JP7731682B2 - Dicarboxylic acids and their production method - Google Patents

Description

The present invention relates to a novel dicarboxylic acid or derivative thereof having a fluorene skeleton, and a method for producing the same.

Dicarboxylic acids and their derivatives (dicarboxylic acids) exhibit high refractive indices and heat resistance, and are therefore used as resin raw materials and additives (or resin additives) such as refractive index improvers and heat resistance improvers. In particular, dicarboxylic acids with a fluorene skeleton are used as materials in the optical field due to their high refractive index and heat resistance.

Patent Document 1 discloses that dicarboxylic acids with a specific chemical structure in which aryl groups are bonded to positions 1 to 8 of the fluorene skeleton have excellent optical properties and heat resistance, and that when used as a polymerization component, they can surprisingly form resins with significantly superior properties, despite not having aryl groups at the 9,9-positions that tend to improve refractive index and glass transition temperature. In the examples in this document, naphthyl groups are listed as the aryl groups bonded to positions 1 to 8 of the fluorene skeleton.

WO2020/213470

However, in recent years, in the optical field, as optical devices such as cameras and image display devices have become more sophisticated, there is a demand for advanced heat resistance and optical properties, and even the dicarboxylic acids described in Patent Document 1 may not be sufficient.

Accordingly, the object of the present invention is to provide novel dicarboxylic acids with excellent heat resistance and optical properties, and a method for producing the same.

As a result of extensive research to achieve the above-mentioned objectives, the inventors discovered that a novel dicarboxylic acid with a specific chemical structure in which fused tetra- to hexacyclic aryl groups are bonded to positions 1 to 8 of the fluorene skeleton has excellent heat resistance and optical properties, leading to the completion of the present invention.

That is, the dicarboxylic acid or derivative thereof of the present invention is a dicarboxylic acid or derivative thereof represented by the following formula (I):

(In the formula,
ring Z ^1a and ring Z ^1b may be the same or different and represent a fused tetra- to hexacyclic arene ring;
R ^1a and R ^1b are the same or different and represent a substituent;
k1 and k2 are the same or different and each represent an integer of 0 or more,
A ^1a and A ^1b are the same or different and each represent a linear or branched alkylene group;
R ^2a and R ^2b are the same or different and represent a substituent;
n1 and n2 may be the same or different and represent an integer of 0 to 3.

In the formula (I), Z ^1a and Z ^1b may be pyrene rings, A ^1a and A ^1b may be linear or branched C _2-6 alkylene groups, Z ^1a and Z ^1b may be substituted at the 2,7-positions of the fluorene ring, A ^1a and A ^1b may be linear or branched C _2-4 alkylene groups, and k1, k2, n1, and n2 may be 0.

The present invention also includes a method for producing the dicarboxylic acid or a derivative thereof, which comprises a step of coupling reaction of a compound having a fluorene skeleton with a compound having a fused tetra- to hexacyclic arene ring skeleton corresponding to rings ^Z1a and Z1b in formula (I ⁾ .

In this specification and claims, the term "derivative" of a dicarboxylic acid is used to mean not only ester (or amide)-forming derivatives such as dicarboxylic acid esters, dicarboxylic acid halides, and dicarboxylic acid anhydrides, but also compounds that can be converted from dicarboxylic acids using conventional methods, such as dicarboxylic acid amides and dicarboxylic acid salts.

Examples of the dicarboxylic acid esters include alkyl esters of dicarboxylic acid components, particularly lower alkyl esters, such as _C1-4 alkyl esters such as methyl ester, ethyl ester, and t-butyl ester. Examples of the dicarboxylic acid halides include dicarboxylic acid chlorides and dicarboxylic acid bromides. Examples of the dicarboxylic acid salts include metal salts, specifically alkali metal salts such as sodium salts, and ammonium salts.

Furthermore, in this specification and claims, the number of carbon atoms in a substituent may be indicated as C ₁ , C ₆ , C ₁₀ , etc. For example, a "C ₁ alkyl group" means an alkyl group having one carbon atom, and a "C _6-10 aryl group" means an aryl group having 6 to 10 carbon atoms.

