JP2815071B2 - Method for producing dichlorodiphenyl sulfone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing 4,4'-dichlorodiphenyl sulfone, which is useful as a raw material for heat-resistant resins such as polysulfone and polyether sulfone, and as an intermediate for various pharmaceuticals.

2. Description of the Related Art Conventionally, as a method for producing 4,4'-dichlorodiphenylsulfone, 4-chlorobenzenesulfonyl chloride is prepared from 4-chlorobenzenesulfonic acid and thionyl chloride in dimethylformamide. A method of reacting with chlorobenzene by a Friedel-Crafts reaction in the presence of an iron chloride catalyst (Japanese Patent Application Laid-Open No. 52-113942), and the reaction of 4-chlorobenzenesulfonic acid with chlorobenzene in the presence of a dehydrating agent such as phosphorus pentoxide or tungstophosphoric acid. A reaction method (Japanese Patent Publication No. 4324662 / JP-A-63-23854), a condensing agent such as boric acid or trifluoromethanesulfonic acid is added, and 4-chlorobenzenesulfonic acid and chlorobenzene are reacted under high pressure and high temperature. Method (Japanese Patent Laid-Open No. 2-16)
No. 9565), a method of reacting chlorobenzene and chlorosulfonic acid (Japanese Patent Application Laid-Open No. 58-206552), a reaction system in which the reaction temperature is 220 ° C. or higher under pressure without using a dehydrating agent, a solvent, a catalyst or the like. A method of producing 4,4'-dichlorodiphenyl sulfone by reacting 4-chlorobenzenesulfonic acid with chlorobenzene under severe conditions (Japanese Patent Publication No. 55-47443) is known.

[0002] In the above-mentioned various production methods, a reaction between 4-chlorobenzenesulfonic acid and chlorobenzene is often employed. In this case, it is necessary to separate the product 4,4'-dichlorodiphenylsulfone from the reaction mixture. Then, unreacted 4-chlorobenzenesulfonic acid is washed away with a large amount of water, and when there is much unreacted material, 4-chlorobenzenesulfonic acid is recovered from the aqueous solution and reused in the reaction with chlorobenzene. However, recovery using a large amount of water is not economical.
No. 0672 discloses a method using 4-chlorobenzenesulfonic acid with less than an equivalent amount of limited water.
A method for recovering chlorobenzenesulfonic acid has been proposed. In the method for separating 4,4'-dichlorodiphenylsulfone using a large amount of water, it is costly to recover 4-chlorobenzenesulfonic acid, which has been dehydrated to a certain extent, from a large amount of water. However, there is a problem that a small amount of 4-chlorobenzenesulfonic acid is mixed in the separated product 4,4'-dichlorodiphenylsulfone, and the high purity 4,4 '
-Preparation of dichlorodiphenyl sulfone requires a complicated process.

[0003]

The present invention provides a high-purity 4,4'-dichlorodiphenyl sulfone from a reaction mixture of 4-chlorobenzenesulfonic acid and chlorobenzene by a simple separation process. Provide a way to The present invention reacts 4-chlorobenzenesulfonic acid with chlorobenzene, and the reaction product 4,4
From the reaction mixture containing 4'-dichlorodiphenyl sulfone and unreacted 4-chlorobenzene sulfonic acid, 4
-When chlorobenzenesulfonic acid is recovered and reused in the reaction, (a) alcohol is added to the reaction mixture to precipitate 4,4'-dichlorodiphenylsulfone as crystals, and (b) 4,4'- The alcohol is distilled off from the residual solution after dichlorodiphenylsulfone is separated and removed, and (c) after removing the alcohol, the residue mainly consisting of 4-chlorobenzenesulfonic acid is reused in the reaction with chlorobenzene. And 4,4'-dichlorodiphenyl sulfone.

[0004] 4-Chlorobenzenesulfonic acid as a raw material used in the present invention is produced by a reaction between a conventionally well-known chlorobenzene and a sulfonating agent, such as fuming sulfuric acid, sulfuric anhydride, concentrated sulfuric acid, or chlorosulfonic acid. be able to. The molar ratio of chlorobenzene to the sulfonating agent is 10/1 to 1/1, more preferably 5/1 to 2
/ 1, the reaction temperature is 70 to 150 ° C, and the reaction time is 0.5 to 10 hours. Following the sulfonation of chlorobenzene, the reaction conditions were changed in the same reactor where a small amount of unreacted sulfonating agent remained,
The reaction between 4-chlorobenzenesulfonic acid of the present invention and chlorobenzene can be carried out.

