CN116768768A - Method for preparing 4,4' -dichlorodiphenyl sulfone by cyclic catalysis - Google Patents

Abstract

The invention provides a method for preparing 4,4' -dichlorodiphenyl sulfone by circulating catalysis, which relates to the technical field of dichlorodiphenyl sulfone preparation, chlorobenzene and p-chlorobenzenesulfonyl chloride react in the presence of anhydrous ferric trichloride serving as a catalyst at a first preset temperature to obtain a solution containing 4,4' -dichlorodiphenyl sulfone, the solution is cooled and filtered to obtain a crude product of 4,4' -dichlorodiphenyl sulfone, then the crude product is subjected to alkali treatment, liquid separation, concentrated crystallization and recrystallization to obtain the 4,4' -dichlorodiphenyl sulfone, the purity of the prepared 4,4' -dichlorodiphenyl sulfone reaches more than 99.6%, and mother liquor of the concentrated crystallization can be recycled, so that raw materials and the anhydrous ferric trichloride serving as the catalyst can be reused without waste.

Description

Method for preparing 4,4’-dichlorodiphenylsulfone through cyclic catalysis

Technical field

The invention belongs to the technical field of preparation methods for p-chlorobenzenesulfonyl chloride, and specifically relates to a method for cyclic catalytic preparation of 4,4'-dichlorodiphenyl sulfone.

Background technique

4,4'-Dichlorodiphenylsulfone is an important raw material for the synthesis of engineering plastics polysulfone, polyethersulfone, and polyetheretherketone. It is also a raw material for the synthesis of the drug 4,4'-diaminodiphenylsulfone. With the development of special engineering Plastics are increasingly widely used and developed in high-tech fields such as automobiles, electronic appliances, and aerospace materials, and the demand for them is increasing rapidly.

At present, the chlorosulfonic acid method, sulfuryl chloride and sulfur trioxide method are mainly used to prepare 4,4'-dichlorodiphenyl sulfone. For example, the publication numbers are CN102351760A, CN103601659A, and CN102304072A. In this patent, p-chlorobenzenesulfonyl chloride is first obtained, and then Further catalytic conversion yields 4,4'-dichlorodiphenylsulfone, using aluminum trichloride or bismuth tris(trifluoromethyl)sulfonate or antimony pentachloride as catalysts. These catalysts are disposable and basically Equivalent catalyst, resulting in a large amount of solid waste and wastewater.

Contents of the invention

In view of this, the present invention provides a cyclic catalytic preparation method for 4,4’-dichlorodiphenyl sulfone with less solid waste and waste water.

The technical solutions adopted by the present invention to solve the technical problems are:

A method for preparing 4,4’-dichlorodiphenylsulfone through cyclic catalysis, comprising the following steps:

S1: At the first predetermined temperature, chlorobenzene and p-chlorobenzenesulfonyl chloride react in the presence of anhydrous ferric chloride as the catalyst. After the reaction is completed, cool and precipitate 4,4'-dichlorodiphenylsulfone solid, and pump out Filter to obtain crude 4,4'-dichlorodiphenylsulfone; the mother liquor obtained by suction filtration is used for the preparation of the next batch of crude 4,4'-dichlorodiphenylsulfone;

S2: The crude 4,4’-dichlorodiphenylsulfone is then treated with liquid alkali, liquid separated, concentrated and crystallized, and recrystallized to obtain 4,4’-dichlorodiphenylsulfone.

Preferably, the first predetermined temperature is 90°C-130°C.

Preferably, the molar ratio of the p-chlorobenzenesulfonyl chloride to the chlorobenzene and anhydrous ferric chloride is 1:1.5-5:0.01-0.2.

Preferably, when the mother liquor is used for the preparation of the next batch of crude 4,4'-dichlorodiphenylsulfone, the additional amount of anhydrous ferric chloride is 1/1 of the initial addition amount of anhydrous ferric chloride when preparing the mother liquor. 5-1/4.

Preferably, when the mother liquor is used for the preparation of the next batch of crude 4,4'-dichlorodiphenylsulfone, the additional amount of chlorobenzene is 1/3-2/3 of the initial added amount of chlorobenzene when preparing the mother liquor.

Preferably, in step S1, the reaction is completed when the residual p-chlorobenzenesulfonyl chloride content in the reaction solution is ≤3%.

