JPH0478609B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a novel method for purifying high-purity 4,4'-dihydroxydiphenylsulfone from crude 4,4'-dihydroxydiphenylsulfone in high yield. Conventional technology 4,4'-dihydroxydiphenyl sulfone (hereinafter referred to as 4,4' body) has excellent heat resistance, oxidation resistance, light stability, etc., so it has recently been used in polyester resins, epoxy resins, and polycarbonates. It has come to be widely used in the field of polymer chemical industry, such as resins and polyethersulfone resins. In this case, synthesis is performed using 4,4'-form as a raw material containing impurities such as 2,4'-dihydroxydiphenylsulfone (hereinafter referred to as 2,4'-form) and trihydroxytriphenyldisulfone (hereinafter referred to as "tri-form"). The resulting polymer product tends to have a lower molecular weight and lower mechanical properties, and this tendency becomes more pronounced as the amount of impurities such as 2,4' and tri-isomers increases. Therefore, 2,
There is a demand for the supply of highly pure 4,4'-isomers from which impurities such as 4'-isomers and tri-isomers have been removed as much as possible. In addition, the 4,4′ body is a coupler raw material for color photography,
It is also useful as a color developer for heat-sensitive recording paper, and in this case as well, high purity is desirable. Industrially, the 4,4' isomer is mainly produced by a dehydration reaction between phenol and a sulfonating agent such as sulfuric acid, and the reaction product contains 2,4' as an impurity.
Contains sulfones such as 4'-isomers and tri-isomers and other sulfonic acids, etc., and the purity of 4,4'-isomers in the 4,4' crude product after removing sulfonic acids, etc. is usually 70 to 80%. It is about % by weight. In addition, a method has been developed to suppress the by-product of 2,4'-isomer and obtain highly pure 4,4'-isomer. For example, a method of obtaining highly pure 4,4' isomer by precipitating the 4,4' isomer produced by a dehydration reaction and isomerizing the by-product 2,4' isomer into 4,4' isomer.
No. 55-8972) has been proposed. In this case, the purity of the 4,4' product in the crude 4,4' product obtained by removing sulfonic acids and the like from the reaction product is usually about 90 to 95% by weight. However, due to the recent demand for higher quality resins, it has come to be desired that the purity of the 4,4' compound for the various uses mentioned above be about 97% by weight or more. Therefore, it is necessary to further purify those produced by the former method, and it is desirable to further refine those produced by the latter method. Examples of methods for purifying the 4,4′-isomer include o-dichlorobenzene-phenol (Japanese Patent Publication No. 51-36264),
o-dichlorobenzene-acetic acid (Special Publication No. 57-48152
Treatment methods using various mixed organic solvents such as o-dichlorobenzene-ethyl acetate (Japanese Patent Publication No. 57-48153), and o-dichlorobenzene-alcohol (Japanese Patent Publication No. 58-2234) have been proposed. ing. However, since all of these methods use organic solvents, there are problems in that they are inconvenient to handle, pose a danger to work hygiene, and pollute the environment. In addition, conventional purification methods that do not use organic solvents include dissolving the 4,4' crude product in an alkaline aqueous solution such as sodium hydroxide, treating it with activated carbon, and then adding an acid such as sulfuric acid in an amount greater than the neutralizing amount. In addition, a method of precipitating the 4,4' isomer has been used. This method is
The 4,4' isomer is hardly soluble in water, but it takes advantage of the property that it easily dissolves in the aqueous solution of a basic substance as a mono- or di-metal salt. however,
Although this method can remove sulfonic acids, it can hardly remove 2,4'- and tri-sulfones, and as shown in the comparative example below, the purity of the purified product is insufficient, and it does not meet the above requirements. cannot be answered at all. Problems to be Solved by the Invention The purpose of the present invention is to solve the problem without using an organic solvent.
