Method for producing a compound having a binaphthalene skeleton and a compound having a binaphthalene skeleton

Abstract

To provide a method for producing a binaphthalene compound of high purity and excellent hue, at good yields.SOLUTION: The present invention relates to a method for producing 2,2'-bis(2-hydroxyethoxy)-6,6'-diphenyl-1,1'-binaphthalene, by reacting 6,6'-diphenyl-1,1'-bi-2-naphthol with ethylene carbonate in a molar ratio of 1:1.9-1:2.9, and after the finish of the reaction, adding 3 wt.% or more of an alkali aqueous solution to the reaction mixture solution, and heating and stirring them at a temperature higher than or equal to 50°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a compound having a binaphthalene skeleton, and to a compound having a binaphthalene skeleton. [Background technology]

[0002] Resin materials such as polycarbonate, polyester, polyacrylate, polyurethane, and epoxy, which use binaphthalenes such as 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene as raw material monomers, have been attracting attention in recent years as new optical materials for optical lenses, optical sheets, and the like due to their excellent optical properties and heat resistance. It has also been described that compounds substituted at the 6,6'-positions of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene have even better optical properties (Patent Document 1). Patent Document 1 discloses a method for synthesizing 2,2'-bis(2-hydroxyethoxy)-6,6'-diphenyl-1,1'-binaphthalene. While the 2,2'-bis(2-hydroxyethoxy)-6,6'-diphenyl-1,1'-binaphthalene obtained by the synthesis method described in the document is described as being highly pure, the high purity achieved by repeated purification and washing poses a problem of low production yield. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 043060 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a method for producing a binaphthalene compound having high purity and excellent color in a high yield. [Means for solving the problem]

[0005] The present inventors have found that the above problems can be solved by the present invention having the following aspects. <<Aspect 1>> A method for producing a compound represented by formula (2) below by reacting a compound represented by formula (1) below with ethylene carbonate, the method comprising the following steps 1 and 2: Step 1: A step of reacting a compound represented by formula (1) with ethylene carbonate in an amount (molar ratio) of 1:1.9 to 1:2.9 Step 2: After the reaction in Step 1 is completed, a step of adding an alkaline aqueous solution of 3% by weight or more to the reaction mixture solution obtained, and heating and stirring at a temperature of 50°C or higher

[0006] [ka]

[0007] [ka] (In formula (1) and formula (2), X1 to X4 each independently represent an aromatic group having 4 to 36 carbon atoms which may contain a heteroatom and which may have a substituent; n1 and n2 each independently represent an integer of 1 to 4; and n3 and n4 each independently represent an integer of 0 to 2.)

[0008] <<Aspect 2>> A method for producing the compound according to embodiment 1, wherein n1 and n2 in formula (1) and formula (2) are 1, and n3 and n4 are 0.

[0009] Aspect 3 A method for producing the compound according to Aspect 1 or Aspect 2, wherein formula (2) is the following formula (2-A): [ka]

[0010] Aspect 4 A compound represented by the following formula (2-A), in which 0.5 g of the compound represented by the following formula (2-A) is dissolved in 10 ml of dimethylformamide, and the APHA of the solution is 100 or less. [ka] [Effects of the Invention]

[0011] According to the present invention, a binaphthalene compound having high purity and excellent color can be obtained in good yield. DETAILED DESCRIPTION OF THE INVENTION

[0012] <<Method for producing binaphthalene compounds>> (Process 1) In the present invention, a compound represented by the following formula (1) is reacted with a predetermined amount of ethylene carbonate to obtain a compound represented by the following formula (2).

[0013] [ka]

[0014] [ka] (In formula (1) and formula (2), X1 to X4 each independently represent an aromatic group having 4 to 36 carbon atoms which may contain a heteroatom and which may have a substituent; n1 and n2 each independently represent an integer of 1 to 4; and n3 and n4 each independently represent an integer of 0 to 2.)

[0015] X1 to X4 in formula (1) and formula (2) are each independently an aromatic group having 4 to 36 carbon atoms, which may contain a heteroatom, and which may have a substituent. Examples of the aromatic group having 4 to 36 carbon atoms, preferably 5 to 24 carbon atoms, and more preferably 6 to 18 carbon atoms, which may contain a heteroatom, and which may have a substituent include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a phenalenyl group, a fluorenyl group, an acenaphthethylenyl group, an acenaphthenyl group, a biphenylenyl group, an indacenyl group, a pyridyl group, a pyrrolidinyl group, and a thienyl group, with a phenyl group and a naphthyl group being particularly preferred.

