JPS6136253A - Production of 4,4'-dihydroxydiphenyl sulfone - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high purity and yield in a short process, by distilling away formed water in an amount within a specific range of the theoretical amount, adding a phenolic compound thereto, and reacting the phenol with sulfuric acid under heating at a specific temperature while distilling away the excess amount of the phenol. CONSTITUTION:Phenol is mixed and thermally reacted with sulfuric acid. In the process, formed water in an amount of 75% or more of the theoretical amount thereof is distilled away, and phenol is added to the reaction mixture. The reaction mixture is heated at 140-200 deg.C while distilling away the excess amount of the phenol to give the aimed 4,4'-dihydroxydiphenyl sulfone. The ratio of 2,4'- dihydroxydiphenyl sulfone in the reaction mixture is reduced, and the ratio of the 4,4'-dihydroxydiphenyl sulfone is increased depending on the reaction conditions. The reason why the reaction is completed in a short time is that the intermolecular isomerization reaction expressed by the reaction formula (rings A-C are separate aromatic rings) between the 2,4'-dihydroxydiphenyl sulfone and the phenol seems likely to occur.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing 4,4'-dihydroxydiphenyl sulfone. More specifically, the present invention aims to produce high-purity P, 4, with a low content of 2,4'-dihydroxydiphenyl sulfone from phenol and sulfuric acid.
The present invention relates to a method for producing '-dihydroxydiphenylsulfone in high yield and in a short reaction time.

Conventional technology 4.4'-Dihydroxydiphenyl sulfone has been widely used as a raw material for plating bath additives, leather tanning agents, dyeing aids, phenolic resin curing accelerators, flame retardants, agricultural chemicals, etc. In addition, in recent years, raw materials for engineering plastics such as polycarbanate, polyester, and Iriethersulfone, color photographic elements,
Raw materials for photographic contrast enhancers, color developers for thermal recording paper,
It came to be used as an additive in vesicular recording materials. In such applications, it is often undesirable for the isomer 2,4'-dihydroxydiphenyl sulfone to coexist, and highly pure 4,4'-
Dihydroxydiphenyl sulfone is required.

When dihydroxydiphenyl sulfone is produced by the reaction of phenol and sulfuric acid, the target 4,4'-
In addition to dihydroxydiphenylsulfone, 2,41-dihydroxynophenylsulfone is inevitably produced as a by-product, and its content often reaches 20 to 30%.

Various methods have been proposed to obtain highly pure 4,4'-dihydroxydiphenyl sulfone from such a mixture. For example, in Japanese Patent Publication No. 38-5274, 2゜4'-
Japanese Patent Publication No. 43-24660 describes a method for dissolving dihydroxydiphenylsulfone, a method for extracting 2,4'-dihydroxydiphenylsulfone from a mixture with O-dichlorobenzene, and Japanese Patent Publication No. 47-43936 describes a method for extracting 2,4'-dihydroxydiphenylsulfone from a mixture. A method for selectively dissolving 2,4'-dihydroxydiphenyl sulfone in
Japanese Patent Publication No. 55-37549 discloses a method of dissolving 2,4'-dihydroxydiphenylsulfone in an aqueous methanol solution, and Japanese Patent Publication No. 57-38766 discloses a method of dissolving 2,4'-dihydroxydiphenylsulfone in a mixed solvent of ethyl acetate and 0-dichlorobenzene. A method for dissolving '-dihydroxydiphenylsulfone is described.

Problems to be Solved by the Invention All of these methods involve separating the latter as a solution from a mixture of 4,4'-dihydroxydiphenylsulfone and 2,4'-dihydroxydiphenylsulfone, so they were used. The yield of 4,4'-dihydroxydiphenylsulfone based on the raw material is low, and a separation operation of 2,4'-dihydroxydiphenylsulfone is necessary.
Moreover, it has the disadvantage that the separated 2,4'-cyhydroxydiphenylsulfone must be appropriately treated.

Furthermore, JP-A-57-77667 describes a method for crystallizing 4,4'-dihydroxydiphenylsulfone as a phenol adduct from an isomer mixture; Since this method separates 2,4'-dihydroxydiphenyl sulfone and 2,4'-dihydroxydiphenyl sulfone, it has the same drawbacks as the above-mentioned methods.

