JP2003128609A - Purification method of fluorenylidenediphenol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that effectively eliminates oxidized by-products contained in a fluorenylidenediphenol. SOLUTION: The purification method of a fluorenylidenediphenol represented by formula (1) (wherein, R1 , R2 , R3 , and R4 are each independently H, 1-20C alkyl, 6-20C aryl, 1-20C alkyloxy, or 6-20C aryloxy) comprises its recrystallization after dissolving into an organic solvent separated from water phase and bringing into contact with an aqueous solvent containing a reducing agent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for purifying fluorenylidene diphenols which are aromatic dihydroxy compounds. Fluorenylidene diphenols are useful substances as raw materials for polycarbonate resins, polyester resins, epoxy resins and the like. In particular, since the polycarbonate resin has excellent transparency, it has excellent physical properties as an optical material such as an optical disk, an optical fiber, an optical film, a lens, a prism, and a light guide plate, and is industrially useful.

[0002]

Fluorenylidene diphenols are synthesized from fluorenone and phenols using an acid as a catalyst. The crude product is colored yellow. Therefore, commercially available products are usually white crystals purified using a ketone-based, alcohol-based, hydrocarbon-based, or water-based solvent.

As a specific purification method, for example, US Pat. No. 4,049,721 discloses a method of recrystallizing 9,9-bis (4-hydroxyphenyl) fluorene in a methanol-water mixed solvent. In addition, JP-A-4-4
In Japanese Patent No. 1451, fluorenylidene diphenols are dissolved in an aliphatic ketone, an insoluble substance is filtered off, the aliphatic ketone is distilled off, and recrystallized again with a mixed solvent of an aliphatic alcohol and an aromatic hydrocarbon. It shows how to do it. Further, in Japanese Patent Application Laid-Open No. 6-321836, 9,
A method is disclosed in which 9-bis (4-hydroxyphenyl) fluorene is dissolved in acetic acid ester and then an aliphatic hydrocarbon solvent is added to precipitate crystals. Further, in JP-A-10-245352, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene has 1 carbon atom.
Methods of recrystallizing with a mixed solvent of an aliphatic alcohol having 3 to 3 and an aliphatic ketone having 3 to 7 carbon atoms and the like are shown.

However, none of the methods has been able to obtain sufficiently high-purity fluorenylidene diphenols. In particular, when it is used as a raw material when synthesizing a polycarbonate resin by the melt polycondensation method, there is a problem that the product is colored. When synthesizing a polycarbonate resin by the melt polycondensation method, unlike the interfacial polymerization method in the manufacturing process of the polycarbonate resin, there is no step of separating the polycarbonate resin, so that it is present in a slight amount in the raw material fluorenylidene diphenols. Even if impurities are exposed to high temperatures for a long period of time to cause undesired side reactions to cause coloration of the resin, it is difficult to remove the by-products, so that particularly high-purity fluorenylidene diphenols are required as raw materials.

When the polycarbonate resin is used for optical materials, it is not preferable that it is colored in view of its appearance or the light transmittance of a laser beam having a specific wavelength. Particularly in the field of spectacle lenses, it is strongly required to be colorless, and in the fields of pickup lenses and optical discs to have a high light transmittance at a specific wavelength. Therefore, in producing a polycarbonate resin using fluorenylidene diphenols as a raw material, a method for purifying fluorenylidene diphenols with high purity is required so that a colorless resin can be obtained.

[0006]

The present inventors have investigated and found that 9,9-bis (4-hydroxyphenyl) fluorene and 9,9-bis (one of fluorenylidene diphenols In 4-hydroxy-3-methylphenyl) fluorene, an oxidizable by-product, which is believed to have been oxidized to a carbonyl ring structure or a quinone-like structure, was found. A compound containing a carbonyl group causes various side reactions in the presence of a basic catalyst to color the polycarbonate resin. However, it is difficult to remove these oxidized byproducts by recrystallization.

