JPH0446253B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides 2,2-bis(4-hydroxy-3
-Methylphenyl)propane (hereinafter referred to as bis-cresol A).

More specifically, the present invention relates to a method for producing high-purity bis-cresol A, which comprises recrystallizing crude bis-cresol A obtained by reacting o-cresol with acetone or a derivative thereof using o-cresol.

Biscresol A, like 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as biscresol A) produced from phenol and acetone, is used as a raw material for polycarbonate, epoxy resin, aromatic polyester, etc. It will be done.

For such uses, highly pure substances are used and must be purified to a high degree.

(Prior Art) Conventionally, several known methods have been applied to produce biscresol.

Most commonly, similar methods are applied as for the production of bis-cresol A, e.g.
The crude product was obtained by condensation dehydration of cresol and acetone in the presence of an acid catalyst, and then the catalyst and excess o-
Cresol is removed and, if necessary, the product is crudely purified by methods such as distillation and recrystallization from an organic solvent. As a specific example of such a method, in USP 2211070 (1941) by Wm.
A method of recrystallization with carbon tetrachloride is described.

In addition, Japanese Patent Publication No. 47-50616 describes a method for producing o-cresol, o-tolyl acetate, and acetone as raw materials, and further describes
No. 55-151512 describes o-cresol and 1,1
- diacetoxypropane is disclosed.

Furthermore, JP-A No. 47-50616 and JP-A-55-
No. 151512 describes that biscresol A is isolated by treatment in the same manner as in the production of bisphenol A. In this method, the crystals of the adduct of phenol and bisphenol A are taken out, and then the phenol is removed from the adduct by a method such as vacuum distillation under reduced pressure to isolate bisphenol A. .

A similar method was used by Shimauchi (Journal of the Chemical Society of Japan 1982(8) p1363)
~1370), but here, refined biscresol is obtained by further recrystallizing the crude biscresol obtained by the above method with benzene.

Any of these methods requires a long purification process, uses an organic solvent and requires a recovery process, and is extremely complicated to implement industrially.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for producing biscresol that is simple and highly effective in purification.

(Means for Solving the Problems) In order to achieve the above object, the present inventors have made extensive studies and found that bis-cresol A does not form an addition product with o-cresol, and that bis-cresol A does not form an addition product with o-cresol.
Bis-cresol A can be separated from other by-products by utilizing the difference in solubility in o-cresol, and the resulting bis-cresol A crystals contain almost no impurities other than the mother liquor attached to the crystals, and can be easily The inventors have discovered that highly pure bis-cresol A can be produced by this method, and have arrived at the present invention.

That is, the present invention deals with the production of crude 2,2-bis(4-hydroxy-3-methylphenyl)propane from o-cresol and acetone or its derivatives. This method recrystallizes methylphenyl)propane with o-cresol and isolates it to produce highly pure 2,2-bis(4-hydroxy-3-methylphenyl)propane.

The present invention will be explained in detail below.

The crude 2,2-bis(4-hydroxy-3-methylphenyl)propane used in the method of the present invention is not particularly limited as long as it can be produced by any method. Most commonly, excess o-cresol is removed under the action of o-cresol or its derivatives, such as o-tolyl acetate and acetone or its derivatives, such as 1,1-diacetoxypropane and its acid catalyst. obtained in the presence of It can also be produced from p-isopropenyl-o-cresol and a stoichiometrically excess amount of o-cresol.

After completion of the reaction, the reaction product liquid can be subjected to purification as it is, but, of course, crude bis-cresol A obtained by isolation by a conventional method may also be used.

Furthermore, biscresol A containing impurities, which cannot be obtained with sufficient purity using other purification methods, can be omitted.
- May be dissolved in cresol.

The amount of o-cresol required to purify crude bis-cresol A may be selected within a range such that the content of crude bis-cresol A in o-cresol is 20 to 60% by weight.

Since bis-cresol A has a slight solubility in o-cresol, the higher the concentration of bis-cresol A, the greater the amount of precipitated crystals. The concentration of the o-cresol solution at the time of crystallization is controlled within the temperature range in which bis-cresol A crystals do not precipitate within the above bis-cresol A concentration range. For example, when the concentration of biscresol A is 20%, the temperature is 50℃ or higher, and when the concentration of biscresol A is 60%, the temperature is 80℃ or higher.
℃ or higher.

The o-cresol solution of crude bis-cresol A is
It may or may not contain water.