In this invention, a novel dicarboxylic acid or its derivative having a specific chemical structure in which fused tetra- to hexacyclic aryl groups are bonded to positions 1 to 8 of the fluorene skeleton has excellent heat resistance and optical properties.

[Dicarboxylic acid or its derivative]
The novel dicarboxylic acid or derivative thereof (dicarboxylic acids) of the present disclosure is a dicarboxylic acid or derivative thereof represented by the above formula (I).

In the formula (I), examples of the fused tetracyclic to hexacyclic arene rings represented by Z ^1a and Z ^1b include fused tetracyclic C _16-18 arene rings such as a fluoranthene ring, an acephenanthrylene ring, an aceanthrylene ring, a triphenylene ring, a pyrene ring, a chrysene ring, a tetraphene ring, and a tetracene ring (naphthacene ring); fused pentacyclic C _20-22 arene rings such as a picene ring, a perylene ring, a pentaphene ring, and a pentacene ring; and fused hexacyclic C _24-28 arene rings such as a hexahelicene ring, a hexaphene ring, and a hexacene ring. Of these, from the viewpoint of excellent heat resistance and optical properties, fused tetracyclic arene rings are preferred, fused tetracyclic C _16-18 arene rings are more preferred, and a pyrene ring is most preferred. The type of ring Z ^1a and the type of ring Z ^1b may be different from each other, but are preferably the same.

The rings Z ^1a and Z ^1b may be substituted at any of the 1- to 4-positions and the 5- to 8-positions of the fluorene skeleton, but are preferably symmetrically positioned on the paper in formula (I), such as the 1,8-positions, the 2,7-positions, the 3,6-positions, or the 4,5-positions, and are particularly preferably the 2,7-positions. When ^{Z 1a} and Z ^1b are pyrene rings, the 1- or 2-position of the pyrene ring is preferably bonded to the fluorene ring, and it is particularly preferred that the 1-position of the pyrene ring is bonded to the fluorene ring.

Examples of the substituents (non-reactive substituents or non-polymerizable substituents) represented by R ^1a and R ^1b include a halogen atom, a hydrocarbon group (or group [-R ^A ]), a group [-OR ^A ] (wherein R ^A represents the hydrocarbon group), a group [-SR ^A ] (wherein R ^A represents the hydrocarbon group), an acyl group, a nitro group, a cyano group, and a mono- or di-substituted amino group.

Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

Examples of the hydrocarbon group represented by R 1 ^A include an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group.

Examples of the alkyl group include a linear or branched C _1-10 alkyl group such as a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, and t-butyl group, and are preferably a linear or branched C _1-6 alkyl group, and more preferably a linear or branched C _1-4 alkyl group.

Examples of the cycloalkyl group include a C _5-10 cycloalkyl group such as a cyclopentyl group and a cyclohexyl group.

Examples of the aryl group include C _6-12 aryl groups such as phenyl group, alkylphenyl group, biphenylyl group, naphthyl group, etc. Examples of the alkylphenyl group include mono- to tri-C _1-4 alkyl-phenyl groups such as methylphenyl group (or tolyl group) and dimethylphenyl group (or xylyl group).

Examples of the aralkyl group include a C _6-10 aryl-C _1-4 alkyl group such as a benzyl group or a phenethyl group.

Examples of the group [-OR ^A ] include an alkoxy group, a cycloalkyloxy group, an aryloxy group, and an aralkyloxy group, and specific examples include groups corresponding to the examples of the hydrocarbon group R ^A. Examples of the alkoxy group include linear or branched C _1-10 alkoxy groups such as methoxy, ethoxy, propoxy, n-butoxy, isobutoxy, and t-butoxy. Examples of the cycloalkyloxy group include C 5-10 cycloalkyloxy groups such as cyclohexyloxy. Examples of the aryloxy group include C _6-10 aryloxy groups such as phenoxy. Examples of the aralkyloxy group include _{C 6-10 aryl} -C _1-4 alkyloxy groups such as benzyloxy.