Therefore, it is an object of the present invention to effectively remove oxidative by-products contained in fluorenylidene diphenols by reducing them, followed by recrystallization.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that an organic solvent that separates fluorenylidene diphenols represented by the following general formula (1) from water into layers. It was found that the fluorenylidene diphenols can be purified by dissolving them in water, contacting them with an aqueous solution containing a reducing agent, and then performing recrystallization.

[Chemical 2] (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a carbon number 6
To an aryl group having 20 to 20 carbon atoms, an alkyloxy group having 1 to 20 carbon atoms, or an aryloxy group having 6 to 20 carbon atoms)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The fluorenylidene diphenols used in the present invention may be of high purity or low purity, but the effect of contact with a reducing agent is maximized. Therefore, it is desirable to use fluorenylidene diphenols having the highest possible purity. When using a low-purity fluorenylidene diphenol, it is appropriate to perform an operation such as recrystallization in advance to increase the purity. The purity of the preferred fluorenylidene diphenols is 95% or more, more preferably 98% or more.

The fluorenylidene diphenols used in the present invention may be obtained by any production method. Basically, if phenols and fluorenone are reacted in the presence of an acid catalyst,
All can be applied regardless of the catalyst or reaction conditions.

Examples of the organic solvent capable of dissolving fluorenylidene diphenols and capable of phase-separating from water include alcohols having a large number of carbon atoms, esters, ethers and aromatic hydrocarbons. Alcohols having properties are preferably used. Specifically, 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1.
-Butanol, 3-methyl-2-butanol, 1-hexanol, 1-heptanol, 1-octanol, 2-
Examples thereof include ethylhexanol, 1-nonanol, 1-decanol, cyclopentanol, cyclohexanol, etc., but since they are inexpensive and have high solubility of fluorenylidene diphenols, 1-butanol, 1-pentanol or 1-Hexanol is preferably used. When the fluorenylidene diphenols contain impurities that are insoluble in the solvent, such as multimers or solid foreign substances, they are preferably removed by filtration.

The reducing agent is not particularly limited as long as it is stable in an aqueous solution state, and examples thereof include a sulfur-based reducing agent and a boron-based reducing agent. Specific examples include sodium hydrogen sulfite, sodium sulfite, sodium thiosulfate, sodium hydrosulfite, sodium borohydride and the like. Among them, the sulfur-based reducing agent is inexpensive and has a strong reducing power, and is preferably used, and sodium bisulfite is particularly preferably used.

The reducing agent aqueous solution exhibits a greater effect of reducing by-products to be oxidized by adding acid or alkali to adjust the pH. The pH of the reducing agent aqueous solution is preferably 3 to 13, and more preferably 5 to 9. pH
Examples of acids or alkalis that adjust the pH include hydrochloric acid, sodium hydroxide, potassium hydroxide, lithium hydroxide,
Sodium carbonate, potassium carbonate, sodium hydrogen carbonate,
Ammonia water is exemplified.

The concentration of the fluorenylidene diphenol solution is not particularly limited, but it is preferably 1 to 25 wt%, more preferably 10 to 20 wt%. 1 wt%
If it is lower than 25% by weight, the operation efficiency becomes poor. If it is higher than 25% by weight, crystals are likely to precipitate during the contact, which is not preferable.

The concentration of the reducing agent aqueous solution is not particularly limited, but is preferably 0.001 mol / l to 5 mol /
1 and more preferably 0.01 to 2 mol / l. If the concentration is less than 0.001 mol / l, the reduction effect is weakened, and if it exceeds 5 mol / l, a large amount of pure water is required for subsequent washing of the organic layer with pure water, which is not preferable because the operation becomes complicated.

The volume ratio of the fluorenylidene diphenol solution to be contacted and the aqueous solution containing the reducing agent is preferably 0.1: 10 to 10: 0.1 from the viewpoint of stirring efficiency, and more preferably It is preferably 1: 5 to 5: 1.

The temperature at which the fluorenylidene diphenol solution and the aqueous solution containing the reducing agent are brought into contact with each other is not particularly limited as long as the reducing agent can effectively exert its reducing power, but 5 to 95 ° C. Preferably, more preferably 1
It is 5-80 degreeC. The contacting method is sufficient if the two layers are sufficiently suspended, and may be vigorously stirred by rotating a shaft having a stirring blade such as a paddle blade, stirring with a stirring bar, or a separating funnel. You may put it in a container of the type and shake it.