Compared with the prior art, the beneficial effects of the present invention are:

In the present invention, chlorobenzene and p-chlorobenzene sulfonyl chloride react in the presence of anhydrous ferric chloride as a catalyst at a first predetermined temperature. After the reaction is completed, 4,4'-dichlorodiphenyl sulfone solid is precipitated by cooling, and is pumped Filter to obtain 4,4'-dichlorodiphenyl sulfone crude product; the mother liquor obtained by suction filtration is used for the preparation of the next batch of 4,4'-dichlorodiphenyl sulfone crude product; then 4,4'-dichlorodiphenyl sulfone is After rough treatment with liquid alkali, liquid separation, concentrated crystallization, and recrystallization, 4,4'-dichlorodiphenylsulfone is obtained. Therefore, through the recycling of the mother liquor, the utilization rate of the raw materials is greatly improved, and the product 4,4'-dichlorodiphenylsulfone is The yield of phenyl sulfone is increased. Since less catalyst is used, the mother liquor can be recycled, reducing solid waste and waste water, which meets the requirements of green production.

Description of drawings

Figure 1 is a gas chromatogram of Example 1.

Figure 2 is the first gas chromatogram of Example 2.

Figure 3 is the second gas chromatogram of Example 2.

Figure 4 is a gas chromatogram of Experiment No. 1 of Example 3.

Figure 5 is a gas chromatogram of Experiment No. 2 of Example 3.

Figure 6 is a gas chromatogram of Experiment No. 3 of Example 3.

Figure 7 is a gas chromatogram of Experiment No. 4 of Example 3.

Figure 8 is a gas chromatogram of Experiment No. 5 of Example 3.

Figure 9 is a gas chromatogram of Experiment No. 6 of Example 3.

Figure 10 is a gas chromatogram after vacuum distillation in Example 4.

Figure 11 is a gas chromatogram of Experiment No. 7 of Example 4.

Figure 12 is a gas chromatogram of Experiment No. 8 of Example 4.

Figure 13 is a gas chromatogram of Experiment No. 9 of Example 4.

Detailed ways

The technical solutions and technical effects of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings of the present invention.

A method for preparing 4,4’-dichlorodiphenylsulfone through cyclic catalysis, comprising the following steps:

S1: At the first predetermined temperature, chlorobenzene and p-chlorobenzenesulfonyl chloride react in the presence of anhydrous ferric chloride as the catalyst. After the reaction is completed, cool and precipitate 4,4'-dichlorodiphenylsulfone solid, and pump out Filter to obtain crude 4,4'-dichlorodiphenylsulfone; the mother liquor obtained by suction filtration is used for the preparation of the next batch of crude 4,4'-dichlorodiphenylsulfone;

S2: Then the crude 4,4’-dichlorodiphenylsulfone is treated with liquid alkali, liquid separated, concentrated and crystallized, and recrystallized to obtain 4,4’-dichlorodiphenylsulfone.

Compared with the prior art, the beneficial effects of the present invention are:

In the present invention, chlorobenzene and p-chlorobenzene sulfonyl chloride react in the presence of anhydrous ferric chloride as a catalyst at a first predetermined temperature. After the reaction is completed, 4,4'-dichlorodiphenyl sulfone solid is precipitated by cooling, and is pumped Filter to obtain 4,4'-dichlorodiphenyl sulfone crude product; the mother liquor obtained by suction filtration is used for the preparation of the next batch of 4,4'-dichlorodiphenyl sulfone crude product; then 4,4'-dichlorodiphenyl sulfone is After rough treatment with liquid alkali, liquid separation, concentrated crystallization, and recrystallization, 4,4'-dichlorodiphenylsulfone is obtained. Therefore, through the recycling of the mother liquor, the utilization rate of the raw materials is greatly improved, and the product 4,4'-dichlorodiphenylsulfone is The yield of phenyl sulfone is increased. Since less catalyst is used, the mother liquor can be recycled, reducing solid waste and waste water, which meets the requirements of green production.

Further, the first predetermined temperature is 90°C-130°C.

Further, the molar ratio of the p-chlorobenzenesulfonyl chloride to the chlorobenzene and anhydrous ferric chloride is 1:1.5-5:0.01-0.2.