Examples of the group [—SR ^A ] include alkylthio groups, cycloalkylthio groups, arylthio groups, and aralkylthio groups, and specific examples include groups corresponding to the examples of the hydrocarbon group R ^A. Examples of alkylthio groups include C _1-10 alkylthio groups such as methylthio groups, ethylthio groups, propylthio groups, n-butylthio groups, and t-butylthio groups. Examples of cycloalkylthio groups include C _5-10 cycloalkylthio groups such as cyclohexylthio groups. Examples of arylthio groups include C _6-10 arylthio groups such as thiophenoxy groups. Examples of aralkylthio groups include C _6-10 aryl-C _1-4 alkylthio groups such as benzylthio groups.

Examples of the acyl group include a C _1-6 alkyl-carbonyl group such as an acetyl group.

Examples of mono- or di-substituted amino groups include dialkylamino groups and bis(alkylcarbonyl)amino groups. Examples of dialkylamino groups include di-C _1-4 alkylamino groups such as dimethylamino groups. Examples of bis(alkylcarbonyl)amino groups include bis(C _1-4 alkyl-carbonyl)amino groups such as diacetylamino groups.

Representative examples of these groups R ^1a and R ^1b include hydrocarbon groups, alkoxy groups, acyl groups, nitro groups, cyano groups, and substituted amino groups. When k1 or k2 is 1 or greater, preferred groups R ^1a and R ^1b are alkyl groups and alkoxy groups, specifically linear or branched C _1-6 alkyl groups such as methyl groups, and linear or branched C _1-4 alkoxy groups such as methoxy groups. Of these, alkyl groups, particularly linear or branched C _1-4 alkyl groups such as methyl groups, are preferred. When group R ^1a or R ^1b is an aryl group, group R ^1a or R ^1b may form the ring-assembly arene ring together with ring Z ^1a or Z ^1b , respectively.

The substitution numbers k1 and k2 may be selected depending on the types of rings ^Z1a and ^Z1b , and can be selected, for example, from integers of about 0 to 12. Preferred ranges are, in the following stepwise order, integers of 0 to 6, integers of 0 to 5, integers of 0 to 4, integers of 0 to 3, and integers of 0 to 2, more preferably 0 or 1, and particularly preferably 0.

The substitution numbers k1 and k2 of the groups R ^1a and R ^1b may be different from each other, but are usually the same in many cases. When the substitution number k1 or k2 is 2 or more, the types of the two or more groups R ^1a or R ^1b substituting on the same ring Z ^1a or Z ^1b may be the same or different from each other. Furthermore, the types of the groups R ^1a and R ^1b substituting on different rings Z ^1a and Z ^1b may be different from each other, but are usually the same in many cases. The substitution positions of the groups R ^1a and R ^1b are not particularly limited and may be selected depending on the types of rings Z ^1a and Z ^1b .

The substituents (non-reactive substituents or non-polymerizable substituents) represented by R ^2a and R ^2b may be any substituent other than the group [-Z ^1a -(R ^1a ) _k1 ] and the group [-Z ^1b -(R ^1b ) _k2 ] (hereinafter, these may also be referred to as ^Z1- containing groups), and representative examples include hydrocarbon groups such as alkyl groups (excluding aryl groups), halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms, and cyano groups. Examples of alkyl groups include linear or branched C _1-6 alkyl groups such as methyl groups, ethyl groups, and t-butyl groups. When the number of substitutions n1 or n2 is 1 or more, preferred R ^2a and R ^2b are linear or branched C _1-4 alkyl groups such as methyl groups.

The substitution numbers n1 and n2 of R ^2a and R ^2b are, for example, integers of about 0 to 3, preferably integers of 0 to 2, more preferably 0 or 1, and particularly 0. n1 and n2 may be different from each other, but are usually the same in many cases. When n1 or n2 is 2 or more, the types of R ^2a or R ^2b substituted on the same benzene ring among the two benzene rings forming the fluorene skeleton may be the same or different from each other. Furthermore, the types of R ^2a and R ^2b substituted on different benzene rings among the two benzene rings forming the fluorene skeleton may be the same or different from each other, but are usually the same in many cases. Furthermore, the substitution positions of R ^2a and R ^2b are not particularly limited, as long as they are substituted at positions other than the substitution position of the ^Z1- containing group.