A method has been proposed for isomerizing 2,4'-dihydroxydiphenylsulfone to produce 4,4'-dihydroxydiphenylsulfone. That is, JP-A-50-1164
No. 46 discloses that 4,4'-dihydroxydiphenylsulfone is produced by heating an isomer mixture rich in 2,4'-dihydroxydiphenylsulfone at 140 to 250°C in the presence of sulfuric acid, oleum, or phenolsulfonic acid. A manufacturing method has been proposed, and a method has also been described in which phenol is added in an amount of 2 moles to sulfuric acid or oleum. According to this method, 4.4'-
Although it is possible to increase the yield of dihydroxydiphenylsulfone, it is possible to increase the yield of phenol with sulfuric acid, fuming sulfuric acid or phenolsulfonic acid, separation of 2,4'-dihydroxydiphenylsulfone, and isomerism of 2,4'-dihydroxydiphenylsulfone. Three steps are necessary: conversion.

A method for producing highly pure 4,4'-dihydroxydiphenyl sulfone in high yield in one step has also been proposed.

For example, Japanese Patent Publication No. 55-8972 discloses that phenol and sulfuric acid are reacted in the presence of a solvent, and the solvent is gradually removed from the reaction system to precipitate 4,4'-dihydroxydiphenyl sulfone. A method for isomerizing 2,4'-dihydroxydiphenylsulfone to 4,4'-dihydroxydiphenylsulfone is described, and the solvents used include dichlorobenzene, trichlorobenzene fx, and toca, which are inert under the isomerization reaction conditions. 1-
1-I am. Also, UK patent application number 2,030,566
No. 4,4'-dihydroxydiphenylsulfone 91 using a sulfuric acid catalyst in the presence of o-dichlorobenzene.
%,! :2,4'-dihydroxyzophenyl sulfone 9
An example is shown in which a product containing 98.2% of 4,4'-dihydroxydiphenylsulfone is obtained when a mixture of the following is heated. However, in these methods, in addition to the raw materials such as phenol and sulfuric acid, it is necessary to use a solvent such as dichlorobenzene as the first and third components, which not only complicates the manufacturing process, but also causes problems in the product. This is not preferable since there is a possibility that traces of solvent may remain in the isomerization reaction, and it also has the disadvantage that the isomerization reaction requires a relatively long time.

Alternative Means to Solve the Problems The inventors of the present invention have overcome the above-mentioned drawbacks, and have produced high-purity products in one step by using only phenol and sulfuric acid without using a third component such as a solvent. After studying various methods for producing 4゜4'-dihydroxydiphenylsulfone in high yield and in a short reaction time, we found that phenol was added to the reaction mixture at a specific stage of the reaction between phenol and sulfuric acid, and
The present invention was achieved by discovering that 4,4'-dihydroxydiphenylsulfone can be obtained in a short reaction time, in high purity, and in high yield by proceeding with the reaction while distilling off excess phenol. It is.

That is, in the present invention, phenol and sulfuric acid are mixed and heated to produce dihydroxydiphenyl sulfone, and after more than 75% of the theoretical amount of water produced is distilled off, phenol is added to the reaction mixture. The present invention provides a method for producing 4,4'-dihydroxydiphenyl sulfone, which is characterized in that the reaction is carried out by heating at 140°C or higher and 200°C or lower while distilling off an excess amount of phenol.

According to the method of the present invention, since components other than phenol and sulfuric acid are not used, the manufacturing equipment is simple and the reaction operation is easy.There is also no risk of contamination of solvent components into the product, and the reaction is easy. It has the advantage of being completed in a short time.

The reaction between phenol and sulfuric acid can be carried out by commonly known methods. For example, phenol is charged into a reaction tank, then an equivalent amount of sulfuric acid is added, heated while stirring, and the temperature is gradually increased to allow the reaction to occur while distilling off the produced water. At this time, a small amount of phenol will also be distilled off by azeotropic distillation, so either you can charge a slightly excessive amount of phenol in advance, or you can separate the distilled aqueous phase and phenol phase and send the phenol phase back to the reaction tank. Alternatively, the same amount of phenol as the distilled amount may be newly added to the reaction tank. To accelerate the reaction, the reaction vessel may be slightly reduced in pressure to prevent water from distilling off.

After the reaction has proceeded and more than 75% of the theoretical amount of water produced has been distilled off, phenol is added to the reaction mixture. While the amount of water distilled off is less than the theoretical amount of water produced,
Since a considerable amount of unreacted phenol remains in the reaction mixture, the effect of the present invention cannot be obtained even if phenol is newly added.