[0016] Furthermore, n1 and n2 in formula (1) and formula (2) are each independently an integer of 1 to 4, preferably an integer of 1 or 2, and particularly preferably 1. Furthermore, n3 and n4 in formula (1) and formula (2) are each independently an integer of 0 to 2, preferably an integer of 0 to 1, and particularly preferably 0. That is, the compound represented by formula (2) is particularly preferably a compound represented by the following formula (2-A).

[0017] [ka]

[0018] In the present invention, the amount (molar ratio) of the compound represented by formula (1) to ethylene carbonate used is 1:1.9 to 1:2.9, preferably 1:2 to 1:2.7, and more preferably 1:2.1 to 1:2.5. If the amount of ethylene carbonate used is less than 1:1.9, the reaction time may be prolonged. Furthermore, the compound represented by formula (1) may remain unreacted, and an increase in the amount of by-products resulting from the reaction of 1 mole of the compound represented by formula (1) with 1 mole of ethylene carbonate undesirably decreases the yield and purity. If the amount of ethylene carbonate used is more than 1:2.9, an increase in the amount of by-products resulting from the reaction of 1 mole of the compound represented by formula (1) with 3 or more moles of ethylene carbonate undesirably decreases the yield and purity.

[0019] In the present invention, it is preferable to have a predetermined amount of nonreactive solvent present during the reaction. The nonreactive solvent is not particularly limited as long as it does not inhibit the reaction, and examples include aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; aliphatic hydrocarbons such as pentane, hexane, and heptane; halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene; halogenated aliphatic hydrocarbons such as dichloromethane and 1,2-dichloroethane; dimethylformamide and dimethyl sulfoxide. Toluene and dimethylformamide are preferred, and dimethylformamide is more preferred. If the predetermined amount of nonreactive solvent is not present, stirring may become difficult, resulting in the reaction not proceeding or being significantly delayed. In this case, to proceed with the reaction, it is necessary to increase the temperature or dilute the reaction system with a large amount of solvent (more than the predetermined amount) to dissolve or create a stirrable slurry in the reaction system. However, high reaction temperatures can increase the amount of by-products such as polymers, resulting in a decrease in yield and purity, or a deterioration in hue due to coloration.

[0020] In the present invention, the amount of non-reactive organic solvent used during the reaction is preferably 0.1 to 10 times by weight, more preferably 0.3 to 7 times by weight, and even more preferably 0.5 to 5 times by weight relative to the compound represented by formula (1). If the amount of solvent used is less than 0.1 times by weight, stirring of the compound represented by formula (1) and the resulting compound represented by formula (2) may be difficult. If the amount of solvent used is more than 10 times by weight, the reaction time may be delayed, volumetric efficiency may decrease, and production efficiency may deteriorate, resulting in economical disadvantages. Furthermore, prolonged heating operations may increase side reaction products and cause coloration. In the present invention, the reaction is preferably carried out using the predetermined amount of ethylene carbonate and the predetermined amount of non-reactive organic solvent. This allows the compound represented by formula (1), which has a high melting point and low solubility in ethylene carbonate and organic solvents, to be most efficiently reacted in a solution or a stirrable slurry state, thereby producing a compound represented by formula (2) in high yield and high purity.

[0021] In the present invention, the method for reacting the compound represented by formula (1) with a predetermined amount of ethylene carbonate is not particularly limited, but the reaction can usually be carried out by charging the compound represented by formula (1), ethylene carbonate, a solvent, and a catalyst into a reaction vessel and heating and stirring them in air or in an inert gas atmosphere such as nitrogen or helium. The reaction can be monitored by an analytical means such as liquid chromatography.

[0022] In the present invention, the reaction temperature is not particularly limited, but is usually 150°C or lower, preferably 140 to 40°C, and more preferably 130 to 70°C. If the reaction temperature is too high, the yield may decrease and the color may deteriorate due to an increase in by-products. If the reaction temperature is too low, the reaction may not proceed quickly.