Further, when the mother liquor is used for the preparation of the next batch of crude 4,4'-dichlorodiphenylsulfone, the additional amount of anhydrous ferric chloride is 1/1 of the initial addition amount of anhydrous ferric chloride when preparing the mother liquor. 5-1/4.

Further, when the mother liquor is used to prepare the next batch of crude 4,4’-dichlorodiphenylsulfone, the additional amount of chlorobenzene is 1/3-2/3 of the initial added amount of chlorobenzene when preparing the mother liquor.

Further, in step S1, the reaction is completed when the residual p-chlorobenzenesulfonyl chloride content in the reaction solution is ≤3%.

In order to facilitate understanding, the present invention is further illustrated by the following examples:

Example 1 (Preparation of 4,4’-dichlorodiphenylsulfone):

In a three-necked bottle equipped with a stirrer, reflux and hydrogen chloride gas absorption device and thermometer, add 4.1g of anhydrous ferric chloride, 84g of chlorobenzene and 52.6g of p-chlorobenzenesulfonyl chloride prepared in Example 1; oil bath Gradually raise the temperature to the reaction temperature of 110°C-130°C; regularly take samples and detect (GC method) that the residual p-chlorobenzenesulfonyl chloride content in the reaction solution is ≤3%, stop the reaction; cool to 5°C, and 4,4'-dichlorodichloride will precipitate. Phenyl sulfone crystals were obtained by suction filtration to obtain the crude product; the mother liquor (containing chlorobenzene, most of the catalyst, 4,4'-dichlorodiphenyl sulfone dissolved in chlorobenzene and unreacted p-chlorobenzenesulfonyl chloride) was used for the next batch Product preparation.

Purification of crude product: a) Alkali treatment: Grind the residual crude product into fine particles, then transfer to hot 10% liquid alkali treatment (50°C, 30min), add chloroform to dissolve, stir at 50°C for 30min, and separate the liquids to obtain the organic layer. Discard the aqueous layer; b) Concentration and crystallization: After the organic layer is concentrated at 70°C to remove most of the chloroform, it is cooled and crystallized, and the crystals are obtained by suction filtration. The mother liquor is used for the next batch of crude products; c) Recrystallization: re-dissolve the crystals in Add 0.5% activated carbon to 50:50 (v/v) chloroform/ethanol mixed solvent at 50°C to further decolorize, filter while hot, cool the filtrate to 5°C, centrifuge and dry to obtain crystalline 4,4'-dichlorobiphenyl Sulfone, test the purity of the product, the gas chromatogram is shown in Figure 1, the purity reaches more than 99.5%.

The catalyst ferric chloride used in the invention has a small dosage and can be used repeatedly, making the reaction controllable. And since ferric chloride is soluble in chlorobenzene, most of the ferric chloride remains in the solution after the catalytic reaction is completed. The 4,4'-dichlorodiphenyl sulfone generated by the reaction precipitates crystals during the cooling process, and only A small amount of ferric chloride is adsorbed on the surface of the crude product; the separated mother liquor can continue to be recycled for use in the production process. Therefore, most ferric chloride catalysts can be reused, reducing catalyst waste, lowering production costs, reducing the generation of organic waste gas and solid waste, and avoiding the one-time use of catalysts.

Example 2 (4,4’-dichlorodiphenylsulfone preparation mother liquor recycling)

The above mother liquor is recycled 5 times as follows, and the amount of anhydrous ferric chloride added each time is 1/4 of the initial amount.

In a three-necked bottle equipped with a stirrer, reflux device, hydrogen chloride gas absorption device and thermometer, add the chlorobenzene mother liquor of Experiment 3, 52.8g p-chlorobenzenesulfonyl chloride, 0.8g anhydrous ferric chloride and 30g chlorobenzene; raise the temperature to the reaction temperature of 110°C-130°C, and keep the reaction for 6 hours; analyze the residual p-chlorobenzenesulfonyl chloride in the reaction by GC ≤ 3%, stop the heat preservation, and then lower the temperature to 5°C to precipitate 4,4'-dichloride Diphenyl sulfone crystals were filtered to obtain crude products. After GC analysis, the spectra of experiment times 2 and 4 are shown in Figures 2 and 3, and the results are shown in Table 1:

Table 1

It can be seen from the above results that when the reaction time and temperature conditions are consistent, the yield of 4,4'-dichlorodiphenyl sulfone is close to 100%, and after repeated use 5 times, 4,4'-dichlorodiphenyl sulfone in the crude product The content of sulfone is high, and the recycling of mother liquor reduces the waste of raw materials and other three waste problems caused by processing raw material residues. The catalytic preparation process has minimal impact on the environment, and the conversion efficiency is high, making it suitable for industrial production.