Moreover, the present invention aims to provide a novel purification method that can obtain a highly purified 4,4'-form with a high purification yield (yield relative to the 4,4'-form before purification) and that fully meets the above-mentioned needs. be. Means for Solving the Problems As a result of intensive research to achieve the above object, the present inventor has discovered that when a crude 4,4' product is dissolved in an aqueous solution of a basic substance and then salted out, high purity 4,4' ，
We discovered the unique fact that a 4' monometallic salt is precipitated, and by treating it with an acid, we can obtain 4,4 with a high purification yield of usually over 85% and a high purity of over 99% by weight. It was found that ′ body can be obtained. The fact that the 4,4'-isomer can be salted out as a highly pure monometallic salt under specific conditions is based on the common knowledge that 4,4'-isomer mono- and dimetallic salts are easily soluble in water. This is completely unexpected for those skilled in the art. The present invention was completed based on this new knowledge. That is, the present invention involves dissolving a 4,4' crude product in an aqueous solution of a basic substance, salting out to precipitate and separate a 4,4' monometal salt, and then treating this with an acid. The present invention relates to a method for purifying a 4,4′ body characterized by the following. In this specification, monometallic salt means monoalkali metal salt, mono1/2 alkaline earth metal salt, and the like. The method of the present invention can be applied to various 4,4' synthesis reaction products, 4,4' crude products of any purity, including products from which sulfonic acids have been removed, and commercially available 4,4' products. It can also be applied to the purification of In the present invention, the crude 4,4' product is first dissolved in an aqueous solution of a basic substance, usually under stirring. As the basic substance, hydroxides and carbonates of alkali metals such as sodium and potassium, alkaline earth metals such as calcium and magnesium, etc. can be preferably used. Particularly preferred are sodium hydroxide, sodium carbonate, and the like. The amount of the basic substance to be used is approximately 1 equivalent or more and approximately 2 equivalents per mole of sulfones such as 4,4', 2,4', and tri-isomers, in addition to the neutralizing amount of strong acids such as sulfonic acids. The following is appropriate. If the amount is less than this range, free 4,4,
This is not preferable because the 4'-isomer is mixed in and the crystal form deteriorates, which tends to reduce the impurity removal effect. Further, if the amount exceeds this range and the salting-out agent is added as is, a large amount of 4,4' dimetal salts that are not salted out tend to be produced, resulting in a decrease in yield, which is not preferable. However, the use of the basic substance in an amount exceeding 2 equivalents per mole of sulfones such as 4,4' sulfones does not pose any problem and is an advantageous embodiment of the present invention. That is, by using an excess of more than 2 equivalents of a basic substance to create a dissolved state in which a large amount of 4,4' dimetal salts that are not salted out are produced, activated carbon treatment, etc., can be suitably performed if necessary. Then, an acid is added to convert the dimetal salt into a monometal salt, and at the same time a salting-out agent is generated, and if necessary, a salting-out agent can be further added to salt out the monometal salt. In the above-mentioned dissolution treatment of the 4,4′ crude product,
The processing liquid exhibits a solution or suspension state depending on the amount of basic substance and water used. In a suspended state, the liquid phase generally consists of a 4,4' monometallic salt and a small amount of 4,4' monometallic salt.
The 4' dimetal salt is dissolved, and the solid phase is mainly composed of the 4,4' monometal salt that becomes supersaturated and precipitates after dissolution, and the subsequent salting out removes the 4,4' dimetal salt from the liquid phase. It is thought that the 4′ monometallic salt further precipitates and the crystals grow. The amount of water used during dissolution treatment can be selected from a wide range, but it is usually 1.0 to
Approximately 8.0 times the weight is appropriate. If the amount of water is less than this range, a suspension state with a large amount of solid phase will occur, resulting in poor fluidity and stirring will tend to become difficult, and if the amount of water is more than this range, the purification yield will tend to decrease. I don't like it because it is. A particularly preferable amount of water is 1.3 to 3.0 for the 4,4′ crude product.