Examples of the linear or branched alkylene group represented by groups A ^1a and A ^1b include linear or branched C _1-8 alkylene groups such as methylene, ethylene, trimethylene, propylene, 1,2-butanediyl, and 2-methylpropane-1,3-diyl. Preferred alkylene groups include linear or branched C _1-6 alkylene groups such as methylene, ethylene, trimethylene, propylene, and 2-methylpropane-1,3-diyl, more preferably linear or branched C _1-4 alkylene groups, and even more preferably linear or branched C _2-4 alkylene groups. Of these, linear or branched C _2-3 alkylene groups such as ethylene and propylene are preferred, with ethylene being particularly preferred.

Examples of dicarboxylic acids represented by formula (I) include 9,9-bis(carboxy C 2-6 alkyl)-dipyrenylfluorenes such as 9,9-bis(2-carboxyethyl)-1,8-di(1-pyrenyl)fluorene, 9,9-bis(2-carboxyethyl)-2,7-di(1-pyrenyl)fluorene, 9,9-bis(2-carboxyethyl)-3,6-di(1-pyrenyl)fluorene, 9,9-bis(2-carboxyethyl)-4,5-di(1-pyrenyl)fluorene, 9,9-bis(2-carboxypropyl)-2,7-di(1-pyrenyl)fluorene, and 9,9-bis(2-carboxyethyl) _-2,7 -di(2-pyrenyl)fluorene. Of these, 9,9-bis(2-carboxyethyl)-2,7-di(1-pyrenyl)fluorene is preferred.

The dicarboxylic acid represented by formula (I) or its derivative has a high refractive index and high heat resistance.

The 5% mass loss temperature of the dicarboxylic acid represented by formula (I) or its derivative may be, for example, approximately 350 to 500°C, with preferred ranges being 370 to 480°C, 390 to 470°C, 400 to 460°C, 410 to 450°C, 420 to 440°C, and 430 to 435°C, in the following stepwise order.

In this specification and claims, the 5% mass loss temperature of the dicarboxylic acid represented by formula (I) or its derivative can be measured by the method described in the examples below.

[Method of producing dicarboxylic acid or its derivative]
The method for producing the dicarboxylic acid or derivative thereof (dicarboxylic acids) of the present disclosure is not particularly limited, and the dicarboxylic ^acid or derivative thereof (dicarboxylic acids ⁾ may be produced by a conventional method, for example, a method comprising at least a step of coupling a compound having a fluorene skeleton with a compound having a fused tetra- to hexacyclic arene ring skeleton corresponding to rings Z1a and Z1b in formula (I) to introduce a fused tetra- to hexacyclic aryl group corresponding to the compound having the fused tetra- to hexacyclic arene ring skeleton into at least one substitution position selected from positions 2 to 8 of the fluorene skeleton. More specifically, the dicarboxylic acid or derivative thereof may be produced by coupling a dicarboxylic acid represented by formula (II) below with compounds represented by formulas (IIIa) and (IIIb) below (hereinafter also referred to as a first production method) according to the following reaction scheme:

(In the formula, X ^1a and X ^1b each independently represent a reactive group capable of forming a carbon-carbon bond (or a direct bond) by a coupling reaction; X ^2a and X ^2b each represent a reactive group capable of forming a carbon-carbon bond together with the reactive group X ^1a and the reactive group X ^1b by a coupling reaction; Z ^1a , Z ^1b , R ^1a , R ^1b , k1, k2, R ^2a , R ^2b , n1, n2, A ^1a and A ^1b each represent the same as those in formula (I) above, including preferred embodiments.)