In the S1 step, the raw material p-chlorobenzenesulfonyl chloride is prepared through the following steps:

Step 1: react chlorobenzene and chlorosulfonic acid at a second predetermined temperature for a first predetermined time to obtain intermediate 1;

Step 2: Under the action of thionyl chloride, intermediate 1 is reacted at a third predetermined temperature for a second predetermined time to obtain a mixed solution containing p-chlorobenzenesulfonyl chloride, and then the mixed solution containing p-chlorobenzenesulfonyl chloride is extracted. , hydrolysis, liquid separation, washing, distillation and recrystallization to obtain p-chlorobenzenesulfonyl chloride.

The intermediate 1 is obtained by reacting at the second predetermined temperature for a predetermined time, and then the intermediate 1 generates gas under the catalytic action of sulfoxide chloride. After the gas is released, the reaction between the intermediate 1 and chlorobenzene is promoted to proceed in the forward direction, so as to The utilization rate of chlorobenzene reaches more than 90%, and the product purity reaches 99%.

Further, in the step one, the chlorosulfonic acid is added dropwise to the chlorobenzene, the yield of p-chlorobenzenesulfonyl chloride is high, and a small amount of by-product 4,4'-dichlorodiphenylsulfone is generated.

Further, in the step one, the chlorobenzene is added dropwise to the chlorosulfonic acid, so that the intermediate 1 is formed at a high rate and the yield of p-chlorobenzenesulfonyl chloride is increased.

Further, the second predetermined temperature is 5°C-45°C, preferably 30°C-35°C, and the first predetermined time is 1h-2h. The generation of intermediate 1 is an exothermic reaction. Under low temperature conditions, The para position is positioned to inhibit the generation of ortho products so that the para position intermediate 1 is generated, thereby reducing the formation of ortho by-products. The third predetermined temperature is 45°C-65°C, preferably 50°C-55°C. , the second predetermined time is 1h-5h, preferably 2.5h-3.5h, so that intermediate 1 reacts with chlorobenzene to generate p-chlorobenzenesulfonyl chloride.

Further, the molar ratio of the thionyl chloride to the chlorobenzene is 1:2-5. When the reaction between intermediate 1 and chlorosulfonic acid does not add thionyl chloride, the reaction reaches equilibrium, and the reaction of the thionyl chloride is added. Sulfone, the activity of the thionyl chloride is stronger than the activity of the chlorosulfonic acid, breaking the balance, and with the participation of the thionyl chloride, the thionyl chloride reacts with the intermediate 1 to generate p-chlorobenzenesulfonyl chloride and gas, After the gas is released, the reaction proceeds in the forward direction. Since intermediate 1 will precipitate at low temperature, causing pipe blockage, after the remaining intermediate 1 is reacted with sulfoxide chloride, the amount of intermediate 1 in the waste acid is reduced, making the waste acid treatment More unobstructed.

Further, in the second step, the thionyl chloride is added after the reaction of Intermediate 1 at the third predetermined temperature for 0.5h-1.5h, and then added after the reaction between Intermediate 1 and chlorosulfonic acid reaches equilibrium.

Further, the molar ratio of chlorobenzene to chlorosulfonic acid is 1:2-5, preferably 1:2-3.

Further, in the second step, the extraction step is to add the extraction agent chloroform to the mixed solution containing p-chlorobenzenesulfonyl chloride, perform extraction, and obtain an extraction liquid.

Further, in step two, the hydrolysis is specifically: adding hydrochloric acid to the extract to hydrolyze excess chlorosulfonic acid, the hydrochloric acid being 30% hydrochloric acid, and the water in the hydrochloric acid reacting with the unreacted chlorosulfonic acid to generate hydrogen chloride and Sulfuric acid, the reaction is exothermic. In order to prevent local exotherm, p-chlorobenzenesulfonyl chloride is hydrolyzed to generate intermediate 1. The generated hydrogen chloride gas takes out the heat of the reaction, so that the yield of p-chlorobenzenesulfonyl chloride is not affected.