When the crude bis-cresol A to be treated is a reaction product liquid that is subsequently treated, the reaction for producing the crude bis-cresol A is preferably carried out with a slight excess of o-cresol. That is, it is more preferable to carry out the reaction at a ratio of bis-cresol A to unreacted o-cresol of 1:2 to 1:10 mol/mol. After the reaction,
If the catalyst is omitted or if a reaction fixed bed catalyst layer is used, an o-cresol solution of bis-cresol A can be obtained directly.

Crystallization from solution can be carried out using any crystallization method.

As one method, o-
Crystals can be obtained by adding water to a cresol solution and cooling it by distilling it under reduced pressure. Water may be added to the o-cresol solution of bis-cresol A before crystallization, or may be added to the slurry-like mixture that is undergoing crystallization.
The latter method is advantageous when crystallization is carried out continuously. In this case, the operating pressure is 20-100mmHg,
Water containing 2 to 20% water by weight or an equivalent amount of water.
Pure bis-cresol A crystals can be obtained by adding the o-cresol mixture and cooling to a temperature in the range of 25 to 70°C.

For cooling for crystallization, heat removal by evaporation of reaction product water, unreacted acetone, and biscresol itself can be used.

The crystals thus obtained are separated from the mother liquor by conventional separation methods, ie, filtration, centrifugation, etc.

The mother liquor can be dehydrated if necessary, further concentrated if necessary, and used as a raw material for biscresol A newly produced by the method of the present invention.

The separated crystals can be used as products as they are depending on the purpose. Water, o if necessary
- It can be made into a product after washing with a solvent such as cresol, aromatic hydrocarbon, aliphatic hydrocarbon, etc. and then drying. In some cases, after dissolving the crystals and completely removing the remaining adhering mother liquor by heating, vacuuming, stripping, etc., it is possible to take out the desired product form.

The bis-cresol A thus obtained is pure white and can be used directly in applications requiring high purity bis-cresol, including the production of polycarbonate resins.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 162 g (1.5 mol) o-cresol, acetone
14.5 g (0.25 mol) of the mixture was mixed, and a condensation reaction was carried out at 45° C. for 8.5 hours while hydrogen chloride was further blown into the mixture. When the reaction mixture was left as it was at room temperature, precipitation of crystals was observed on the 6th day. The reaction mixture was heated to 120° C. under reduced pressure to dissolve the entire amount of the crystals while removing hydrochloric acid and water produced by the reaction. This dehydrochloric acid solution was cooled to precipitate crystals. After filtering the crystals, they were washed with three times the amount of benzene to obtain pure biscresol. As a result of high-performance liquid chromatography analysis, the purity of the crystals was 99.4%.
and contained 0.6% isomer.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1. The reaction mixture was left at room temperature, but on the 10th day
A crystal of g was obtained. After filtering this crystal, 3
The purity of the crystals obtained by washing with twice the amount of benzene is 97.1
It was %.

Example 2 In the same manner as in Example 1, crude bis-cresol was mixed and melted with an equal amount of o-cresol, and the mixture was cooled to room temperature to obtain crystals. Pure biscresol was obtained with a yield of 85%. As a result of analysis, the purity was 99.6%.

Example 3 O-cresol, acetone, and bis-cresol were produced in the same molar ratio as in Example 1.

Bis-cresol 30% Isomers 2.3% Other impurities 1.8% o-cresol 57.9% This bis-cresol solution was charged to a crystallization tank operated at 30 mmHg at a flow rate of 400 kg/hour at 90°C, and further to the crystallization tank. added water at a rate of 30Kg/hour. The temperature inside the crystallization tank was kept constant at 35°C. A liquid containing crystals was continuously extracted from the crystallization tank and filtered.
The crystals were continuously washed with o-cresol, and the composition of the obtained crystals was as follows.

Bis-cresol 92.7% Isomers 0.2% Other impurities 7.1% Only traces of o-cresol detected O-cresol was removed from the crystals using a steam trip to obtain pure white bis-cresol with a purity of 99.8%.

(Effects of the Invention) As described in detail above, the present invention provides a method for producing biscresol A with high purity.

This method is characterized by recrystallizing the product using raw materials, which makes it possible to simplify the process and makes industrial contributions such as eliminating the need to use other organic solvents in the manufacturing process. big.

Claims (1)

[Claims] 1 When producing 2,2-bis(4-hydroxy-3-methylphenyl)propane from o-cresol and acetone or its derivatives, the crude 2,2-bis(4-hydroxy-3-methylphenyl)propane produced is A method for producing high-purity 2,2-bis(4-hydroxy-3-methylphenyl)propane, which comprises recrystallizing from o-cresol.