In the present invention, the reaction of 4-chlorobenzenesulfonic acid with chlorobenzene using a known condensing agent or catalyst, or 4-chlorobenzenesulfonic acid under pressure and high temperature without using a condensing agent or a catalyst. And chlorobenzene, the reaction product 4,4 '
A reaction mixture containing -dichlorodiphenylsulfone and unreacted 4-chlorobenzenesulfonic acid can also be obtained.

In the present invention, the reaction between 4-chlorobenzenesulfonic acid and chlorobenzene is carried out under atmospheric pressure and without adding any condensing agent or the like to the reaction mixture.
Heating can be performed while stirring for 20 hours.
In this case, the heating temperature depends on the proportion of chlorobenzene in the reaction mixture containing chlorobenzene, 4-chlorobenzenesulfonic acid, and the reaction product 4,4′-dichlorodiphenylsulfone. The temperature is 130 to 250 ° C, and a particularly preferred temperature range is 140 to 220 ° C. When the heating temperature is lower than 130 ° C., the reaction rate is extremely slow, and the heating temperature is 25 ° C.
When the temperature is higher than 0 ° C., the amount of by-products increases. The reaction between 4-chlorobenzenesulfonic acid and chlorobenzene produces 4,4'-dichlorodiphenylsulfone and water, and the water is removed from the reaction mixture by azeotropic removal with chlorobenzene as a raw material. In this reaction, in order to efficiently azeotropically remove water with chlorobenzene at atmospheric pressure, chlorobenzene, 4-chlorobenzenesulfonic acid, and 4,4′-dichlorodiphenylsulfone, which is a reaction product, are More preferably, chlorobenzene is maintained at 40% by weight or less, and more preferably 35% by weight or less.
If the amount of chlorobenzene is more than 40% by weight, the reaction temperature cannot be adjusted to a desired temperature, and therefore the reaction rate is extremely slow.

In the present invention, the product 4,4'-
As a reaction system for obtaining a reaction mixture containing dichlorodiphenyl sulfone and unreacted 4-chlorobenzenesulfonic acid, a batch system or a distribution system can be exemplified. In any of the above reaction methods, as a method of separating chlorobenzene from water-containing chlorobenzene removed from the reaction mixture during the reaction from the reaction mixture, after cooling and condensing, separated into two layers of an aqueous layer and chlorobenzene, or
Dehydration with concentrated sulfuric acid to separate the dehydrated chlorobenzene layer. In addition, the separated chlorobenzene layer is further contacted with an inorganic dehydrating agent such as molecular sieves, silica, alumina, calcium chloride, phosphorus pentoxide, magnesium sulfate, and sodium sulfate, and the anhydrous chlorobenzene is supplied as a raw material to the reaction mixture. Is more preferred. In order to continuously supply chlorobenzene to the reaction mixture during the reaction, azeotropically removed water-containing chlorobenzene is passed through a column packed with the inorganic dehydrating agent and dehydrated,
It can be returned directly to the reaction mixture. In any of the above methods, by returning the separated chlorobenzene to the reaction mixture, the raw materials can be supplied and the reaction temperature can be maintained in a desired range.

[0008] In the present invention, 4,
The reaction mixture containing 4'-dichlorodiphenyl sulfone and unreacted 4-chlorobenzene sulfonic acid is added to the first mixture.
, And 4,4'-dichlorodiphenylsulfone is precipitated as crystals. 4,4′-Dichlorodiphenyl sulfone can be directly precipitated as a crystal by adding alcohol to the reaction mixture, but preferably, after addition of the alcohol, the reaction mixture is heated to once form a uniform organic phase, By cooling the organic phase, a crystal of 4,4′-dichlorodiphenylsulfone having high purity can be separated. More preferably, the unreacted chlorobenzene is distilled off before adding the alcohol to the reaction mixture, the alcohol is added, and the mixture is heated to form a uniform organic phase, and then cooled to crystallize 4,4′-dichlorodiphenylsulfone. Things can be separated.

The alcohol which can be used in the present invention includes:
Although there is no particular limitation, those having a relatively low boiling point are preferable,
For example, methanol, ethanol, propanol, butanol and the like can be mentioned. To form a homogeneous organic phase, after the alcohol has been added to the reaction mixture, the mixture is heated at a temperature up to 300 ° C., preferably at the reflux temperature.
The amount of the alcohol used is 100 to 2000 parts, preferably 200 to 600 parts, per 100 parts of the reaction mixture.
Department. If the amount of the alcohol is less than 100 parts, a uniform organic phase cannot be formed, and the product 4,
The purity of 4'-dichlorodiphenyl sulfone decreases.
On the other hand, if the amount of the alcohol used exceeds 2000 parts, the crystallization of the product becomes insufficient, and the yield of the product decreases.