The reducing operation may be carried out under air, but it is more preferable to carry out under an inert gas atmosphere because the reducing agent is oxidized by oxygen. Specific examples include a nitrogen atmosphere, an argon atmosphere, a carbon dioxide atmosphere, and the like. Above all, a nitrogen atmosphere using inexpensive nitrogen gas is preferable.

After contacting the fluorenylidene diphenol solution with an aqueous solution containing a reducing agent, the fluorenylidene diphenol solution layer is washed with pure water. The temperature of pure water used for washing with water is not limited, but is preferably the same temperature as that of the organic solvent layer. The amount of pure water used per washing with water and the number of washings are not particularly limited. The dissolved reducing agent may be removed from the fluorenylidene diphenol solution layer. The amount of pure water used per washing is 0.1 to 1 by volume ratio with respect to the fluorenylidene diphenol solution layer.
0, and the number of washings is preferably 1 to 5 times.

In the present invention, the fluorenylidene diphenol solution is brought into contact with an aqueous solution containing a reducing agent, and the fluorenylidene diphenol solution layer is washed with pure water.
Highly pure fluorenylidene diphenol can be obtained by recrystallizing the fluorenylidene diphenol, which is preferably carried out. Recrystallization may be carried out by distilling off all the solvent, recovering fluorenylidene diphenol, and dissolving again in the recrystallization solvent by heating, cooling and crystallization, or if the temperature after washing with pure water is sufficiently high, It may be cooled as it is for crystallization, or a poor solvent may be added to the fluorenylidene diphenol solution layer for crystallization.

When all the organic solvent used for washing is distilled off and fluorenylidene diphenol is recrystallized again, fluorenylidene diphenol is sufficiently dissolved near the boiling point of the recrystallization solvent and cooled. A known recrystallization method for crystallization is used. As the recrystallization solvent, monoalcohol having 3 or less carbon atoms is preferably used. In particular,
They are methanol, ethanol, 1-propanol and 2-propanol. Further, an alcohol-pure water mixed solvent obtained by adding pure water to these monoalcohols or an alcohol-hydrocarbon mixed solvent obtained by adding hydrocarbons can also be used as the recrystallization solvent. In this case, the weight fraction of alcohol and water is preferably alcohol / pure water = 1/3 or more, and more preferably 1/1 to 10/1. The weight fraction of alcohol and hydrocarbon is preferably alcohol / hydrocarbon = 1/5 or more, and more preferably 1 / 2-10 / 1. Specific hydrocarbons that can be used include benzene, toluene, xylene, ethylbenzene, mesitylene, pseudocumene, hexane,
Heptane, octane, cyclohexane, etc. are illustrated.

When a poor solvent is added to the fluorenylidene diphenol solution layer for crystallization, a hydrocarbon solvent is preferably used as the poor solvent. Specifically, benzene,
Examples include toluene, xylene, ethylbenzene, mesitylene, pseudocumene, hexane, heptane, octane and cyclohexane. The temperature of the fluorenylidene diphenol solution layer at the time of adding the poor solvent is not particularly limited, but is usually not higher than the boiling point of the solvent used for the solution layer. The poor solvent may be added after heating, but it is preferable that the temperature is not higher than the boiling point of the solvent used in the solution layer.

When the fluorenylidene diphenol is dissolved by heating and then crystallized, the cooling rate is not particularly limited, but in order to prevent the incorporation of impurities, it is cooled at a slow rate of 10 ° C./minute or less. Is preferred. Also,
During crystallization, it is preferable to carry out crystallization while slowly stirring so that the crystals do not adhere to each other.

The crystallized crystals are recovered by a known crystal recovery means. Specifically, means such as filtration and centrifugation are preferably used. Since the obtained crystals contain a small amount of mother liquor, the crystals are washed to such an extent that the recrystallization yield does not decrease too much. The crystal washing solvent is preferably a solvent having the same composition as the recrystallization solvent.