Example 3 (p-chlorobenzenesulfonyl chloride):

In a four-necked flask equipped with a stirrer, reflux and gas absorption device, and a thermometer, add chlorosulfonic acid, and add 0.5 mol of chlorobenzene dropwise through a constant pressure dropping funnel at 6°C-12°C; the dropwise addition takes 1 hour. After the end, keep it at 6-12°C for 30 minutes; then raise the temperature to 50-55°C and keep it for another 1 hour; then add 0.25 mol of thionyl chloride through the dropping funnel. After 10 minutes of addition, continue to keep it at 50-55°C for 3 hours; cool to After room temperature, add 150ml of chloroform; gradually add 35ml of 30% hydrochloric acid solution through the dropping funnel to decompose excess chlorosulfonic acid; separate the liquids, treat the acid layer with waste acid, and wash the chloroform layer once with distilled water; the washed chloroform layer is distilled away under normal pressure. Most of the chloroform is then flushed with water and vacuum distilled to remove the remaining chloroform to obtain a crude product, which is sampled for GC analysis.

Based on the above experimental methods, methods to improve the yield of p-chlorobenzenesulfonyl chloride were explored.

1. Set up three control groups, add 1 mol, 1.25 mol, and 1.5 mol of chlorosulfonic acid respectively, numbered 1-3. The other preparation methods are the same as those in Example 1 above. After GC analysis, the results are as shown in Figures 4 to 6. As shown in table 2.

Table 2

Experiment number 1 2 3 Chlorosulfonic acid to chlorobenzene molar ratio 2:1 2.5:1 3:1 Yield g 87.3 92.1 92.7 Chlorobenzene utilization rate/% 88.02 93.31 91.51 Proportion of chlorobenzene in crude product/% 1.63 0.96 0.19 Proportion of p-chlorobenzenesulfonyl chloride in crude product/% 79.47 79.96 88.44 The proportion of o-chlorobenzenesulfonyl chloride in the crude product/% 1.57 2.06 2.25 Proportion of 4,4’-dichlorodiphenylsulfone in the crude product/% 17.13 16.92 9.09 Proportion of 2,4’-dichlorodiphenylsulfone in crude product/% 0.19 0.08 0.02

It can be seen from the above results that when chlorosulfonic acid reacts with chlorobenzene, as the molar ratio of chlorosulfonic acid to chlorobenzene increases, the higher the p-chlorobenzenesulfonyl chloride generated in the crude product, the higher the yield. When chlorosulfonic acid and chlorine When the molar ratio of benzene is 3:1, the p-chlorobenzenesulfonyl chloride generated in the crude product is 88.44%, and o-chlorobenzenesulfonyl chloride and 4,4'-dichlorodiphenyl sulfone are only 2.25% and 9.09%, respectively. The utilization rate of chlorobenzene reaches 91.51%.

If 4,4'-dichlorodiphenyl sulfone is generated from p-chlorobenzenesulfonyl chloride, the molar ratio of chlorosulfonic acid to chlorobenzene is 2.5:1. When generating p-chlorobenzenesulfonyl chloride, it is already 16.92 % of 4,4'-dichlorodiphenyl sulfone is generated, and o-chlorobenzenesulfonyl chloride and 2,4'-dichlorodiphenyl sulfone account for a small proportion.

2. Set up 1 control group. The second predetermined temperature is (temperature when chlorobenzene is dropped) 30°C-35°C, numbered 4. The other steps are the same as numbered 2. Analyze by GC, as shown in Figure 7 , the results are shown in Table 3.

table 3

It can be seen from the above results that when chlorosulfonic acid reacts with chlorobenzene, when the first predetermined temperature increases, the content of p-chlorobenzenesulfonyl chloride increases significantly, and the content of 4,4'-dichlorodiphenyl sulfone decreases, which is beneficial to the reaction of chlorobenzene sulfonyl chloride. Generation of chlorobenzenesulfonyl chloride.

3. Set up 1 control group, use water for hydrolysis in the hydrolysis step, and do not use 30% hydrochloric acid for hydrolysis. It is numbered 5. The other steps are the same as number 2. After GC analysis, as shown in Figure 8, the results are as follows As shown in Table 4.