[0010] Next, the alcohol is distilled off from the remaining solution after separating the precipitate 4,4'-dichlorodiphenylsulfone. The residue after removing the alcohol contains 4-chlorobenzenesulfonic acid as a main component and a small amount of 4,
4'-dichlorodiphenylsulfone, and also chlorobenzene when chlorobenzene is not distilled off before addition of alcohol. This residue, together with the newly required amount of chlorobenzene, is reused in the reaction of chlorobenzene with 4-chlorobenzenesulfonic acid. It is not preferable from the viewpoint of the reaction that alcohol remains in the residue, but by using an alcohol having a relatively low boiling point, the alcohol can be sufficiently removed from the residue at low cost.

[0011]

In the present invention, an alcohol is used in place of water, which has been often used in the prior art, to obtain a high-purity 4,4'-diamine from a reaction mixture of 4,4'-dichlorodiphenylsulfone and 4-chlorobenzenesulfonic acid. Dichlorodiphenyl sulfone is separated, 4-chlorobenzenesulfonic acid is easily recovered from the residual liquid, and the operation of using it again in the reaction is repeated many times, whereby economically superior 4,4'-dichlorodiphenyl sulfone is obtained. Provide manufacturing method

[0012]

Examples of the present invention will be described below. Example 1 225.1 g (2.0 M) of chlorobenzene and 91.6 g (1.0 M) of 30% fuming sulfuric acid were charged into a 500 ml flask, and the reaction was continued at 135 ° C. for 4 hours.
1 product water was separated from the reaction mixture. 160 g of 4-chlorobenzenesulfonic acid generated in the flask, 6 g of remaining sulfuric acid, and 132 g of unreacted chlorobenzene
Met. Further, about 88.9 g of chlorobenzene was distilled from the reaction mixture together with by-product water, and the temperature of the reaction mixture was set to 200 ° C. During the reaction, hydrous chlorobenzene is
After condensing through a Liebig condenser, water was separated by a water separator, and the lower chlorobenzene was returned to the reaction vessel through a column packed with molecular sieves (3A). As the reaction proceeds, the temperature of the reaction mixture is increased to about 200
Chlorobenzene was successively added to the reaction mixture so as to be able to be maintained at ° C., and at the same time, chlorobenzene was gradually distilled off together with water. The reaction between chlorobenzene and 4-chlorobenzenesulfonic acid was carried out for 10 hours while maintaining the reaction temperature at about 200 ° C. During this time, 31.3 chlorobenzene
g was consumed in the reaction.

[0013] 3 residual chlorobenzene from the reaction mixture
8.8 g was removed by distillation under reduced pressure, 350 g of ethanol was added, and the mixture was heated near the boiling point of ethanol to obtain a homogeneous solution.
When this solution was cooled to room temperature, white needle-like crystals precipitated. The yield of precipitated crystals after filtration and drying was 77.3.
g (0.27 mol), and 4,4′-dichlorodiphenyl sulfone having a purity of 99.5% or more was obtained. Ethanol was distilled off from the residual solution after filtering and separating the crystals, and a residue comprising 85.3% by weight of 4-chlorobenzenesulfonic acid and 14.4% by weight of 4,4'-dichlorodiphenylsulfone. 6 g were obtained.

This residue and fresh chlorobenzene
7 g were mixed, and the condensation reaction was performed again at 200 ° C. for 10 hours. In the second reaction, chlorobenzene 20.3
g was consumed in the reaction, and after the reaction was completed, 39.8 g of chlorobenzene was recovered from the reaction mixture. By the same operation as described above, 67.0 g (0.23 mol) of 4,4′-dichlorodiphenyl sulfone having a purity of 99.5% or more was obtained. The total amount of high-purity 4,4'-dichlorodiphenylsulfone produced in these two reactions was 144.3 g (0.5 mol).
l) and the yield is the chlorobenzene consumed (15
It was 73% on a 4.4 g) basis. The remaining 4,4′-dichlorodiphenyl sulfone in the residual solution was 18.5.
g (0.06 mol).
The overall yield of 4'-dichlorodiphenyl sulfone was 83% based on chlorobenzene consumed.

Claims (1)

(57) [Claims] 1. A reaction between 4-chlorobenzenesulfonic acid and chlorobenzene, and the reaction product 4,4
From the reaction mixture containing 4'-dichlorodiphenyl sulfone and unreacted 4-chlorobenzene sulfonic acid, 4
-When chlorobenzenesulfonic acid is recovered and reused in the reaction, (a) alcohol is added to the reaction mixture to precipitate 4,4'-dichlorodiphenylsulfone as crystals, and (b) 4,4'- The alcohol is distilled off from the residual solution after dichlorodiphenylsulfone is separated and removed, and (c) after removing the alcohol, the residue mainly consisting of 4-chlorobenzenesulfonic acid is reused in the reaction with chlorobenzene. A method for producing 4,4′-dichlorodiphenyl sulfone.