[0025]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The 9,9-bis (4-hydroxy-3) used in the examples
-Methylphenyl) fluorene is a commercially available product with white microcrystalline properties.

The physical properties of the polycarbonate resin were measured by the following methods. 1) Polystyrene-converted weight average molecular weight (Mw) Using GPC, using chloroform as a developing solvent, a calibration curve was prepared using polystyrene having a narrow molecular weight distribution (Mw / Mn = about 1) and a known molecular weight, and based on this calibration curve. Measured. 2) Yellow index (YI) A pressed test piece having a diameter of 42 mm and a thickness of 3 mm was molded and measured with a color difference meter.

Example 1 9,9-bis (4-hydroxy-3-methylphenyl)
200 g of fluorene (purity: 99.5%) was placed in a 3 L four-necked flask equipped with a stirrer and a thermometer and equipped with a withdrawal cock at the bottom, and stirred and dissolved in 1200 g of 1-butanol at 25 ° C. The solution was pale yellow.
1 mol / L sodium hydrogen sulfite aqueous solution (p
H = 5) (1000 g) was added, and the mixture was suspended in a nitrogen atmosphere with vigorous stirring and stirred at 25 ° C. for 18 hours.
Next, sodium carbonate was added so that pH = 6, and the mixture was further stirred at 25 ° C. for 2 hours and suspended. afterwards,
When left to stand, the organic layer became colorless. The aqueous layer was removed, leaving only the organic layer, and 1000 g of pure water was charged into the flask and vigorously stirred to wash the organic layer. The washing operation was performed three times, and it was confirmed that the pH of the third washing drainage was pH = 7. The organic layer was taken out and 1-butanol was distilled off under reduced pressure to obtain 200 g of a white solid. 200 g of this white solid
Is dissolved in a mixed solvent of 867 g of methanol and 333 g of pure water by heating at 64 ° C., and 12
It was left for a time, cooled to 23 ° C., and crystallized. The crystals were separated by filtration, washed 3 times with a mixed solution of 52 g of methanol and 20 g of pure water, 3 times with 50 g of water, and dried under vacuum at 90 ° C. for 12 hours. The obtained crystals were white and the yield was 169 g.

9,9-Bi purified by the above method
Sus (4-hydroxy-3-methylphenyl) fluorene
37.8 g (0.1 mol), tricyclo [5.2.
1.0 ^2,6] Decanedimethanol 19.6 g (0.1 m
ol), 43.7 g of diphenyl carbonate (0.2 m
ol), and sodium bicarbonate 6 × 10^-7g (5 x
10^-Fivemol) 300m with stirrer and distillation device
1 Place in a four-necked flask and in a nitrogen atmosphere at atmospheric pressure for 1
Heat to 80 ° C. and stir for 20 minutes. After that,
Adjust to 150mmHg and at the same time 60 ℃ / hr speed
To 200 ° C and hold at 200 ° C for 40 minutes
A transesterification reaction was performed. Furthermore, the speed of 75 ° C / hr
Temperature to 225 ° C and hold at 225 ° C for 20 minutes.
A stell exchange reaction was performed. Then keep at 225 ° C
The degree of pressure reduction was 1 mmHg over 1 hour. afterwards,
The temperature was raised to 240 ° C. at a rate of 90 ° C./hr. further,
Reaction is carried out for 50 minutes under the conditions of 240 ° C and 1 mmHg.
It was After completion of the reaction, blow nitrogen into the reactor to return it to normal pressure.
Then, the produced polycarbonate resin was taken out. Generate
The polycarbonate resin made has Mw = 57700, YI =
It was 2.39.

Example 2 Example 1 was repeated except that 1 mol / l sodium bisulfite aqueous solution (pH = 7) was used in place of 1 mol / l sodium hydrogen sulfite aqueous solution, and sodium carbonate was not added. The same operation was performed. The yield of crystals was 169 g. Further, a polycarbonate was produced by a transesterification reaction in the same manner as in Example 1. The polycarbonate resin thus produced had Mw = 55600 and YI = 2.
It was 57.

Example 3 Same as Example 1 except that 1 mol / l sodium hydrogen sulfite aqueous solution (pH = 9) was used in place of 1 mol / l sodium hydrogen sulfite aqueous solution, and sodium carbonate was not added. The operation was performed. The crystal yield was 171 g. Further, a polycarbonate was produced by a transesterification reaction in the same manner as in Example 1. The produced polycarbonate resin has Mw = 56800, YI = 2.6.
It was 6.

Example 4 Example 1 was repeated except that 1 mol / l sodium hydrosulfite aqueous solution (pH = 6) was used in place of 1 mol / l sodium hydrogen sulfite aqueous solution and sodium carbonate was not added. The same operation was performed. The crystal yield was 171 g. Further, a polycarbonate was produced by a transesterification reaction in the same manner as in Example 1. The polycarbonate resin produced has Mw = 5620.
0 and YI = 2.50.

Example 5 The same operation as in Example 1 was carried out except that 1-hexanol was used in place of 1-butanol in Example 1. The yield of crystals was 174 g. Further, a polycarbonate was produced by a transesterification reaction in the same manner as in Example 1. The polycarbonate resin produced has Mw = 5440
0 and YI = 2.41.

Example 6 In Example 1, 9,9-bis (4-hydroxy-3)
The same operation as in Example 1 was carried out, except that the amount of -methylphenyl) fluorene charged was 150 g and that 2-ethylhexanol was used instead of 1-butanol. The crystal yield was 127 g. Further, a polycarbonate was produced by a transesterification reaction in the same manner as in Example 1. The polycarbonate resin produced has Mw = 5590
0 and YI = 2.39.

Comparative Example 1 In Example 1, 9,9-bis (4-hydroxy-3)
Polymerization was performed in the same manner as in Example 1 without performing any purification operation of -methylphenyl) fluorene. Also,
Polycarbonate was produced by the transesterification reaction in the same manner as in Example 1. The polycarbonate resin produced is Mw
= 55500 and YI = 4.52.

Comparative Example 2 In Example 1, 9,9-bis (4-hydroxy-3)
-Methylphenyl) fluorene was subjected to the same operation as in Example 1 without performing a refining operation with a reducing agent aqueous solution.
A recrystallization operation from pure water was performed. Further, a polycarbonate was produced by a transesterification reaction in the same manner as in Example 1. The polycarbonate resin produced has Mw = 5690
0, YI = 3.75.

[0036]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to highly purify fluorenylidene diphenols in high yield by bringing them into contact with a reducing agent. Therefore, it is possible to obtain a polycarbonate resin having an excellent color tone, which contains fluorenylidene diphenols as a monomer, and the polycarbonate resin can be used as an optical material for optical discs, optical fibers, optical films, lenses, prisms, light guide plates and the like, It is useful.

Claims (6)

[Claims] 1. Recrystallization is carried out after dissolving a fluorenylidene diphenol represented by the following general formula (1) in an organic solvent that separates from water and contacting it with an aqueous solution containing a reducing agent. A method for purifying fluorenylidene diphenols, which comprises: [Chemical 1] (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a carbon number 6
Represents an aryl group having 20 to 20 carbon atoms, an alkyloxy group having 1 to 20 carbon atoms, or an aryloxy group having 6 to 20 carbon atoms. ) 2. The method for purifying fluorenylidene diphenols according to claim 1, wherein the reducing agent is a sulfur-based reducing agent. 3. The pH of an aqueous solution containing a reducing agent is 3 to 1.
3. The method for purifying fluorenylidene diphenols according to claim 1, which is 3. 4. The organic solvent which is phase-separated from water has 4 to 1 carbon atoms.
The method for purifying fluorenylidene diphenols according to claim 1, wherein the monohydric alcohol is 0. 5. The method for purifying fluorenylidene diphenols according to claim 1, wherein the reducing agent is sodium hydrogen sulfite. 6. Fluorenylidene diphenol is 9,9
The method according to claim 1, which is -bis (4-hydroxy-3-methylphenyl) fluorene.