Phenol may be added immediately when the amount of water distilled off exceeds the theoretical amount of 75 tons, or it may be added after a larger amount of water has been distilled off. Note that water that was originally present in raw materials, etc. shall be excluded from consideration.

The amount of phenol added is preferably 5 parts by weight or more and less than 100 parts by weight (per 100 parts by weight of the reaction mixture), and 10 parts by weight or more (per 100 parts by weight).
Parts by weight or more and less than 50 parts by weight are more preferred. If the amount of additional phenol added is less than 5 parts by weight per 100 parts by weight of the reaction mixture, the effects of the present invention cannot be obtained. Furthermore, even if the additional amount of phenol is 100 parts by weight or more per 100 parts by weight of the reaction mixture, the effects of the present invention can be obtained, but it takes a long time to distill off the excess amount of phenol, which is not a good idea.

Phenol may be added all at once or may be added in several portions. For example, 30 parts by weight of diphenol per 100 parts by weight of the reaction mixture may be added at once when the distilled water reaches the theoretical amount of 75 parts by weight, or 15 parts by weight of each diphenol per 100 parts by weight of the reaction mixture may be added. The amount of water distilled off is 75% and 85% of the theoretical amount, respectively.
You can also add it when you reach 1 and 95.

The reaction pressure after adding phenol can also be arbitrarily selected. The reaction may be carried out at normal pressure, or may be carried out under reduced pressure to avoid distilling off excess phenol. It is not always necessary to continue distilling off the phenol, but after keeping the pressure under pressure for a certain period of time, the pressure may be reduced to normal pressure or reduced pressure and the phenol may be distilled off.

After 75% or more of the theoretical amount of water produced by the reaction is distilled off, phenol is added to the reaction mixture, and the reaction is heated at 140° C. or higher and 200° C. or lower while distilling off excess phenol. This heating reaction reduces the proportion of 2,4'-citroxydiphenylsulfone and increases the proportion of 4,4'-dihydroxydiphenylsulfone in the reaction mixture.

When the temperature is below 140°C, the proportion of 2-4'-dihydroxydiphenylsulfone hardly decreases. Also,
If the temperature exceeds 200°C, the product will become significantly colored, which is not preferable.

The reason why the reaction is completed in a short time by the method of the present invention is not clear, but it is probably due to the formation of separate aromatic rings between 2,4'-dihydroxyphenylsulfone and phenol. It is assumed that this is due to the occurrence of intermolecular isomerization reactions as shown in

Effects of the Invention By the method of the present invention, a product with high purity of 4,4'-dihydroxyphenylsulfone and low content of 2,4'-dihydroxydiphenylsulfone can be obtained. However, it also contains small amounts of colored impurities and impurities such as trihydroxytriphenyldisulfone. If necessary, these impurities can be removed by recrystallization or activated carbon treatment.

EXAMPLES Hereinafter, the present invention will be explained in detail using examples. In addition, 4.4'
The ratio of -17hydroxydiphenylsulfone to 2°4'-dihydroxydiphenylsulfone was analyzed by liquid chromatography.

Example 1 Phenol 3761/and 98 sulfuric acid 2001 in the reactor
I was charged and reacted by heating at 150°C, and the water contained in the sulfuric acid and the water produced by the reaction were distilled off.

Phenol distilled azeotropically with water was separated into phases and refluxed to the reactor. After 3 hours, precipitation of crystals was observed in the reaction mixture, and the amount of water distilled out, excluding the phenol dissolved therein, reached 58.6.9. This is water in sulfuric acid 4. Subtracting Og gives 75.8% of the theoretical amount of 72.011.
corresponds to After this, the reactor was depressurized and the phenol 4
0I was added, and the mixture was further heated at 150° C. for 0.5 hours to distill off phenol and water, and the amount of distilled water reached 65.4 g. At this time, the ratio of 4,4'-dihydroxydiphenylsulfone to 2,4'-dihydroxydiphenylsulfone in the reaction mixture was 81.8:18.2. Now add 36.9 g of phenol to the reactor and add 1
After heating at 65° C. for 0.5 hours, phenol and water were distilled off, and the amount of water distilled off was 72.5 #. At this time, the ratio of 4,4'-dihydroxydiphenylsulfone and 2'4'-dihydroxydiphenylsulfone in the reaction mixture was 96.5:3.5. Furthermore, phenol 24II was added to the reactor and heated at 185° C. for 1 hour to completely distill off phenol and water. 476
g of dihydroxydiphenyl sulfone was obtained, in which the ratio of 4,4' and 2,4' monomers was 99.6:
It was 0.4.