It is about twice the weight. Further, the temperature during the dissolution treatment is not particularly limited, but it is advantageous to set it to about 40° C. to the boiling point in that the production rate of the 4,4′ monometallic salt can be increased. Next, the solution or suspension obtained by treating the crude 4,4' product as described above is salted out, usually with stirring, to precipitate the monometallic salt of the 4,4' product. This typically results in a purity of 98
The 4,4' monometallic salt with a high purity of about % by weight or more is usually precipitated in a high yield of 87% or more based on the 4,4' monometal salt in the crude raw material. This fact is
This was discovered for the first time by the present inventor. Salting out is carried out by adding a salting out agent, adding an excess of the basic substance and adding an acid such as hydrochloric acid or sulfuric acid to generate a salting out agent, or using a combination of these methods. It will be done. As the salting-out agent, chlorides and sulfates of alkali metals such as sodium and potassium, alkaline earth metals such as calcium and magnesium, etc. can be preferably used. Further, the amount of the salting-out agent to be used can be selected from a wide range, and it is usually appropriate to set the amount to be at least 2% by weight and at most the saturation concentration. If the amount is less than this range, the salting-out effect will be low and the yield will decrease, which is not preferable. Also,
If the concentration exceeds the saturation concentration, crystals of the salting-out agent will precipitate, which is not preferable. The preferred usage amount of the salting-out agent is usually 4
The amount is approximately 15% by weight. The temperature at which the salting-out agent is added is not particularly limited, but it is advantageous to set it to about 40°C to the boiling point in order to improve the crystal form of the 4,4′ monometallic salt and improve the yield and purity. It is. After adding salting out agent, at that temperature
It may be aged for about 0.2 to 12 hours. Next, the precipitated 4,4' monometallic salt is separated by filtration and, if necessary, washed appropriately to obtain a highly purified 4,4' monometallic salt. Next, this is usually treated with an acid to obtain a free 4,4' compound. Acid treatment can be carried out according to a conventional method, and the 4,4' monometal salt is dissolved in water or an alkaline aqueous solution, treated with activated carbon if necessary, and then an acid such as sulfuric acid or hydrochloric acid is added. The pH is adjusted to about 3 to 6, and the precipitated 4,4' compound is separated by filtration, and the reaction is carried out almost quantitatively. In this way, the desired 4,4' compound can be purified with high purification yield and high purity. Effects of the Invention According to the method of the present invention, the following particularly remarkable effects are achieved. (1) Easy to handle because no organic solvent is used.
There are no occupational hygiene or environmental problems. (2) Usually, the 4,4′ isomer can be obtained with a high purification yield of 85% or more and a high purity of 99% by weight or more.
This can fully meet the demands of the industry. (3) Compared to conventional methods, a large amount of purification can be efficiently carried out using a small amount of liquid. Additionally, the equipment can be made compact and workability is good. Examples Hereinafter, the present invention will be described in more detail with reference to reference examples, examples, and comparison columns. Reference Example 1 A 4,4' crude product was produced by the method described in Japanese Patent Publication No. 55-8972. That is, a mixture of 290 g of phenol, 146 g of 98% by weight sulfuric acid, and 150 g of o-dichlorobenzene (ODCB) was heated with stirring. The reaction solution boiled around 150°C, and reaction product water began to distill out along with ODCB. The distillate is condensed, the ODCB phase is continuously returned to the reaction system, and from the point when the liquid volume of the aqueous phase reaches 52 ml, the reaction temperature is maintained at 175 to 185°C, and the produced water and The ODCB containing a small amount of phenol was recovered by distillation over a period of 4 hours until the reaction product was dried to dryness. The analysis results of the dried reaction product obtained here by high performance liquid chromatography showed that 84.6% by weight of the 4,4′ isomer;
2.0% by weight of 2,4'-isomer, 4.5% by weight of tri-isomer, and 8.9% by weight of other sulfonic acids. Example 1 100 g of the reaction dry product, which is the crude 4,4' product obtained in Reference Example 1, was mixed with 155 g of water and 18.1 g of sodium hydroxide.
(The amount necessary for neutralizing the sulfonic acid content and the 4,4' form, 2,
1.2 for the sum of 4′ and tri-sulfones
Corresponds to the sum of double equivalent amounts. ), and the temperature was raised to 95°C while stirring. The liquid was not completely dissolved and remained in a suspended state. Next, 10 g of common salt was added, and the mixture was kept at the same temperature for 30 minutes to age and then cooled. After keeping warm at 50℃ for 1 hour,
The precipitate was collected and washed with 50 ml of 5% brine to give 84.0 g of 4,4' monosodium salt (purification yield: 91.3
%) was obtained. The obtained 4,4' monosodium salt was treated with hydrochloric acid and analyzed by high performance liquid chromatography. The results are shown in Table 1. The 4,4′ monosodium salt obtained above was dissolved in water.