Table 4

Experiment number 2 5 hydrolysis 30% hydrochloric acid pure water Proportion of chlorobenzene in crude product/% 0.96 0.91 Proportion of p-chlorobenzenesulfonyl chloride in crude product/% 79.96 82.46 The proportion of o-chlorobenzenesulfonyl chloride in the crude product/% 2.06 2.32 Proportion of 4,4’-dichlorodiphenylsulfone in the crude product/% 16.92 14.23 Proportion of 2,4’-dichlorodiphenylsulfone in crude product/% 0.08 0.09 Are there solids in the waste acid treatment? none have

From the above results, it can be seen that when chlorosulfonic acid reacts with chlorobenzene, there is almost no difference between the products obtained by hydrolysis using pure water and hydrolysis using 30% hydrochloric acid; indicating that the main function of hydrochloric acid is to take away the heat generated by the reaction by producing hydrogen chloride gas. , and in the subsequent waste acid treatment process, the waste acid is mainly sulfuric acid (concentration 75-80%) and p-chlorobenzenesulfonic acid. A certain concentration of p-chlorobenzenesulfonic acid can precipitate solids in concentrated sulfuric acid solution at low temperature. The solid is difficult to separate and can easily lead to pipe blockage; on the one hand, using 30% hydrochloric acid takes away local heat through hydrogen chloride to prevent the generated p-chlorobenzenesulfonyl chloride from dissolving; on the other hand, 30% hydrochloric acid dissolves chlorosulfonic acid, making the When treating waste acid, the pipeline should be smooth.

4. Set up 1 control group, without adding thionyl chloride in the reaction, and number 6. The other steps are the same as number 2. After GC analysis, as shown in Figure 9, the results are shown in Table 5.

table 5

Experiment number 2 6 With or without the addition of thionyl chloride have none Yield g 92.1 82.43 Chlorobenzene utilization rate/% 93.31 85.51 Proportion of chlorobenzene in crude product/% 0.96 0.09 Proportion of p-chlorobenzenesulfonyl chloride in crude product/% 79.96 78.58 The proportion of o-chlorobenzenesulfonyl chloride in the crude product/% 2.06 1.19 Proportion of 4,4’-dichlorodiphenylsulfone in the crude product/% 16.92 19.99 Proportion of 2,4’-dichlorodiphenylsulfone in crude product/% 0.08 0.15

It can be seen from the above results that when the equivalent of chlorosulfonic acid cannot affect the proportion of p-chlorobenzenesulfonyl chloride in the crude product, and no thionyl chloride is added in the reaction, although the proportion of p-chlorobenzenesulfonyl chloride in the crude product is also high , but the utilization rate of chlorobenzene decreases, which reduces the use efficiency of chlorobenzene. Therefore, thionyl chloride can improve the use efficiency of chlorobenzene, reduce production costs, and facilitate the generation of 4,4'-dichlorodiphenyl sulfone.

The above crude product is distilled under reduced pressure, and the distillate is a mixture of p-chlorobenzenesulfonyl chloride and o-chlorobenzenesulfonyl chloride; the distillation residue mainly contains 4,4'-dichlorodiphenylsulfone, p-chlorobenzenesulfonyl chloride and o-chlorobenzene Mix and dissolve the sulfonyl chloride mixture with an appropriate amount of chloroform at 55°C, and cool and crystallize under stirring to obtain a solid. The crystals obtained by suction filtration are analyzed by GC, as shown in Figure 10. The results are as follows: the crystal contains more than 99% of p-chlorobenzenesulfonyl chloride. This purity is suitable for the synthesis of 4,4'-dichlorodiphenylsulfone; the ortho-isomer remains in the mother liquor.

The purification of 4,4'-dichlorodiphenylsulfone in the distillation residue is the same as the purification of the crude product in Example 1.

