JPS631929B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for purifying crude P·P'-biphenols (hereinafter simply referred to as biphenols) containing various metal compounds or sulfur oxides as impurities. Biphenol has recently attracted attention as a starting material for engineering plastics, and as it is a resin with particularly excellent heat resistance, its development is progressing in various fields. However, a technique for obtaining a purified product of biphenol with a high enough purity to fully utilize the physical properties of the polymer has not yet been developed. Since biphenol is generally a high melting point and high boiling point substance, it is impossible to purify it by distillation. Purification by recrystallization is naturally expected, but since biphenol is relatively insoluble in solvents, it is difficult to select a solvent. Moreover, it is difficult to obtain a purified product of polymeric grade by the usual recrystallization method in which biphenol is simply dissolved in a large amount of solvent and cooled to take out the crystals. Although a method of repeatedly carrying out recrystallization using a large amount of solvent may be effective to some extent, such a method requires large equipment and a great deal of labor, and is not an economical purification method. On the other hand, several methods have been proposed so far for producing biphenol. For example, after biphenyl is sulfonated, it is neutralized to form biphenyl disulfonic acid sodium salt,
Next, a method of reacting under alkaline fusion to form a sodium salt of biphenol and neutralizing it to form biphenol (hereinafter abbreviated as method A),
A method in which tetratert-butyl diphenol is produced by reaction with 2,6-ditertiary butylphenol, and finally dealkylated to produce biphenol in the presence of an aluminum alkoxide catalyst (hereinafter abbreviated as method B), dihalogen A method for obtaining biphenol by treating biphenyl with an alkali to obtain a sodium salt of biphenol and neutralizing this (hereinafter abbreviated as method C), a method for obtaining biphenol by Friedel-Crafts reaction of parachlorophenol and phenol ( (hereinafter abbreviated as method D), etc. Diphenols obtained from these various manufacturing methods contain one or more of alkali metal compounds, alkaline earth metal compounds, aluminum group compounds, or sulfur oxides as impurities, and these impurities It has become clear that it is extremely difficult to separate and remove it using normal recrystallization methods. The present inventors have conducted intensive studies on a method to remove these impurities contained in biphenol and obtain purified biphenol of polymerization grade.
It has been found that the following organic solvents, especially ketones, alcohols, or ethers, dissolve diphenol relatively well, and furthermore, by using these solvents, it is possible to dissolve diphenols that are difficult to dissolve, such as alkali metal compounds, alkaline earth metal compounds, aluminum group compounds, or Most impurities such as sulfur oxides are precipitated and separated from the biphenol solution, and the solution containing these precipitates and in which biphenol is dissolved is treated with activated carbon, and then the solution is brought into contact with an ion exchange resin to purify the polymer grade. It was discovered that biphenol can be obtained. That is, the present invention is based on the general formula [In the formula, R represents hydrogen or an alkyl group. ] The boiling point of crude P・P'-biphenols expressed as
This is a method for purifying crude P·P'-biphenol, which consists of dissolving it in an organic solvent at 100°C or lower, treating the resulting solution with an ion exchange resin, and then crystallizing it. The raw material crude biphenol used in the present invention is not particularly limited, but includes, for example, alkali metal compounds obtained by the above-mentioned methods A to D, etc.
It is a crude biphenol containing impurities such as alkaline earth metal compounds, aluminum group compounds, or sulfur oxides. The alkali metal compounds, alkaline earth metal compounds, or aluminum group compounds shown here are, for example, hydroxides, oxides, inorganic acid salts, and organic acid salts of these metals, and the sulfur oxides are:
Sulfuric acid, sulfonic acid or salts thereof. The organic solvent used in the present invention has a boiling point of 100°C.
It has the following and sufficiently dissolves biphenol, and impurities such as alkali metal compounds, alkaline earth metal compounds, aluminum group compounds or sulfur oxides are difficult to dissolve in the solvent, and when crystallizing, It is necessary to promote the growth of impurities and to be difficult to occlude the impurities. Examples of organic solvents that meet these conditions include ketones, alcohols, and ethers.
Examples of ketones include methyl ethyl ketone,
Examples of alcohols include acetone, etc.
Examples include methanol, ethanol, and isopropanol, and examples of ethers include tetrahydrofuran. It is sufficient that the amount of these solvents used is at least the amount that dissolves the biphenol. The activated carbon used in the present invention may be in the form of granules or powder. The purpose of activated carbon treatment is to remove colored impurities and to efficiently separate and remove impurities that are difficult to dissolve in organic solvents. The amount of activated carbon used in the present invention is preferably 0.01 to 50% by weight based on biphenol. The temperature of the activated carbon treatment is preferably above room temperature and below the boiling point of the solvent. As a method of activated carbon treatment, a method may be adopted in which crude biphenol is dissolved in an organic solvent and activated carbon is added at the same time. Further, an adsorption tower filled with granular activated carbon may be used, and the present invention does not limit the treatment method. Of course, if the colored content of the crude biphenol is small, the next operation may be carried out without using activated carbon. Next, the crude biphenol solution containing insoluble impurities or the activated carbon-treated solution thereof can be subjected to solid-liquid separation with a small excess resistance by a conventional method. In the present invention, an ion exchange resin is added to a solution of crude biphenol in an organic solvent or a solution of the solution treated with activated carbon, stirred, and then the resin is filtered.Of course, a packed bed of ion exchange resin is provided, A liquid may be passed through this packed bed. As the ion exchange resin, commercially available products such as strongly acidic cation exchange resins, weakly acidic cation exchange resins, weakly basic anion exchange resins, and weakly basic anion exchange resins can be used. The mechanism by which impurities are removed by ion-exchange resin treatment is generally considered to be the mechanism in which cations or anions are ion-exchanged in a solution.
In the present invention, since even a weakly basic anion exchange resin is sufficiently effective, the mechanism of action is complex and cannot be easily discussed. The larger the amount of ion exchange resin used in the present invention, the better the effect, but even a small amount is sufficient. Generally, the amount used is preferably 0.001% by weight or more based on biphenol, and particularly preferably 0.1% or more. . This usage amount also applies when using an ion exchange resin as a packed bed. Further, although an ion exchange resin is used in the present invention, an ion exchange liquid may also be used, as is clear from its expected complicated mechanism of action and effects. When using an ion exchange solution, it is preferable to use it after confirming that the exchange solution is sufficiently dissolved and that biphenol is also sufficiently dissolved. EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. Note that the percentages shown in the examples are percentages by weight unless otherwise specified. Example 1 170 g of crude 4,4'-dihydroxydiphenyl obtained by diphenyl alkaline fusion method
Dissolved in 1500g of methanol and added 15g of activated carbon to this.
g was added thereto, and the mixture was stirred at 50 to 60°C for 3 hours. Aspirate this solution and add Amberlyst 15 to the resulting solution.
and Amberlyst A-21 ion exchange resin (manufactured by Rohm and Haas, USA), 10 each.
The ion exchange resin was separated by suction filtration. By concentrating and crystallizing the obtained liquid, 4・4'-
150 g of dihydroxydiphenyl was obtained. As a result, the yield was 80.6 mol%, the purity of the product was 96%, and the Na content was 24 ppm. The polyester obtained using this biphenol as a raw material exhibited almost no coloration and exhibited extremely high thermal stability. Example 2 2 kg of crude 4,4'-dihydroxybiphenyl obtained under the same conditions as Example 1 was added to a
The mixture was placed in a reactor equipped with a stirrer, and 17 kg of methanol was added thereto to dissolve 4,4'-dihydroxybiphenyl. 170 g of activated carbon was added to this solution and stirred at 50 to 60°C for 3 hours. Thereafter, this solution was filtered under suction to separate the activated carbon, and then 37 g each of Amberlyst 15 and Amberlyst 21 were added to the liquid, and the mixture was stirred at 50 to 60°C for 1 hour. Thereafter, this solution was filtered under suction to separate the ion exchange resin, the liquid was concentrated to about 7 kg, and the concentrated liquid was cooled to 40°C to precipitate crystals. After separating the obtained crystals by suction filtration, 60-70
After drying at ℃ for 20 hours, 1.3 kg of 4,4'-dihydroxybiphenyl was obtained. The purity of the product was 99.0%, with 6 ppm Na. The polyester obtained using this biphenol as a raw material exhibited no coloration and exhibited extremely high thermal stability. Examples 3 to 5 The results shown in Table 1 were obtained by carrying out the same operations as in Example 1, except that acetone, methyl ethyl ketone, tetrahydrofuran, etc. were used as the solvent instead of methanol.