The coupling reaction is not particularly limited and includes conventional coupling reactions, such as palladium-catalyzed (or palladium(0)) coupling reactions such as the Suzuki-Miyaura coupling reaction, Migita-Kosugi-Stille coupling reaction, Negishi coupling reaction, and Hiyama coupling reaction, and nickel-catalyzed (or nickel(0)) coupling reactions such as the Kumada-Tamao-Corriu coupling reaction. Of these coupling reactions, the Suzuki-Miyaura coupling reaction is frequently used.

The reactive groups X ^1a and X ^1b , as well as X ^2a and X ^2b , can be appropriately selected depending on the type of coupling reaction. When synthesis is performed by the Suzuki-Miyaura coupling reaction, one of the reactive groups, for example, groups X ^1a and X ^1b , can be a halogen atom or a fluorinated alkane sulfonyloxy group. Examples of halogen atoms include an iodine atom, a bromine atom, and a chlorine atom. Examples of fluorinated alkane sulfonyloxy groups include fluorinated C _1-4 alkanesulfonyloxy groups such as a trifluoromethanesulfonyloxy group (or group [-OTf]).

These one-reactive groups may be used alone or in combination of two or more. Of these one-reactive groups, halogen atoms are preferred, with iodine and bromine atoms being more preferred, and bromine atoms are typically used most frequently.

In the Suzuki-Miyaura coupling reaction, examples of the other reactive group capable of coupling with one of the reactive groups, such as groups ^X2a and ^X2b , include boronic acid groups (dihydroxyboryl groups or groups [—B(OH) ₂ ]) and boronate ester groups. Examples of the boronate ester groups include dialkoxyboryl groups such as dimethoxyboryl groups, diisopropoxyboryl groups, and dibutoxyboryl groups; and cyclic boronate ester groups such as pinacolatoboryl groups (or groups [-Bpin]), 1,3,2-dioxaborinan-2-yl groups, and 5,5-dimethyl-1,3,2-dioxaborinan-2-yl groups.

These other reactive groups may be used alone or in combination of two or more.Of the other reactive groups, the group [-B(OH) ₂ ] is usually used frequently.

The groups ^X1a and ^X1b and the groups ^X2a and ^X2b may be any pair of reactive groups capable of undergoing a coupling reaction with each other, and the groups ^X1a and ^X1b may be the other reactive group such as a boronic acid group, and the groups ^X2a and ^X2b may be one reactive group such as a halogen atom. However, it is usually the case that the groups ^X1a and ^X1b are one reactive group such as a halogen atom, and the group ^X2 is the other reactive group such as a boronic acid group.

The dicarboxylic acid represented by formula (II) or a derivative thereof is usually often the dicarboxylic acid ester exemplified above as the ester-forming derivative, etc. Specific examples of the dicarboxylic acid represented by formula (II) or a derivative thereof include compounds corresponding to preferred embodiments of the dicarboxylic acid represented by formula (I), such as 9,9-bis(C _1-4 alkoxy-carbonyl-C _2-6 alkyl)-dihalofluorenes such as 9,9-bis(2-methoxycarbonylethyl)-2,7-dibromofluorene, 9,9-bis(2-ethoxycarbonylethyl)-2,7-dibromofluorene, and 9,9-bis(2-methoxycarbonylpropyl)-2,7-dibromofluorene.

The dicarboxylic acid represented by formula (II) or its derivative may be prepared, for example, according to the method described in JP-A-2005-89422. Specifically, it may be prepared by reacting a 9H-fluorene unsubstituted at the 9-position, such as 2,7-dibromofluorene, with an acrylic acid ester, such as methyl acrylate, or a haloacetic acid ester, such as methyl bromoacetate, in the presence of a base catalyst, such as trimethylbenzylammonium hydroxide.

The compounds represented by formulas (IIIa) and (IIIb) include compounds corresponding to preferred embodiments of the dicarboxylic acid represented by formula (I), such as 1-pyrenylboronic acid and 2-pyrenylboronic acid, with 1-pyrenylboronic acid being preferred. It is preferable that the compounds represented by formulas (IIIa) and (IIIb) are the same compound. The compounds represented by formulas (IIIa) and (IIIb) can be commercially available products.

