Method for producing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene

Abstract

To provide a method for producing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene that is more suitable for industrial-scale execution.SOLUTION: It was found that the problem can be solved by precipitating crystals of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene from a solution of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene and a solvent comprising an aromatic hydrocarbon and methanol at a specific ratio and, thereby, 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene can be produced efficiently on an industrial scale.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an improved method for producing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, which is suitable as a monomer for forming resins (optical resins) constituting optical members such as optical lenses and optical films. [Background technology]

[0002] Resin materials such as polycarbonate, polyester, polyacrylate, polyurethane, and epoxy, which are made from 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 and sheets due to their excellent optical properties and heat resistance.

[0003] A known method for obtaining 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene is to react 1,1'-bi-2-naphthol with an alkylene oxide, a halogenoalkanol, or an alkylene carbonate. For example, Japanese Patent Laid-Open Publication No. 2011-153248 (Patent Document 1) discloses, as Synthesis Example 1, a method in which 1,1'-bi-2-naphthol is reacted with an excess amount of ethylene carbonate in the presence of potassium hydroxide as a catalyst, the resulting reaction mixture is dissolved in methyl isobutyl ketone, washed with water, and then the solvent is removed at 150°C to obtain 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene as a resinous substance. Japanese Patent Laid-Open Publication No. 2010-18753 (Patent Document 2) discloses, as Example 1, a method in which 1,1'-bi-2-naphthol and an excess amount of ethylene carbonate are reacted in a toluene solvent in the presence of a potassium carbonate catalyst, the reaction mixture is washed with a 1% aqueous sodium hydroxide solution and water, and then the solvent is removed under reduced pressure using a rotary evaporator to obtain 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene. However, in these methods, the target product is obtained as a resinous concentrated residue by distilling off the solvent from the reaction mixture, and it is difficult to extract it.

[0004] Another method for obtaining crystalline 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene by crystallization is, for example, according to the methods described in Patent Documents 1 and 2, in which 1,1'-bi-2-naphthol and ethylene carbonate are reacted in the presence of an alkali catalyst to obtain a reaction mixture containing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, and the resulting reaction mixture is dissolved in a solvent and then cooled. However, this method is known to instantaneously precipitate a large amount of crystals, making stirring and transport difficult. The present applicant has discovered a solution to this problem in Japanese Patent Laid-Open No. 2015-168658 (Patent Document 3). This method solves the above problem by reusing part or all of the mother liquor obtained in the crystallization procedure of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene to perform crystallization. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-153248 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-18753 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-168658 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method described in Patent Document 3 requires the preparation of a mother liquor in advance through operations such as crystallization and filtration. Therefore, there has been a demand for a method for producing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene that does not require the preparation of a mother liquor.

[0007] An object of the present invention is to provide a method for producing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene which is more suitable for implementation on an industrial scale. [Means for solving the problem]

[0008] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by precipitating crystals of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene (i.e., performing crystallization) from a solution of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene and a solvent containing an aromatic hydrocarbon and methanol in a specific ratio, and that 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene can be efficiently produced on an industrial scale. Specifically, the present invention includes the following inventions.

[0009] [1] A 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene solution containing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, aromatic hydrocarbons, and methanol, wherein the ratio of the aromatic hydrocarbons to the methanol is aromatic hydrocarbons:methanol=99:1 to 10:90 by weight.

[0010] [2] The solution according to [1], wherein the total amount of the aromatic hydrocarbons and methanol is 100 to 2000 parts by weight per 100 parts by weight of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene.

[0011] [3] A method for producing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, comprising a step of crystallizing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene from the solution according to [1] or [2]. [Effects of the Invention]

[0012] According to the present invention, it is possible to advantageously obtain crystals of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene even on an industrial scale without the problems of stirring, transportation, etc. that arise during crystallization in conventional methods and without the need to prepare a mother liquor in advance.

[0013] Furthermore, since the present invention does not require a mother liquor, the influence of impurities contained in the mother liquor can be avoided. Therefore, for example, when it is desired to further improve the purity of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene obtained by the method of Patent Document 3, the purity of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene obtained by the method of Patent Document 3 can be easily and efficiently improved by applying the production method of the present invention (by carrying out so-called recrystallization by the production method of the present invention). DETAILED DESCRIPTION OF THE INVENTION

[0014] <Solution of the Present Invention (2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene Solution)> The solution of the present invention contains 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, an aromatic hydrocarbon, and methanol in specific proportions, and the 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene contained in the solution is preferably completely dissolved.

[0015] The 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene used in the present invention can be obtained, for example, by a conventionally known method (for example, the methods described in Patent Documents 1 to 3 above), and is preferably prepared by reacting 1,1'-bi-2-naphthol with ethylene carbonate, since this makes it easier to achieve the effects of the present invention.