The solution was dissolved in 900 ml, and 78% by weight sulfuric acid was added at a temperature of 90 to 95°C to neutralize the pH to 4.0 to precipitate the 4,4' isomer.
After cooling to 40°C, it was taken and dried to obtain 76.6 g of a purified 4,4' product. The purification yield was 90.4% (based on the 4,4' product in the starting material). The analysis results by high performance liquid chromatography were as shown in Table 1. Example 2 Example 1 except that 15 g of anhydrous sodium sulfate was used in place of 10 g of common salt as a salting-out agent in Example 1.
Salting out in the same manner as 4,4′ monosodium salt
83.2 g (purification yield: 90.4%) was obtained, which was further treated with sulfuric acid in the same manner to obtain 75.9 g of a purified 4,4' product. The purification yield was 89.5%, and the results of analysis by high performance liquid chromatography were as shown in Table 1. Example 3 Reaction dried product as 4,4' crude product obtained in Reference Example 1
100g, 280g of water and 31.6g of sodium hydroxide (corresponds to the sum of the amount required to neutralize the sulfonic acid content and the amount equivalent to 2.1 times the total amount of sulfones such as 4,4'-isomers). In addition, the temperature was raised to 95°C while stirring. The liquid was completely dissolved. Next, after gradually adding 24.1 g of 78% sulfuric acid,
After cooling and keeping at 50°C for 1 hour, the precipitated crystals were collected and washed with 5% by weight sodium sulfate water.
4′ monosodium salt 81.0g (purification yield 88.0%)
I got it. As a result of analysis of the obtained 4,4' monosodium salt by high performance liquid chromatography, the composition ratio was as shown in Table 1. The 4,4' monosodium salt obtained above was
When treated with sulfuric acid in the same manner as in Example 1, 73.9 g of a purified 4,4' product was obtained. The purification yield is 87.3%,
The analysis results by high performance liquid chromatography are
It was as shown in Table 1. Example 4 The composition of a commercially available crude product of 4,4' body was analyzed by high performance liquid chromatography, and it was found that 4,4' body,
2,4' body and tri body are 82.6% by weight and 14.0% by weight, respectively.
It was 3.4% by weight. 100 g of this crude product was added to 160 g of water and 33.2 g of sodium hydroxide (2.1 times equivalent to the total amount of sulfones such as 4,4' sulfones), and the temperature was raised to 97° C. with stirring.
The liquid was not completely dissolved and remained in a suspended state. Next, after gradually adding 25.1 g of 78% sulfuric acid,
After cooling and keeping at 50°C for 1 hour, the precipitation results were taken and washed with 5% by weight sodium sulfate water.
4′ monosodium salt 80.4g (purification yield 87.4%)
I got it. As a result of analysis of the obtained 4,4' monosodium salt by high performance liquid chromatography, the composition ratio was as shown in Table 1. The 4,4' monosodium salt obtained above was
When treated in the same manner as in Example 1, 71.5 g of a purified 4,4' product was obtained. The purification yield is 85.8% by weight,
The analysis results by high performance liquid chromatography are
It was as shown in Table 1.

【table】

[Table] Comparative Example 1 100 g of the 4,4' crude product obtained in Reference Example 1, 31.6 g of sodium hydroxide, and 280 g of water were dissolved at elevated temperatures with stirring, and 48.0 g of 78% by weight sulfuric acid was added at 95°C. PH=4
After cooling and keeping warm at 50℃ for 1 hour,
Separately, 89.9 g of 4,4' compound was obtained by drying. Yield is 99.3%
The results of high-performance liquid chromatography analysis show that the 4,4′ form is 93.4% by weight, the 2,4′ form is 1.7% by weight,
The chicken body content was 4.9% by weight.

Claims (1)

[Claims] 1 The crude product of 4,4'-dihydroxydiphenylsulfone is dissolved in an aqueous solution of a basic substance and then salted out to precipitate and separate the monometallic salt of 4,4'-dihydroxydiphenylsulfone. A method for purifying 4,4'-dihydroxydiphenyl sulfone, which is characterized by acid treatment.