The ratio of the dicarboxylic acid or derivative thereof represented by formula (II) to the total amount of the compounds represented by formulas (IIIa) and (IIIb) may be, for example, a former/latter (molar ratio) of about 1/2 to 1/10, with preferred ranges being 1/2.2 to 1/8, 1/2.5 to 1/5, and 1/2.7 to 1/3.3, in the following stepwise order.

When synthesizing by the Suzuki-Miyaura coupling reaction, the reaction is usually carried out in the presence of a palladium catalyst. Examples of palladium catalysts include conventional coupling catalysts such as palladium(0) catalysts and palladium(II) catalysts.

Examples of palladium(0) catalysts include palladium(0)-phosphine complexes such as tetrakis(triphenylphosphine)palladium(0) [or Pd(PPh ₃ ) ₄ ] and bis(tri-t-butylphosphine)palladium(0) [or Pd(P(t-Bu) ₃ ) ₂ ].

Examples of the palladium(II) catalyst include palladium(II)-phosphine complexes such as [1,2-bis(diphenylphosphino)ethane]palladium(II) dichloride [or PdCl ₂ (dppe)], [1,3-bis(diphenylphosphino)propane]palladium(II) dichloride [or PdCl ₂ (dppp)], [1,1′-bis(diphenylphosphino)ferrocene]palladium(II) dichloride [or PdCl ₂ (dppf)], bis(triphenylphosphine)palladium(II) dichloride [or PdCl ₂ (PPh ₃ ) ₂ ], and bis(tri-o-tolylphosphine)palladium(II) dichloride [or PdCl ₂ (P(o-tolyl) ₃ ) ₂ ]. When a palladium (II) catalyst is used, the reaction starts when the palladium (II) catalyst is reduced to a zero-valent complex by a reducing compound in the reaction system, such as a phosphine, an amine, or an organometallic reagent.

The palladium catalyst may be prepared in situ by adding a catalyst precursor such as tris(dibenzylideneacetone)dipalladium(0) chloroform complex [or Pd ₂ (dba) _{3.CHCl 3} ] and a ligand such as a phosphine or a carbene.

These catalysts can be used alone or in combination of two or more. Among these catalysts, palladium(0)-phosphine complexes such as Pd(PPh ₃ ) ₄ are commonly used. The proportion of the catalyst, in terms of metal, may be, for example, about 0.01 to 0.1 moles, and preferably 0.03 to 0.07 moles, per mole of the dicarboxylic acid represented by formula (II) or its derivative.

The Suzuki-Miyaura coupling reaction may be carried out in the presence of a base. Examples of bases include metal carbonates or hydrogen carbonates, metal hydroxides, metal fluorides, metal phosphates, metal organic acid salts, and metal alkoxides.

Examples of metal carbonates or bicarbonates include alkali metal carbonates or bicarbonates such as sodium carbonate, potassium carbonate, cesium carbonate, and sodium bicarbonate, as well as thallium(I) carbonate.

Examples of metal hydroxides include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and cesium hydroxide, alkaline earth metal hydroxides such as barium hydroxide, and thallium(I) hydroxide.

Examples of metal fluorides include alkali metal fluorides such as potassium fluoride and cesium fluoride.

Examples of metal phosphates include alkali metal phosphates such as tripotassium phosphate.

Examples of metal organic acid salts include alkali metal acetates such as potassium acetate.

Examples of metal alkoxides include alkali metal alkoxides such as sodium methoxide, sodium ethoxide, and potassium t-butoxide.

These bases can be used alone or in combination of two or more. Metal carbonates such as potassium carbonate are commonly used. The ratio of the base may be, for example, about 0.1 to 50 moles, and preferably 1 to 25 moles, per mole of the dicarboxylic acid represented by formula (II) or its derivative.

The coupling reaction may be carried out in the presence or absence of a phase transfer catalyst. Examples of phase transfer catalysts include tetraalkylammonium halides such as tetrabutylammonium bromide (TBAB) and trioctylmethylammonium chloride. These phase transfer catalysts can be used alone or in combination. Of these phase transfer catalysts, TBAB is commonly used.