[0023] The catalyst used in the present invention may be either an alkali catalyst or an acid catalyst, but an alkali catalyst is preferred because it promotes rapid reaction and reduces impurities. Examples of alkali catalysts include potassium hydroxide, sodium hydroxide, barium hydroxide, magnesium oxide, sodium carbonate, and potassium carbonate. Potassium hydroxide, sodium hydroxide, and potassium carbonate are particularly preferred. The use of an acid catalyst is not particularly limited, and examples include sulfuric acid, paratoluenesulfonic acid, and methanesulfonic acid. The amount of catalyst used is not particularly limited, but is typically preferably 0.01 to 0.5 mol, more preferably 0.05 to 0.2 mol, per mol of the compound represented by formula (1). If the amount of catalyst is too small, the reaction may not proceed or may be delayed. If the amount of catalyst is too large, the yield and purity may decrease due to an increase in by-products, and coloration may occur.

[0024] (Process 2) In the present invention, a step (hereinafter referred to as an alkali purification step) is carried out in which an aqueous alkali solution having a concentration of 3% by weight or more is added to a reaction mixture solution containing a compound represented by formula (2) obtained by reacting a compound represented by formula (1) with a predetermined amount of ethylene carbonate, and the mixture is heated and stirred at a temperature of 50°C or higher.

[0025] In the present invention, the concentration of the alkaline aqueous solution added to the reaction mixture solution containing the compound represented by formula (2) is 3% by weight or more, preferably 6% by weight, and more preferably 8% by weight or more. By adding an alkaline aqueous solution with a concentration of 3% by weight or more and heating and stirring at a temperature of 50°C or higher, the by-product formed by the reaction of 1 mole of the compound represented by formula (1) with 3 moles or more of ethylene carbonate decomposes to form the compound represented by formula (2). Furthermore, since coloring components can be removed into the alkaline aqueous solution, a highly pure compound represented by formula (2) with little coloring can be obtained. A concentration of the alkaline aqueous solution lower than 3% by weight is undesirable because it makes it difficult to efficiently remove by-products and coloring components. The alkaline concentration is not particularly limited as long as it is 3% by weight or more. However, considering the solubility of the alkali and ease of handling, a concentration of 50% by weight or less, more preferably 30% by weight or less, and even more preferably 15% by weight or less is preferred.

[0026] The temperature at which the aqueous alkaline solution is heated and stirred is 50°C or higher, preferably 60°C or higher, more preferably 80°C or higher, and is preferably below the boiling point of the solvent used, more preferably 130°C or lower. Temperatures below 50°C are undesirable because by-products cannot be removed or cannot be removed efficiently. Temperatures above 130°C are also undesirable because they increase impurities, reducing purity and worsening color. The stirring time is not particularly limited, but is preferably 0.5 to 10 hours, more preferably 1 to 9 hours, and even more preferably 2 to 8 hours.

[0027] The alkali used in the alkaline aqueous solution of the present invention is not particularly limited, but examples include lithium hydroxide, sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, and potassium carbonate. Sodium hydroxide and potassium hydroxide are preferred. The amount of alkali used is not particularly limited, but to efficiently remove by-products and coloring components, it is usually preferably 0.1 to 20 mol, more preferably 0.2 to 10 mol, and even more preferably 0.3 to 5 mol, per mol of the compound represented by formula (1). If the amount of alkali is less than 0.1 mol, by-products may not be efficiently removed. Furthermore, coloring components may not be efficiently removed, which is undesirable. If the amount of alkali is more than 20 mol, purity may decrease and color may worsen, which is undesirable.

[0028] In the present invention, the alkaline purification step may be performed by adding an alkaline aqueous solution to a reaction mixture solution containing the compound represented by formula (2) and heating and stirring, or by diluting the reaction mixture solution with an organic solvent and then adding an alkaline aqueous solution and heating and stirring. This step is usually performed after dilution with an organic solvent. The organic solvent used for dilution is not particularly limited, but examples include aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; aliphatic hydrocarbons such as pentane, hexane, and heptane; halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene; dimethylformamide; and dimethyl sulfoxide. Toluene and dimethylformamide are preferred, and dimethylformamide is more preferred. After the alkaline purification step, the alkaline aqueous solution can be separated and removed. Furthermore, other purification steps such as water washing, adsorption treatment, and filtration may be added after the alkaline purification step.