Comparative Example 1 The same operation as in Example 1 was repeated using 0-dichloropenzene as a substitute for the added phenol. A reactor was charged with 376 g of phenol and 200 I of 98-thiosulfuric acid, and 1
The reaction was carried out by heating at 50° C., and the water contained in the sulfuric acid and the water produced by the reaction were distilled off. The phenol distilled azeotropically with water was separated into phases and refluxed to the reactor. 3
After a period of time, precipitation of crystals was observed in the reaction mixture, and the amount of distilled water reached 59, OII. This is water in sulfuric acid 4
．． If 011 is subtracted, it corresponds to 76.4 yen, which is the theoretical amount of 72.011 yen. Thereafter, the pressure in the reactor was reduced, 40 g of 0-dichlorobenzene was added, and the mixture was further heated at 150° C. for 0.5 hours, resulting in a distilled amount of water reaching 64.919. At this time, the ratio of 4,4'-dihydroxydiphenylsulfone to 2,4'-dihydroxydiphenylsulfone in the reaction mixture was 81.5:18.5. Here, 36 g of 0-dichlorobenzene was added to the reactor, and an additional 165 g of 0-dichlorobenzene was added to the reactor.
When heating was continued for 0.5 hour at ℃, the amount of water distilled off was 71.81.

At this time, 4,4'-dihydroxydiphenylsulfone in the reaction mixture,! :2,4'-dihydroxydiphenylsulfone ratio was 89.8:10.2.

Furthermore, 24 Ji' of 0-dichlorobenzene was added to the reactor and heated at 185°C for 1 hour to completely distill off water and 0-dichlorobenzene. 472 g of dihydroxydiphenyl sulfone was obtained, of which the ratio of 4,4' monomer to 2,4' monomer was 94.3:5.761), 4
The purity of 4-nee dihydroxydiphenyl sulfone was not sufficiently high.

Example 2 376 g of phenol and 200.9 g of 98 sulfuric acid were added to the reactor.
When the mixture was heated and reacted at 160° C. for 4 hours in the same manner as in Example 1, 62.4.17 of water was distilled off. At this time, the ratio of 4,4'-dihydroxydiphenylsulfone to 2,4'-dihydroxydiphenylsulfone in the reaction mixture was 79.5:20.5. Here, 150 g of phenol was added to the reactor, and while controlling the pressure, it was heated to 160°C for 0.5 hours, 170°C for 05 hours, and then heated to 180°C for 0.5 hours.
The mixture was heated at 5° C. for 1 hour to distill off excess phenol and water produced by reaction. 482 g of dihydroxydiphenyl sulfone was obtained, of which 4,4' monomer and 2
．． The ratio of 4′ integral was 99.3:0.7.

Comparative Example 2 Phenol 376.9 and 98 sulfuric acid 200# in the reactor
was charged and reacted by heating at 160°C, and the water contained in the sulfuric acid and the water produced by the reaction were distilled off. Phenol distilled azeotropically with water was separated into phases and refluxed to the reactor. After 4 hours, the amount of water distilled off was 62. ' reached #,
At this time, the ratio of 4,4'-dihydroxydiphenylsulfone to 2,4'-dihydroxydiphenylsulfone in the reaction mixture was 79.6:20.4. Here, 150 g of phenol was added to the reactor, and after initially maintaining a pressurized state, the pressure was slightly reduced and the reactor was heated at 210° C. for 2 hours to distill off the produced water and excess phenol. 472 g of dihydroxydiphenyl sulfone was obtained, of which 4,
The ratio of 4' integral to 2,4' integral was 99.5=1.5. Moreover, this dihydroxydiphenyl sulfone was colored dark brown.

Claims (1)

[Claims] 1. When phenol and sulfuric acid are mixed and heated to produce dihydroxydiphenyl sulfone, after 75% or more of the theoretical amount of water produced is distilled off, phenol is added to the reaction mixture and the excess amount of phenol is distilled off. While leaving 1
A method for producing 4,4'-dihydroxydiphenyl sulfone, which comprises carrying out a heating reaction at 40°C or higher and 200°C or lower.