The coupling reaction may be carried out in the absence or presence of a reaction-inert solvent. Examples of solvents include water; alcohols such as methanol and ethanol; ethers such as cyclic ethers and chain ethers; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; nitriles such as acetonitrile and benzonitrile; amides such as N,N-dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxides such as dimethyl sulfoxide; and hydrocarbons such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons.

Examples of cyclic ethers include dioxane and tetrahydrofuran. Examples of chain ethers include dialkyl ethers such as diethyl ether and diisopropyl ether, and glycol ethers. Examples of glycol ethers include (poly)alkylene glycol monoalkyl ethers such as methyl cellosolve and methyl carbitol, and (poly)alkylene glycol dialkyl ethers such as dimethoxyethane.

Aliphatic hydrocarbons include, for example, hexane and dodecane. Alicyclic hydrocarbons include, for example, cyclohexane. Aromatic hydrocarbons include, for example, toluene and xylene.

These solvents can be used alone or in combination. Among these solvents, a mixed solvent of water and a chain ether such as dimethoxyethane is commonly used.

The coupling reaction may be carried out under an inert gas atmosphere, such as nitrogen or a rare gas such as helium or argon. The reaction temperature is, for example, 50 to 200°C, preferably 60 to 100°C. The reaction time is not particularly limited and may be, for example, about 1 to 10 hours.

After the reaction is complete, the reaction mixture may be separated and purified, if necessary, by conventional separation and purification methods, such as washing, extraction, filtration, dehydration, concentration, decantation, recrystallization, reprecipitation, chromatography, or a combination of these.

Furthermore, the dicarboxylic acid represented by formula (I) or its derivative may be produced into a compound represented by formula (I) by a second production method shown in the following reaction scheme.

(In the formula, X ^1a , X ^1b , X ^2a and X ^2b are the same as those in the formulae (II), (IIIa) and (IIIb) above, including preferred embodiments, and Z ^1a , Z ^1b , R ^1a , R ^1b , k1, k2, R ^2a , R ^2b , n1, n2, A ^1a and A ^1b are each the same as those in the formula (I) above, including preferred embodiments.)

In the second production method, instead of the dicarboxylic acid represented by formula (II) or its derivative in the first production method, a 9H-fluorene represented by formula (IV) is used to couple the compound represented by formula (IIIa) and the compound represented by formula (IIIb), and the resulting compound represented by formula (V) is used as a 9H-fluorene unsubstituted at the 9-position in the method described in the aforementioned JP-A No. 2005-89422 to produce the compound represented by formula (I). That is, in the second production method, the order of introduction of the A ^1a or A ^1b- containing group substituting the 9-position of the fluorene skeleton and the Z ^1- containing group is different from that in the first production method.

The 9H-fluorenes represented by formula (IV) include 9H-fluorenes that have a coupling-capable reactive group and are unsubstituted at the 9-position, such as dihalofluorenes such as 2,7-dibromofluorene. The compound represented by formula (IV) may be a commercially available product.

The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

Comparative Example 1
9,9-bis(2-methoxycarbonylethyl)-2,7-dibromofluorene (DBrFDP-m) was synthesized in the same manner as in Example 1 of JP 2005-89422 A, except that methyl acrylate [37.9 g (0.44 mol)] was used instead of t-butyl acrylate and 2,7-dibromo-9H-fluorene [54.7 g (0.17 mol)] was used instead of fluorene.

