raw material such as a reagent or an additive. In particular, since the compound (1) has a high refractive index and high heat resistance, it is useful as a polymerization component for preparing resins such as polyester resins.

Claims

1. A method for producing a bisnaphthoic acid derivative represented by the following formula (1), which includes an etherification step of etherifying a compound represented by the following formula (2) with an etherifying agent. 【Chemical 1】 (wherein, R １ａ and R １ｂ independently represent a hydrocarbon group, R ２ａ and R ２ｂ independently represent a halogen atom, a hydrocarbon group, a group -ORh (wherein, Rh represents a hydrocarbon group), a group -SRh (wherein, Rh represents a hydrocarbon group), an acyl group, a nitro group, a cyano group or a substituted amino group, k1 and k2 independently represent an integer of 0 to 5, R ３ａ and R ３ｂ independently represent an alkoxy group)

2. In the formula (1), R １ａ and R １ｂ are alkyl groups, R ２ａ and R ２ｂ are halogen atoms or alkyl groups, and k1 and k2 are integers from 0 to 2. The method for producing a bisnaphthoic acid derivative according to claim 1.

3. In the formula (1), R １ａ and R １ｂ are alkyl groups having 1 to 4 carbon atoms, R ２ａ and R ２ｂ are halogen atoms or alkyl groups having 1 to 4 carbon atoms, k1 and k2 are 0 or 1, R ３ａ and R ３ｂ are alkoxy groups having 1 to 4 carbon atoms, The method for producing a bisnaphthoic acid derivative according to claim 1 or 2.

4. The method for producing a bisnaphthoic acid derivative according to any one of claims 1 to 3, further including a recovery step of removing impurities from the reaction mixture obtained in the etherification step and recovering the compound represented by the formula (1) as crystals.

5. The method for producing a bisnaphthoic acid derivative according to any one of claims 1 to 4, further including a coupling step of preparing the compound represented by the formula (2) by coupling the compounds represented by the following formulas (3a) and (3b). 【Chemical Formula 2】 (wherein, R ２ａ and R ２ｂ , k1 and k2, and R ３ａ and R ３ｂ are the same as those described above)

6. The method for producing a bisnaphthoic acid derivative according to claim 5, further including an esterification step of preparing the compounds represented by the formulas (3a) and (3b) by esterifying the compounds represented by the following formulas (4a) and (4b). [Chemical Formula 3] (wherein, R ２ａ and R ２ｂ , k1 and k2 are the same as described above)

7. The esterification step is an esterification step of reacting the compounds represented by the formulas (4a) and (4b) with alcohols represented by the formulas (5a) and (5b): R ３ａ H (5a) R ３ｂ H (5b) (R ３ａ and R ３ｂ are the same as those described above) in the presence of an acid catalyst to obtain a reaction mixture, and the method for producing a bisnaphthoic acid derivative according to claim 6, further including a separation and purification step of crystallizing the reaction mixture obtained in the esterification step to obtain the compounds represented by the formulas (3a) and (3b).

8. In the esterification step, the acid catalyst is a soluble acid catalyst, and in the separation and purification step, a poor solvent is added to the reaction mixture for crystallization. The method for producing a bisnaphthoic acid derivative according to claim 6 or 7.

9. In the coupling step, the method for producing a bisnaphthoic acid derivative according to any one of claims 5 to 8, which is a step of oxidatively coupling the compounds represented by the formulas (3a) and (3b) in an organic solvent in the presence of a copper salt.

10. In the coupling step, the method for producing a bisnaphthoic acid derivative according to claim 9, wherein the organic solvent is a nitrogen-containing aprotic polar solvent.

11. In the etherification step, etherify with an etherifying agent in the presence of a base, dissolve the crystallized product from the reaction mixture in an organic solvent, subject the obtained organic solvent solution to an adsorption treatment with an adsorbent, and then crystallize the compound represented by the formula (1) from the organic solvent solution. The production method according to any one of claims 1 to 10.

12. A crystal of a bisnaphthoic acid derivative represented by the following formula (1). 【Chemical Formula 4】 (wherein, R １ａ and R １ｂ each independently represents a linear or branched alkyl group having 1 to 5 carbon atoms, and R ２ａ and R ２ｂ each independently represents a halogen atom, a hydrocarbon group, a group -ORh (wherein Rh represents a hydrocarbon group), a group -SRh (wherein Rh represents a hydrocarbon group), an acyl group, a nitro group, a cyano group or a substituted amino group, k1 and k2 each independently represent an integer of 0 to 5, and R ３ａ and R ３ｂ each independently represents an alkoxy group)

13. In the formula (1), the R ３ａ and R ３ｂ are independently a linear or branched alkoxy group having 1 to 6 carbon atoms, and the crystal of the bisnaphthoic acid derivative according to claim 12.

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