JPS5842186B2 - Purification method of dihydroxydiphenyl sulfone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying dihydroxydiphenyl sulfone (hereinafter referred to as bisphenol-8).

As a method for producing hisphenol-8, generally,
Known methods include reacting phenol with a sulfonating agent such as concentrated sulfuric acid, fuming sulfuric acid, sulfuric anhydride, phenolsulfonic acid, and chlorosulfonic acid.

Since all of these reactions are carried out at a high temperature of 140 to 250° C. for a long time, it is impossible to avoid the production of a reddish brown to blackish brown cool substance as a side reaction product.

Moreover, this substance has very similar solubility in various solvents to bisphenol-8, the main product, and is therefore very difficult to separate, causing coloration in the final product.

Bisphenol-8 has heat resistance, oxidation resistance, and light stability due to the specificity of its diphenylsulfone bond. Therefore, in recent years, bisphenol-A has been used in the field of engineering plastics such as polyester resins, epoxy resins, and polycarbonate resins. Its use as an alternative is developing.

However, resin products manufactured using bisphenol-8 containing impurities, especially coloring substances, are colored yellowish brown.
Since transparency is also lost, the field of application as a plastic is limited.

For this reason, pure bisphenol-8 containing no coloring substances is required as a raw material for manufacturing engineering plastics.

Conventionally, methods for purifying colored bisphenol-8 include methanol or alkaline aqueous solutions (methods in which bisphenol-8 containing colored substances are dissolved, and then activated carbon is added to this solution to remove the colored substances by adsorption). (described in Examples of Japanese Patent Publication No. 38-5274 and Japanese Patent Publication No. 51-36264).

However, these adsorption removal methods using activated carbon cannot sufficiently remove colored substances from the liquid, so bisphenol-8
The solution still had a reddish-purple color, and the whiteness of bisphenol-8 crystallized and recovered from the solution could not be said to be fully satisfactory.

In JP-A-50-111045, colored bisphenol-8 is dissolved in an aqueous phenol solution, the colored substance is extracted and transferred to the phenol phase, and then the bisphenol-8 dissolved in the aqueous phase is crystallized and recovered. A method for purifying bisphenol-8 is shown.

However, in this method, it is necessary to control the concentration of phenol and bisphenol-8 in the solution and the temperature of the solution quite accurately, and there are many difficulties in industrial implementation.

In addition, in Japanese Patent Publication No. 42-3005, bisphenol-8 containing a colored substance is dissolved in water, a fatty higher alcohol is added thereto, and the mixture is heated and stirred under pressure at 120°C or higher, thereby dissolving the colored substance in the alcohol layer. However, it is not suitable for industrial implementation because it requires stirring for a long time under pressure and high temperature to sufficiently extract and remove colored substances.

The present inventors have discovered that bisphenol with high whiteness can be applied industrially advantageously by overcoming the difficulties of these conventional methods.
Various studies have been conducted regarding the manufacturing method of No. 8.

As a result, we discovered that as a new method for separating and removing colored substances from bisphenol-8 containing colored substances, it is possible to decolorize the colored substances contained in bisphenol-8 by treating them with an inorganic peroxide. Based on this knowledge, the present invention was completed.

That is, the present invention provides bisphenol-containing colored substances produced by the reaction of phenol and a sulfonating agent.
The present invention relates to a method for purifying bisphenol-8, which comprises dissolving bisphenol-8 in an alkaline aqueous solution, adding an inorganic peroxide to the solution to make the solution colorless, and then crystallizing and separating crystals.

The purification effect can be further improved by concurrently using a sequestering agent during the above operations of the present invention.

Bisphenol-8 containing a colored substance that can be subjected to the method of the present invention is obtained by reacting phenol with a sulfonating agent, i.e., by reacting phenol with a known sulfonation method such as concentrated sulfuric acid, oleum, sulfuric anhydride, phenolsulfonic acid, chlorosulfonic acid, etc. Any material obtained by reaction with an agent can be used.