A reactor was charged with 192.3 g (0.39 mol) of DBrFDP-m, 200 g (1.2 mol) of 2-naphthylboronic acid, 4.3 L of dimethoxyethane, and 1 L of 2 M aqueous sodium carbonate solution. Under a nitrogen stream, 22.4 g (19.4 mmol) of tetrakis(triphenylphosphine)palladium(0) [or Pd(PPh ₃ ) ₄ ] was added, and the mixture was heated to reflux at an internal temperature of 71-78°C for 5 hours to allow the reaction to proceed. After cooling to room temperature, 2.0 L of toluene and 500 mL of ion-exchanged water were added, and the mixture was washed by extraction five times. The organic layer changed from deep orange to brown. Insoluble matter was filtered off and concentrated, yielding 305 g of crude brown crystals. The obtained crude crystals were heated and dissolved in a mixture of 1.5 kg of ethyl acetate and 300 g of isopropyl alcohol (IPA), then cooled to 10 ° C or below with ice water and stirred for 1 hour to precipitate crystals. The precipitated crystals were filtered and dried under reduced pressure to obtain 130 g of gray-brown crystals. The obtained gray-brown crystals were purified by column chromatography (silica gel carrier, developing solvent chloroform: ethyl acetate (volume ratio) = 4:1), then recrystallized with methanol and dried under reduced pressure to obtain 116 g of 9,9-bis(2-methoxycarbonylethyl)-2,7-di(2-naphthyl)fluorene (2,7-DNFDP-m) represented by the following formula (white crystals, yield 54.9%).

Example 1
By the same method as in Comparative Example 1 except for using 1-pyrenylboronic acid instead of 2-naphthylboronic acid, 5.5 g of 9,9-bis(2-methoxycarbonylethyl)-2,7-di(1-pyrenyl)fluorene (2,7-DPyFDP-m) represented by the following formula (white crystals, yield 36.8%) was obtained.

Comparative Example 2
By the same method as in Comparative Example 1 except for using phenylboronic acid instead of 2-naphthylboronic acid, 119.7 g of 9,9-bis(2-methoxycarbonylethyl)-2,7-diphenylfluorene (2,7-DPFDP-m) represented by the following formula (white crystals, yield 80.1%) was obtained.

The 5% mass loss temperatures of the dicarboxylic acids obtained in Comparative Examples 1 and 2 and Example 1 were measured using the method described below, and the results are shown in Table 1.

(5% mass loss temperature)
Using a thermogravimetry-differential thermal analyzer (TG-DTA) ("TG/DTA6200" manufactured by SII NanoTechnology Inc.), the temperature at which the mass of the sample decreased by 5% by mass was measured under conditions of a nitrogen atmosphere and a heating rate of 10°C/min.

As is clear from the results in Table 1, the dicarboxylic acids of the examples had better heat resistance than the dicarboxylic acids of the comparative examples.

The dicarboxylic acids of the present invention exhibit high refractive indexes and heat resistance, and can therefore be effectively used as resin raw materials or as additives (or resin additives) such as refractive index improvers and heat resistance improvers.

Claims (4)

The following formula (I)
(In the formula,
ring Z ^1a and ring Z ^1b may be the same or different and represent a fused tetra- to hexacyclic arene ring;
R ^1a and R ^1b are the same or different and represent a substituent;
k1 and k2 represent 0,
A ^1a and A ^1b are the same or different and each represent a linear or branched alkylene group;
R ^2a and R ^2b are the same or different and represent a substituent;
n1 and n2 are the same or different and represent an integer of 0 to 3.
or a derivative thereof ,
A dicarboxylic acid or a derivative thereof, wherein the derivative is a dicarboxylic acid ester, a dicarboxylic acid halide, a dicarboxylic acid anhydride, a dicarboxylic acid amide or a dicarboxylic acid salt . 2. The dicarboxylic acid or derivative thereof according to claim 1, wherein in said formula (I), Z ^1a and Z ^1b are pyrene rings, and A ^1a and A ^1b are linear or branched C _2-6 alkylene groups. 3. The dicarboxylic acid or derivative thereof according to claim 1, wherein Z ^1a and Z ^1b are substituted at the 2- and 7-positions of the fluorene ring, A ^1a and A ^1b are linear or branched C _2-4 alkylene groups, and n1 and n2 are 0. 4. A method for producing the dicarboxylic acid or a derivative thereof according to claim 1, comprising a step of coupling a compound having a fluorene skeleton with a compound having a fused tetra- to hexacyclic arene ring skeleton corresponding to rings Z ^1a and Z ^1b in formula (I).