[0016] Examples of aromatic hydrocarbons used in the solution of the present invention include benzene, toluene, xylene, and mesitylene. Among these aromatic hydrocarbons, toluene or xylene is preferred. These aromatic hydrocarbons may be used alone or in combination of two or more. When crystallizing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, using only an aromatic hydrocarbon impedes stirring during crystallization, as described in Patent Document 3 and in the Examples section below. Therefore, methanol must be used in combination. Furthermore, when other alcohols are used instead of methanol, stirring during crystallization becomes difficult, as in the case of using only an aromatic hydrocarbon, as shown in the Examples section below.

[0017] In the solution of the present invention, the ratio of aromatic hydrocarbon to methanol, by weight, is aromatic hydrocarbon:methanol=99:1 to 10:90, preferably 96:4 to 20:80. When the ratio is in the range of aromatic hydrocarbon:methanol=99:1 to 10:90, it is possible to precipitate crystals of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene without making stirring difficult in the production step described below.

[0018] The solution of the present invention may contain other organic solvents in addition to aromatic hydrocarbons and methanol. Examples of the other organic solvents that may be contained include aliphatic hydrocarbons, esters, ethers, and ketones. Examples of the aliphatic hydrocarbons include hexane, cyclohexane, and heptane. Examples of the esters include ethyl acetate, isopropyl acetate, and isobutyl acetate. Examples of the ethers include tetrahydrofuran and dioxane. Examples of the ketones include acetone, 2-butanone, 4-methyl-2-pentanone, and cyclohexanone. When other organic solvents are contained, the amount thereof is, for example, 50 parts by weight or less, preferably 30 parts by weight or less, based on 100 parts by weight of the total amount of aromatic hydrocarbons and methanol in the solution.

[0019] In addition, in the solution of the present invention, the total amount of aromatic hydrocarbons and methanol is, for example, 100 to 2000 parts by weight, preferably 150 to 1500 parts by weight, and more preferably 150 to 1000 parts by weight, per 100 parts by weight of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene.

[0020] In the solution of the present invention, 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene is preferably completely dissolved. The temperature at which complete dissolution occurs is usually 40°C or higher and the boiling point of the solvent or lower, preferably 50 to 65°C.

[0021] <Method of producing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene> By precipitating crystals of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene from the solution of the present invention described above by a method such as cooling the solution, it becomes possible to produce crystals of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene without difficulty in stirring during crystallization. The method for producing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene will be described in detail below.

[0022] Crystals of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene can be precipitated by cooling the solution of the present invention to 15°C or lower from the temperature of the solution of the present invention described above, specifically, usually to 25 to 45°C, preferably 30 to 40°C. Cooling is usually performed by standing or slow cooling. Alternatively, crystals can be precipitated by adding seed crystals at a predetermined temperature, if necessary. After crystal precipitation, the solution may be maintained at the same temperature for a certain period of time to allow the crystals to grow, or further cooling may be performed, if necessary.

[0023] The crystallization solution containing the crystals of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene prepared in this way is then subjected to a solid-liquid separation operation to recover the crystals. Examples of the solid-liquid separation operation include filtration operations using a centrifuge, a filter press, a Nutsche, etc., but industrially, a centrifuge is preferred. Thereafter, the recovered crystals may be washed with a solvent or the like or dried as necessary. Further purification such as adsorption and recrystallization may also be performed as necessary.

Example

[0024] Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited thereto. Various measurements were carried out by the following methods. In the following examples and the like, unless otherwise specified, the yield is the actual yield of (RS)-2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene with respect to (RS)-1,1'-bi-2-naphthol used in the reaction, and the HPLC purity is the HPLC area percentage value measured under the following conditions.

[0025] <HPLC measurement conditions> Apparatus: Shimadzu LC-2010A Column: SUMIPAX ODS A-211 (5 μm, 4.6 mmφ × 250 mm) Mobile phase: Water containing 0.03% trifluoroacetic acid / Acetonitrile containing 0.03% trifluoroacetic acid (30% → 100% of acetonitrile containing 0.03% trifluoroacetic acid) Flow rate: 1.0 ml / min, column temperature: 40 °C, detection wavelength: UV 254 nm

[0026] <Example 1> Into a glass reactor equipped with a stirrer, a cooler, and a thermometer, 50 g (0.175 mol) of (RS)-1,1'-bi-2-naphthol, 35 g (0.401 mol) of ethylene carbonate, 2.5 g of potassium carbonate, and 50 g of toluene were charged and stirred at 110 °C for 8 hours to obtain a reaction mixture containing (RS)-2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene. The resulting reaction mixture was diluted with 180 g of toluene, and the organic solvent layer containing the reaction mixture was stirred and maintained at 85°C, and washed with aqueous sodium hydroxide. This organic solvent layer was then washed with water until the wash water became neutral, and the resulting organic solvent layer was dehydrated under reflux. The organic solvent layer was then cooled to 60°C, and 21 g of methanol was added to obtain a crystallized solution. This crystallized solution was cooled to 39°C, held at the same temperature for 1 hour to precipitate crystals, and further cooled to 2°C to obtain a crystallized mixture. The resulting crystallized mixture was stirrable. The precipitated crystals were filtered off, washed twice with 35 g of toluene, and then dried at 80°C under reduced pressure to obtain 53 g of white crystals of (RS)-2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene (yield: 81%, HPLC purity: 99%).