When carrying out the method of the present invention, the dissolution of bisphenol-8 containing a colored substance in an alkaline aqueous solution, the decolorization treatment with an inorganic peroxide, and the crystallization separation of crystals are performed under reduced pressure, normal pressure, or increased pressure. However, generally normal pressure is sufficient.

In addition, an inorganic peroxide and preferably a sequestering agent are added to the bisphenol-8 dissolved solution to decolorize the solution, but in order to effectively perform the decolorization operation in a short time, the temperature of the solution is kept at 60°C.
Preferably, the mixture is heated to the boiling point.

After decolorization, any method of cooling, concentration, or neutralization may be used to crystallize bisphenol-8 crystals from the solution.

Further, as for the method of separating the crystallized crystals, appropriate methods such as suction filtration, pressurized filtration, and centrifugation can be used.

Examples of the alkaline aqueous solution used in the method of the present invention include a caustic soda aqueous solution, a sodium carbonate aqueous solution, and a caustic potassium aqueous solution.

The concentration of alkali is such that the pH after dissolving bisphenol-8 is 8.
It is preferable to adjust it so that it is between 10 and 10.

Inorganic peroxides used in the method of the present invention include hydrogen peroxide, sodium percarbonate, and soda percarbonate.

The amount of the inorganic peroxide to be used is 0.1 to 5% by weight based on the weight of bisphenol S to exhibit sufficient effects.

Sequestering agents to be used in combination include nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, etc., and the amount of these used is 0.01 to 1.0% by weight based on the weight of bisphenol-8 to exhibit sufficient effects. It is possible.

Next, the present invention will be explained in more detail with reference to Examples.
The scope of utility of the present invention is not limited by the following examples.

In addition, the degree of coloring of bisphenol-8 in the examples is AP
It is indicated by the Hazen color number measured with an HA-meter.

Comparative Example 8100 g of bisphenol containing a colored substance obtained by the reaction of phenol and concentrated sulfuric acid was heated to 50'C.
% caustic soda aqueous solution and dissolve it with stirring, add 0.5 g of activated carbon, and further maintain the temperature at 50 ° C.
After stirring for 0 minutes, the activated carbon was removed from the furnace.

The filtrate was neutralized with sulfuric acid to pH=4, and after cooling, the precipitated crystals were separated in a furnace and dried.

Example 1 8,100 g of bisphenol containing a colored substance obtained by the reaction of phenol and concentrated sulfuric acid was added to a 2% aqueous solution of caustic soda heated to 50°C, dissolved with stirring, and then 35% hydrogen peroxide was added. Add 2g and further raise the temperature to 80℃,
The mixture was stirred at this temperature for 20 minutes to decolorize it.

After decolorization, the decolorization solution was neutralized to pH=4 with sulfuric acid, and after cooling, the precipitated crystals were separated in a furnace and dried.

Example 2 The method of Example 1 was repeated, except that 3 g of soda percarbonate was used instead of hydrogen peroxide.

Example 3 The method of Example 1 was repeated using 3 g of ammonium persulfate instead of hydrogen peroxide.

Example 4 In the method of Example 1, 0.1 g of sodium ethylenediaminetetraacetate was used together with hydrogen peroxide.

Table 1 shows the Hazen color numbers of the decolorized Bisfe/-Roux S obtained in Comparative Examples and Examples 1 to 4.

Claims (1)

[Claims] 1. 4,4'-dihydroxydiphenyl sulfone containing a colored substance produced by the reaction of phenol and a sulfonating agent is dissolved in an alkaline aqueous solution and treated with an inorganic peroxide. Features: A method for purifying 4,4'-dihydroxydiphenyl sulfone. 2. 4,4'-Dihydroxydiphenyl sulfone containing a colored substance produced by the reaction of phenol and a sulfonating agent is dissolved in an alkaline aqueous solution and treated with an inorganic peroxide in the presence of a sequestering agent. A method for purifying 4,4'-dihydroxydiphenylsulfone, characterized in that: