JPH03206073A - Production of high-purity 4,4'-dihydroxydiphenylsulfone - Google Patents

Abstract

PURPOSE:To obtain high-purity 4,4'-DDS useful in the field of chemical industry such as fiber and resin, simply and in high yield by isomerizing 2,4'-DDS to 4,4'-DDS in a suspension of 4,4'-DDS and 2,4-DDS in the presence of an aid catalyst while distilling away a liquid phase. CONSTITUTION:2,4'-Dihydroxydiphenylsulfone (2,4'-DDS for short) in a suspension of 4,4'-dihydroxydiphenylsulfone (4,4'-DDS for short) and 2,4'-DDS in a liquid dispersion medium such as mesitylene is isomerized into 4,4'-DDS in the presence of an acid catalyst (e.g. phenolsulfonic acid) while distilling away a liquid phase at 120-220 deg.C to give the objective substance. 4,4'-DDS is obtained as dry crystal powder not containing a liquid phase component. After the isomerization, separa tion and removal of the solvent and suspension medium are not required. Espe cially in the case of using mesitylene as the liquid dispersion medium, 4,4'-DDS is in light pink, has excellent hue and this method is effective.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing high purity 4,4'-dihydroxydiphenyl sulfone (hereinafter referred to as r4,4'-DDSJ).

Prior art and its problems In recent years, demand for 4.4'-DDS has increased in the fields of chemical industries such as textiles and resins, and moreover, higher purity has been required in each field. ing.

As a method for producing 4.4'-DDS, phenol and a sulfonating agent or phenolsulfonic acid are subjected to a dehydration reaction in the presence of a solvent such as dichlorobenzene that dissolves the above-mentioned raw materials and the produced 4.4'-DDS. method is known. However, when using this method, the target object is 4.4
'-DDS has an isomerization equilibrium with the isomer 2,4'-dihydroxydiphenylsulfone (hereinafter referred to as 2,4'-DDSJ), which is a by-product, in the solution state, so the resulting crude product contains 20 to 30% by weight. % of 2,4'-DD
S is contained as an impurity.

Therefore, the present inventor first dehydrated phenol and sulfuric acid in the presence of a solvent as a method for obtaining 4.4'-DDS with high purity and high yield, and then gradually removed the solvent from the reaction solution. While removing the by-product 2,4'-DDS, 4.4'-
By isomerizing to DDS, highly pure 4.4'-
Method for manufacturing DDS (Japanese Patent Publication No. 1989-8972)
proposed.

This method takes advantage of the difference in solubility in solvents between 4.4'-DDS and 2.4'-DDS, gradually removes the solvent, and precipitates only 4.4'-DDS outside the prefecture. By shifting the isomerization equilibrium in
Proceed with isomerization of DS to 4.4'-DDS to 4.4'
- This aims to improve the purity and yield of DDS. However, according to the above method, the reaction product solidifies from a molten state as the solvent is removed, resulting in a viscous solid with no fluidity, so a special stirring device is required for production.
It is difficult to increase the size of the device.

JP-A-64-9970 discloses that phenol and sulfuric acid are subjected to a dehydration reaction in the presence of an aliphatic hydrocarbon suspending agent and an azeotropic agent, and then the reaction mixture is heated together with the suspending agent to perform an isomerization reaction. A method to complete the process has been proposed. However, in the above method, unless the isomerization is carried out under well-controlled temperature conditions at high temperatures and for a long time, 2.4' = DD
It is not possible to substantially complete the isomerization of S and obtain 4,4'-DDS with high purity. Furthermore, since the isomerization is carried out in the presence of a suspending agent, the capacity of the apparatus becomes large, which inevitably leads to thermal uneconomical costs.

Means for Solving the Problems The present invention was made to solve the above problems and to obtain 4,4'-DDS with high purity and high yield by a simpler method than conventional methods. be.

That is, the present invention provides 4,4'-DDS and 2,4'-DDS.
A suspension containing 2.4'-D in a liquid dispersion medium is heated in the presence of an acid catalyst to distill off the liquid phase.
Proceeding the isomerization reaction of DS to 4.4'-DDS,
High purity 4.4 with essentially all of the liquid phase removed
'-High purity 4.4 characterized by obtaining DDS
' - This relates to a method for manufacturing DDS.

According to the research of the present inventor, 4.4'-DDS and 2.4
-DDS in a liquid dispersion medium in a suspended state, when the liquid phase is gradually distilled off in the presence of an acid catalyst to remove the solid phase, the solid phase is removed by distillation. 2.4' in the process
It has been found that the isomerization reaction of -DDS to 4,4'-DDS progresses favorably and that extremely high purity 4,4'-DDS can be efficiently obtained as a solid. Since the isomerization of the present invention is initially carried out in a suspension, it can be easily stirred and progressed, and even when it finally becomes a solid phase, the
- The purity of DDS is extremely high, so it can be easily handled without problems of viscosity. Further, according to research conducted by the present inventors, a new fact has been discovered that even if the liquid phase is distilled off before the isomerization reaction is completed and heating is continued as a solid phase, the isomerization reaction proceeds in the same way. In this case, since the solid phase does not become viscous, stirring is easy and there is no operational inconvenience. In particular, when mesitylene is used as a liquid dispersion medium, the solid phase remains smooth after the liquid phase is distilled off, making it extremely easy to handle, and stirring isomerization in the solid phase can be carried out using ordinary stirring equipment. It can be easily done using

The suspension in the present invention includes 4,4'-DDS
As long as 2.4'-DDS and 2.4'-DDS are present in a suspended state in a liquid dispersion medium, the method can be applied regardless of the manufacturing method. For example, it is most preferable to use a suspension obtained by dehydrating phenol and a sulfonating agent or phenolsulfonic acid in a liquid dispersion medium that does not dissolve 4,4'-DDS. The above-mentioned suspension contains phenolsulfonic acid, which was produced intermediately during the dehydration reaction or used as a raw material, and acts as an acid catalyst for the isomerization reaction, so it can be used as is in the isomerization reaction of the present invention. can.

As the sulfonating agent used in the above dehydration reaction, a wide variety of conventionally known agents can be used, such as concentrated sulfuric acid, sulfuric anhydride, fuming sulfuric acid, chlorosulfonic acid, and the like. The ratio of phenol and sulfonating agent or phenol sulfonic acid to be used is not particularly limited and is appropriately selected from a wide range, but usually both are used in a stoichiometric ratio or close to it, or the former is used in excess of the latter. is preferable.

The above dehydration reaction involves a liquid dispersion medium (
(suspending medium). As a suspending medium, mesitylene described in the invention previously developed by the present inventor and filed as Japanese Patent Application No. 1-239523, or a straight chain or branched aliphatic hydrocarbon described in JP-A-64-9970. and aliphatic halohydrocarbons can be used. When using an aliphatic suspending medium, it is necessary to remove by-product water outside the prefecture using an azeotropic agent as described in the above-mentioned publication. Among these, the method using mesitylene as a suspending medium is most suitable. The amount of the reaction liquid medium to be used is not particularly limited as long as it is sufficient to stir the reaction system and is at least an amount that can be refluxed. Usually, it is used in an amount up to about 5 times the amount of phenol from the viewpoint of economy, but there is no harm in using it in an amount exceeding this amount.

The dehydration reaction may be carried out according to conventional methods. This is usually carried out by separating and removing produced water while stirring and refluxing the reaction medium. As the reaction temperature, an appropriate temperature may be selected as appropriate from the range of usually 120 to 220°C. When the dehydration reaction proceeds while suspending the produced DDS in mesitylene, it is particularly preferable to carry out azeotropic distillation of by-product water together with mesitylene under stirring at a relatively low temperature of 140 to 165°C to separate and remove water. The mesitylene is refluxed.

When the dehydration reaction is carried out in mesitylene, it is easier to stir and produce DD compared to when it is carried out in other suspension media or solvents.
This method is advantageous because S can be stably suspended in the form of fine particles, and there is no need to pay special attention to the rate of temperature increase in the reaction system, making temperature control easy. Furthermore, the purity of 4,4'-DDS in the resulting suspension is also high, making it conveniently applicable to the method of the present invention.

In the above, the reaction solution obtained by performing the dehydration reaction in the suspension medium can be directly subjected to the isomerization of the present invention.

When the above dehydration reaction is carried out in a solvent that dissolves 4.4'-DDS, the product solution is separated into solid and liquid, and then the solid phase is suspended in a liquid dispersion medium that does not dissolve 4.4'-DDS. It may be used in the isomerization of the present invention. As the liquid dispersion medium in this case, the same suspension medium as mentioned above may be used.

In the method of the present invention, a suspension of a DDS mixture is heated in the presence of an acid catalyst to distill off the liquid phase while converting 2,4'-DDS into 4
．． The isomerization reaction to 4'-DDS is allowed to proceed. The suspension obtained by the above dehydration reaction usually contains phenolsulfonic acid, which is produced intermediately during the dehydration reaction or used as a raw material, and this acts as an acid catalyst for the isomerization reaction. It can be used as is in the method.

If the suspension does not contain an acid catalyst or if it is desired to have more acid catalyst present even in a suspension obtained by dehydration, an acid catalyst may be added separately. As the acid catalyst, benzenesulfonic acid, benzenedisulfonic acid, chlorobenzenesulfonic acid, etc. can be used in addition to phenolsulfonic acid. The content of acid catalyst in the suspension is 0.0% relative to the DDS crystal powder mixture. The content is preferably about 5 to 5% by weight.

In the present invention, it is essential to carry out the isomerization reaction while gradually distilling off the liquid phase. The liquid phase may be isomerized while being distilled and recovered while stirring and the degree of vacuum is adjusted, or the liquid phase may be isomerized while being distilled and recovered under normal pressure. The heating temperature may be selected appropriately depending on the degree of reduced pressure, the boiling point of the liquid phase, etc., but is usually 120~
A temperature of about 200°C, preferably 140 to 180°C is suitable. The liquid phase may be distilled off almost simultaneously with the completion of the isomerization reaction, or may be distilled off before the isomerization reaction is completed. In the latter case, since the solid phase is obtained as a smooth crystalline powder, this can be further heated and stirred to a temperature higher than the isomerization temperature to advance the isomerization reaction. The time required for isomerization is usually about 0.5 to 10 hours, and the distillation of the liquid phase can be completed almost at the same time as the isomerization, or it can be completed before that. Although distillation may be completed, the step of isomerizing while distilling off the liquid phase is essential.

Thus, according to the present invention, 4,4'-DDS can be obtained as a smooth crystalline powder containing no liquid phase components with high purity and high yield, and there is no need to separate and remove the solvent or suspending medium after isomerization. do not have. In particular, when mesitylene is used as the liquid dispersion medium, the resulting 4,4'-DDS has a pale pink hue and is more effective.

EXAMPLES Examples will be shown below to further clarify the features of the present invention.

Example 1 To a mixture of 2.02 mol of phenol and 190 mQ of mesitylene was added 1.0 ml of 98% sulfuric acid with stirring. After dropping 0 mol, 20
The mixture was heated in an oil bath at 0°C to raise the temperature.

The reaction solution started boiling around 145°C. The distillate was condensed in a condenser and separated into two phases in a trap. The upper organic phase was continuously returned to the reactor.

Approximately 4 hours after the start of distillation, the temperature of the reaction system reached 165°C, and the amount of water in the lower phase removed by the trap became 38-. After a further 2 hours had passed, there was no substantial change in the temperature or amount of water in the reaction system, confirming that the dehydration reaction was substantially completed.

Next, the obtained suspension was placed in an oil bath fixed at a temperature of 165°C, and the degree of vacuum in the reaction system was adjusted to gradually remove substantially all of the liquid phase over a period of 3 hours. was collected, and the isomerization reaction was completed. The final degree of vacuum was 1QmmHg.

The composition of the thus obtained product was analyzed by high-performance liquid chromatography (HPLC) and found to be 4.4'-DD8 96.2%2.
4'-DD8 1.8% trihydroxytriphenyldisulfone (hereinafter referred to as "tri-form") 2.0%. In addition, the yield with respect to sulfuric acid was 98.1% in total for the above three components, which was 4.4'
The yield of -DDS was 94.4%.

Example 2 A suspension obtained by dehydration reaction in the same manner as in Example 1 was diluted with 1
Substantially all of the liquid phase was recovered at 65° C. over 0.5 hours while controlling the degree of vacuum. Furthermore, the obtained crystal powder was
The isomerization reaction was completed by heating at 5° C. for 3 hours. The composition of the product thus obtained was determined by HPLC to be 4.4'-DD8 97.0%2.
4'-DD8 1.6%
body
1. It was 4%. In addition, the yield with respect to sulfuric acid is 98% in total for the above three components.
．． 2%, and 95.3% for 4.4'-DDS.

Example 3 A suspension obtained by dehydration reaction in the same manner as in Example 1 was diluted with 1
Substantially all of the liquid phase was recovered at 80° C. over a period of 3 hours while controlling the degree of vacuum. The composition of the product thus obtained was determined by HPLC to be 4.4'-DD8 94.7%2.
4'-DD8 2.5%
body
2. It was 8%.

The yield based on sulfuric acid was 97.5% for the three components, and 92.3% for 4.4'-DDS.

Example 4 A suspension was obtained by dehydration reaction in the same manner as in Example 1 except that the amount of phenol was changed to 2.10 mol. Substantially all of the liquid phase was recovered at 165° C. over 3 hours while controlling the degree of vacuum. The composition of the product thus obtained is HP
By LC, weight ratio: 4.4'-DDS 96.
1%2.4'-DDS
2, Q% Tori Body

1. It was 9%. In addition, the yield for sulfuric acid was 96.3% for the three components, and 96.3% for 4.4'-DDS.
It was 2.5%.

Example 5 A suspension was obtained by carrying out a dehydration reaction in the same manner as in Example 1 except that the amount of phenol was changed to 2.20 mol. Substantially all of the liquid phase was recovered at 165° C. over 3 hours while controlling the degree of vacuum. The composition of the product thus obtained is HP
By LC, weight ratio: 4.4'-DDS 96.
0%2.4'-DD8
2.3% bird body
1.
It was 7%. In addition, the yield for sulfuric acid was 95.5% for the three components, and 91.7% for 4.4'-DDS.
Met.

Claims (6)

[Claims] (1) 4,4'-dihydroxydiphenylsulfone and 2
, 4'-dihydroxydiphenylsulfone in suspension in a liquid dispersion medium is heated in the presence of an acid catalyst to distill off the liquid phase while dissolving 2,4'-dihydroxydiphenylsulfone in a liquid dispersion medium. isomerization reaction into 4,4'-dihydroxydiphenylsulfone to finally obtain high purity 4,4'-dihydroxydiphenylsulfone from which substantially all of the liquid phase has been removed. A method for producing high purity 4,4'-dihydroxydiphenyl sulfone. (2) The method according to claim (1), wherein substantially all of the liquid phase is distilled off almost simultaneously with completion of the isomerization reaction. (3) substantially all of the liquid phase is distilled off before the isomerization reaction is completed, and the solid phase containing 4,4'-dihydroxydiphenylsulfone and 2,4'-dihydroxydiphenylsulfone is then further heated. Claims for completing the isomerization reaction (
The method described in 1). (4) The method according to claim (1), wherein the liquid dispersion medium is mesitylene. (5) Generate phenol and sulfonating agent or phenolsulfonic acid in the presence of a liquid dispersion medium. 4,4'-dihydroxydiphenylsulfone is suspended and subjected to a dehydration reaction to form 4,4'-dihydroxydiphenylsulfone and 2 ，
A suspension in which 4'-dihydroxydiphenyl sulfone is suspended in a liquid dispersion medium is obtained, and the suspension is heated to proceed with the isomerization reaction while distilling off the liquid phase. A method for producing high-purity 4,4'-dihydroxydiphenyl sulfone, which comprises obtaining high-purity 4,4'-dihydroxydiphenyl sulfone from which substantially all of the phases have been removed. (6) The method according to claim (5), wherein the liquid dispersion medium is mesitylene.