[0027] <Example 2> The same process as in Example 1 was carried out up to dehydration under reflux, except that the amount of toluene added to the reaction mixture was 246 g. The organic solvent layer was then cooled to 60°C, and 12 g of methanol was added to obtain a crystallized solution. This crystallized solution was cooled to 45°C, held at the same temperature for 1 hour to precipitate crystals, and further cooled to 2°C to obtain a crystallized mixture. The obtained crystallized mixture was stirrable. The precipitated crystals were filtered off, washed twice with 35 g of toluene, and then dried at 80°C under reduced pressure to obtain 53 g of white crystals of (RS)-2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene (yield: 81%, HPLC purity: 99%).

[0028] Example 3 The same procedure as in Example 1 was repeated up to dehydration under reflux, except that the amount of toluene added to the reaction mixture was 16 g. The organic solvent layer was then cooled to 62°C, and 263 g of methanol was added to obtain a crystallized solution. This crystallized solution was cooled to 31°C, held at the same temperature for 1 hour to precipitate crystals, and further cooled to 2°C to obtain a crystallized mixture. The obtained crystallized mixture was stirrable. The precipitated crystals were filtered off, washed twice with 35 g of toluene, and then dried at 80°C under reduced pressure to obtain 52 g of white crystals of (RS)-2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene (yield: 79%, HPLC purity: 99%).

[0029] Example 4 The same procedure as in Example 1 was repeated up to dehydration under reflux, except that the amount of toluene added to the reaction mixture was 16 g. The organic solvent layer was then cooled to 64°C, and 33 g of methanol was added to obtain a crystallized solution. This crystallized solution was cooled to 39°C, held at the same temperature for 1 hour to precipitate crystals, and further cooled to 2°C to obtain a crystallized mixture. The obtained crystallized mixture was stirrable. The precipitated crystals were filtered off, washed twice with 35 g of toluene, and then dried at 80°C under reduced pressure to obtain 56 g of white crystals of (RS)-2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene (yield: 85%, HPLC purity: 99%).

[0030] <Example 5> The same process as in Example 1 was carried out up to dehydration under reflux, except that the amount of toluene added to the reaction mixture was 896 g. The organic solvent layer was then cooled to 60°C, and 39 g of methanol was added to obtain a crystallization solution. This crystallization solution was cooled to 30°C, held at the same temperature for 1 hour to precipitate crystals, and further cooled to 2°C to obtain a crystallization mixture. The obtained crystallization mixture was stirrable. The precipitated crystals were filtered off, washed twice with 35 g of toluene, and then dried at 80°C under reduced pressure to obtain 37 g of white crystals of (RS)-2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene (yield: 57%, HPLC purity: 99%).

[0031] <Comparative Example 1> The same operations as in Example 1 were carried out up to the dehydration step under reflux, except that the amount of toluene added to the reaction mixture in Example 1 was changed to 1264 g. When the organic solvent layer was cooled to 30°C, crystals precipitated all at once, making stirring difficult.

[0032] <Comparative Example 2> After carrying out the same operations as in Example 1 up to the water washing step, the resulting organic solvent layer was concentrated to distill off water and toluene. 217 g of methanol was added to the resulting residue, and the temperature was raised to 62°C to completely dissolve the crystals. The resulting solution was then cooled to 35°C, at which point crystals precipitated out all at once, making stirring difficult.

[0033] <Comparative Example 3> After the same operations as in Example 1 were carried out up to the dehydration step under reflux, the organic solvent layer was cooled to 62°C, and 21 g of ethanol was added to obtain a crystallized solution. When this crystallized solution was cooled to 45°C, crystals precipitated all at once, making stirring difficult.

[0034] <Comparative Example 4> After the same operations as in Example 1 were carried out up to the dehydration step under reflux, the organic solvent layer was cooled to 66°C, and 21 g of 2-propanol was added to obtain a crystallized solution. When this crystallized solution was cooled to 55°C, crystals precipitated all at once, making stirring difficult.

[0035] <Comparative Example 5> After performing the same operations as in Example 1 up to the dehydration step under reflux, the organic solvent layer was cooled to 82°C, and 21 g of 1-butanol was added to obtain a crystallized solution. When this crystallized solution was cooled to 53°C, crystals precipitated all at once, making stirring difficult.

Claims

1. A 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene solution comprising 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, aromatic hydrocarbons, and methanol, wherein the ratio of the aromatic hydrocarbons to the methanol is, on a weight basis, aromatic hydrocarbons:methanol=99:1 to 10:90, and the aromatic hydrocarbons are toluene and / or xylene.

2. 2. The solution according to claim 1, wherein the total amount of the aromatic hydrocarbon and methanol is 100 to 2000 parts by weight per 100 parts by weight of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene.

3. A method for producing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, comprising a step of crystallizing 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene from the solution according to claim 1 or 2.