[0029] Generally, the compound represented by formula (2) is more difficult to crystallize as the amount of by-products to which 3 moles or more of ethylene carbonate are added increases. However, in the present invention, the amount of these by-products is small, so that crystallization is easy, and crystals of the compound represented by formula (2) having good hue and purity can be obtained.

[0030] In the present invention, the purity of the compound represented by formula (2) may be further increased by crystallization purification or other methods. The organic solvent used for crystallization purification is not particularly limited, but examples include aromatic hydrocarbons such as toluene, xylene, and mesitylene; aliphatic hydrocarbons such as hexane and heptane; halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene; alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate and butyl acetate; dimethylformamide; and dimethyl sulfoxide. These organic solvents can be used alone or in combination of two or more. These solvents can be added fresh, or the solvent used in the alkali purification step can be used as is without any additional addition. The amount of organic solvent used is not particularly limited, but from an economical standpoint, it is usually at least 1 weight-fold, preferably 1 to 50 weight-fold, and more preferably 3 to 20 weight-fold, relative to the compound represented by formula (2).

[0031] Crystallization purification can be carried out by a general method and is not particularly limited. Typically, the mixture to be crystallized is heated to a temperature at which the crystals dissolve, for example, 60°C or higher, preferably 80°C or higher, and then the solution is cooled to an appropriate temperature, for example, -10 to 30°C, to obtain the target crystals. The precipitated crystals can be recovered by filtration or the like, and can be isolated by washing and drying as necessary. The isolated crystals may also be purified as necessary. Examples of purification methods include recrystallization and impurity removal treatment using an adsorbent such as activated carbon.

[0032] <Binaphthalene compounds> In the present invention, the purity of the compound represented by formula (2) is preferably 95% or more, more preferably 97% or more, and even more preferably 99% or more. Regarding the purity in the present invention, % is an area percentage value excluding the solvent in high performance liquid chromatography (HPLC) measurement.

[0033] In the present invention, the solution APHA of the compound represented by formula (2-A) is preferably 100 or less, more preferably 80 or less, and even more preferably 50 or less. If the solution APHA is higher than 100, when the compound is used as an optical resin raw material, it may adversely affect the color of the resin or the optical components using the resin.

[0034] In the present invention, the solution APHA is measured by dissolving 0.5 g of the compound represented by the formula (2-A) in 10 ml of dimethylformamide, and measuring the transmittance of the measurement sample using a colorimeter. [Example]

[0035] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0036] In the examples, various measurements were carried out as follows. (1) High-performance liquid chromatograph (HPLC) measurement Measurement was carried out using a Hitachi high performance liquid chromatograph L-2350 under the measurement conditions shown in Table 1. In the examples, unless otherwise specified, % refers to an area percentage value corrected by excluding the solvent in HPLC.

[0037] [Table 1]

[0038] (2) APHA measurement A solution of 0.5 g of the measurement sample dissolved in 10 ml of dimethylformamide was placed in a φ25 mm test tube and measured using a TZ6000 manufactured by Nippon Denshoku Seikogyo Co., Ltd.

[0039] [Example 1] (Process 1) A flask equipped with a stirrer, condenser, and thermometer was charged with 40.00 g (0.091 mol) of 6,6'-diphenyl-1,1'-bi-2-naphthol (hereinafter sometimes abbreviated as BN-6Ph), 18.47 g (0.210 mol) of ethylene carbonate, 1.31 g of potassium carbonate, and 40 ml of dimethylformamide, and the mixture was reacted at 120 °C for 9 hours. HPLC analysis revealed that the content of BN-6Ph was 0.1%, the content of 2,2'-bis(2-hydroxyethoxy)-6,6'-diphenyl-1,1'-binaphthalene (hereinafter sometimes abbreviated as BN2EO-6Ph) was 95.1%, and the content of by-products resulting from the reaction of 1 mole of BN-6Ph with 3 or more moles of ethylene carbonate was 3.0%.

[0040] (Process 2) The reaction mixture solution obtained in step 1 was diluted with 60 ml of dimethylformamide, followed by addition of 9 ml of 10 wt % aqueous sodium hydroxide solution and stirring at 110°C for 4 hours. The reaction solution was then added dropwise to 2 L of distilled water with stirring to crystallize BN2EO-6Ph. The crystals were collected and subjected to slurry washing three times with 2 L of distilled water. The collected crystals were dried in vacuo at 90°C for 7 hours to obtain 46 g of BN2EO-6Ph crystals (yield: 96%, purity: 99.1%, by-products resulting from the reaction of 3 or more moles of ethylene carbonate per mole of BN-6Ph: 0.0%, APHA: 50).

[0041] [Example 2] (Process 1) A flask equipped with a stirrer, condenser, and thermometer was charged with 35.00 g (0.080 mol) of BN-6Ph, 16.16 g (0.184 mol) of ethylene carbonate, 1.15 g of potassium carbonate, and 35 ml of toluene, and the mixture was reacted at 110°C for 11 hours. HPLC analysis revealed that the BN-6Ph content was 0.1%, BN2EO-6Ph content was 91.5%, and by-products resulting from the reaction of 1 mole of BN-6Ph with 3 or more moles of ethylene carbonate accounted for 4.2%.

[0042] (Process 2) The resulting reaction mixture was diluted with 50 ml of toluene, and then 8 ml of a 10 wt % aqueous sodium hydroxide solution was added and stirred at 110°C for 4 hours. After the reaction was completed, the reaction solution was transferred to a separatory funnel and washed with distilled water until neutral. The reaction solution was concentrated and then recrystallized once with methyl ethyl ketone to obtain 39 g of BN2EO-6Ph crystals (yield: 93%, purity: 98.6%, by-products resulting from the reaction of 3 or more moles of ethylene carbonate per mole of BN-6Ph: 0.0%, APHA: 30).

[0043] [Comparative Example 1] After the reaction according to the method described in Example 1.5 of Patent Document 1 (which involves reacting a compound represented by formula (1) with ethylene carbonate in a molar ratio of 1:3, but does not include the steps of adding 3% by weight or more of an alkaline aqueous solution and heating and stirring at a temperature of 50°C or higher, the method does not satisfy claim 1 of the present invention), HPLC analysis revealed that BN-6Br was 0.1%, BNEO-6Ph was 92.8%, and by-products resulting from the reaction of 3 moles or more of ethylene carbonate per mole of BN-6Ph were 5.3%. Subsequently, washing, purification, and drying were carried out according to the method described in Example 1.5 of Patent Document 1 to obtain BNEO-6Ph (yield: 69%, purity: 99%, by-products resulting from the reaction of 3 moles or more of ethylene carbonate per mole of BN-6Ph: 0.5%, APHA: 150). The yield was low because the process of adding 3% by weight or more of an alkaline aqueous solution and heating and stirring at a temperature of 50°C or higher was not carried out, and by-products were removed by washing and recrystallization. [Industrial Applicability]

[0044] According to the present invention, a binaphthalene compound having high purity and excellent color can be obtained in good yield, and therefore, it is suitable for use as a raw material for optical resins.

Claims

1. A method for producing a compound represented by formula (2) below by reacting a compound represented by formula (1) below with ethylene carbonate, the method comprising the following steps 1 and 2: Step 1: A step of reacting a compound represented by formula (1) with ethylene carbonate in a molar ratio of 1:1.9 to 1:2.9 in the presence of dimethylformamide as a non-reactive solvent in an amount of 0.1 to 10 times by weight relative to the compound represented by formula (1). Step 2: After the reaction in Step 1 is completed, an aqueous alkali solution having a concentration of 3% by weight or more is added to the resulting reaction mixture solution, and the solution is heated and stirred at a temperature of 50°C or higher. 【Chemical 1】 【Chemistry 2】 (In formula (1) and formula (2), X １ ~X ４ are each independently an aromatic group having 4 to 36 carbon atoms which may contain a heteroatom and which may have a substituent, n1 and n2 are each independently an integer of 1 to 4, and n3 and n4 are each independently an integer of 0 to 2.

2. 2. The method for producing the compound according to claim 1, wherein in step 2, the reaction mixture solution is diluted with dimethylformamide, and then an aqueous alkali solution having a concentration of 3% by weight or more is added.

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