[Table] All of the polyesters obtained using these biphenols showed almost no coloration and exhibited extremely high thermal stability. Examples 6 to 8 Instead of the crude 4,4'-dihydroxydiphenyl obtained by the alkaline fusion method of diphenyl in Example 1, 4,4' obtained from 2,6-di-tert-butylphenol was used. -dihydroxydiphenyl (method B), 4,4'-dihydroxydiphenyl obtained from dibromubiphenyl (method C), p
- Example 1 except that 4,4'-dihydroxydiphenyl obtained from chlorphenol (method D) was used.
Purification was carried out in exactly the same manner as above, and the results shown in Table 2 were obtained.

[Table] All of the polyesters obtained using these diphenols showed almost no coloration and exhibited extremely high thermal stability. Example 9 In Example 1, 3,5,3',5'-tetra- was used instead of crude 4,4'-dihydroxydiphenyl.
Purification was carried out in exactly the same manner as in Example 1, except for using tert-butyl-4,4'-dihydroxydiphenyl, to obtain purified 3,5,3', with a yield of 84.1%.
5'-tetra-tert-butyl-4,4'-dihydroxydiphenyl was obtained. The purity of the product was 96% with 16 ppm Al. Examples 10 and 11 Table 3 shows the results when Amberlyst 15 and Amberlyst A-21 were used alone as the ion exchange resins in Example 1.

[Table] The polyesters obtained using these diphenols as raw materials showed almost no coloration and exhibited extremely high thermal stability.

Claims (1)

[Claims] 1. General formula [In the formula, R represents hydrogen or an alkyl group. ] The boiling point of crude P・P'-biphenols expressed as
A method for purifying crude P·P'-biphenols, which comprises dissolving them in an organic solvent at 100°C or lower, treating the resulting solution with an ion exchange resin, and then crystallizing them. 2. The method according to claim 1, wherein a solution of crude P·P'-biphenols in an organic solvent is treated with activated carbon. 3 Claims in which the crude P/P'-biphenols are crude P/P'-biphenols containing as impurities one or more of alkali metal compounds, alkaline earth metal compounds, aluminum group compounds, or sulfur oxides. The method described in paragraph 1. 4. The method according to claim 1, wherein the organic solvent is at least one selected from ketones, alcohols, and ethers. 5. The method according to claim 3, wherein the sulfur oxide is sulfonic acid, sulfuric acid, or a salt thereof. 6. The method according to claim 1, wherein the ion exchange resin is a cation exchange resin, an anion exchange resin, or a mixture thereof.