Example 4 (p-chlorobenzenesulfonyl chloride):

1. In a four-necked flask equipped with a stirrer, reflux and gas absorption device, and a thermometer, add 0.5 mol of chlorobenzene, and start adding 1.25 mol of chlorosulfonic acid dropwise through a constant pressure dropping funnel at 6°C-12°C. The addition time is 1 hour. After the dropwise addition, keep it at 6℃-12℃ for 30min. Then raise the temperature to 50-55℃ and keep it for 3h. After cooling to room temperature, add 150ml of chloroform. Gradually add 32ml of 30% hydrochloric acid solution through the dropping funnel to decompose the excess. Chlorosulfonic acid; liquid separation, the acid layer is treated with waste acid, and the chloroform layer is washed once with distilled water; the washed chloroform layer is distilled under normal pressure to remove most of the chloroform, and then the residual chloroform is removed by vacuum distillation with a water pump to obtain a crude product, which is sampled for GC Analysis, as shown in Figure 11, the results are shown in Table 6, experiment number 7, the crude product purification steps are the same as Example 1.

Table 6

Comparing Experiment 2 and Experiment 7, it can be seen that no matter how the material is added, p-chlorobenzene xanthoyl chloride can be generated, but when chlorosulfonic acid is added dropwise to chlorobenzene, the utilization rate of chlorobenzene increases to 96.68%, but the p-chlorobenzene sulfonate in the crude product The content of acid chloride was reduced to 66.71%, and the o-chlorobenzenesulfonyl chloride in the crude product was as low as 0.89%, and 32.04% of 4,4'-dichlorodiphenylsulfone was generated. If 4,4'-dichlorodiphenylsulfone is directly prepared through the above reaction When producing chlorodiphenyl sulfone, adding chlorosulfonic acid dropwise to chlorobenzene is beneficial to the generation of 4,4'-dichlorodiphenyl sulfone.

2. Set up one control group. The first predetermined temperature is (temperature when adding chlorosulfonic acid dropwise) 30°C-35°C. The number is 8. The other steps are the same as number 7. After GC analysis, as shown in Figure 12 shows, and the results are shown in Table 6.

Table 7

It can be seen from the above results that increasing the first predetermined temperature can improve the utilization rate of chlorobenzene and reduce the production cost.

3. Set up a control group, without adding thionyl chloride in the reaction, and the same steps as numbered 9, and other steps as numbered 7. After GC analysis, as shown in Figure 13, the results are shown in the table.

Table 8

Experiment number 7 9 With or without the addition of thionyl chloride have none Yield g 88.6 79.3 Chlorobenzene utilization rate/% 96.68 87.29 Proportion of chlorobenzene in crude product/% 0.11 0.12 Proportion of p-chlorobenzenesulfonyl chloride in crude product/% 66.71 65.12 The proportion of o-chlorobenzenesulfonyl chloride in the crude product/% 0.89 0.33 Proportion of 4,4’-dichlorodiphenylsulfone in the crude product/% 32.04 33.96 Proportion of 2,4’-dichlorodiphenylsulfone in crude product/% 0.24 0.47

It can be seen from the above results that thionyl chloride can improve the use efficiency of chlorobenzene and reduce production costs.

What is disclosed above is only the preferred embodiment of the present invention. Of course, it cannot be used to limit the scope of the present invention. Those of ordinary skill in the art can understand all or part of the processes for implementing the above embodiments and make decisions according to the claims of the present invention. Equivalent changes still fall within the scope of the invention.

Claims (6)

1. A method for preparing 4,4’-dichlorodiphenylsulfone through cyclic catalysis, which is characterized in that: it includes the following steps: S1: At the first predetermined temperature, chlorobenzene and p-chlorobenzenesulfonyl chloride react in the presence of anhydrous ferric chloride as the catalyst. After the reaction is completed, cool and precipitate 4,4'-dichlorodiphenylsulfone solid, and pump out Filter to obtain crude 4,4'-dichlorodiphenylsulfone; the mother liquor obtained by suction filtration is used for the preparation of the next batch of crude 4,4'-dichlorodiphenylsulfone; S2: The crude 4,4’-dichlorodiphenylsulfone is then treated with liquid alkali, liquid separated, concentrated and crystallized, and recrystallized to obtain 4,4’-dichlorodiphenylsulfone. 2. The method for preparing 4,4'-dichlorodiphenylsulfone through cyclic catalysis according to claim 1, characterized in that: the first predetermined temperature is 90°C-130°C. 3. The method for cyclic catalytic preparation of 4,4'-dichlorodiphenyl sulfone as claimed in claim 1, characterized in that: the molar ratio of the p-chlorobenzenesulfonyl chloride to the chlorobenzene and anhydrous ferric chloride It is 1:1.5-5:0.01-0.2. 4. The method for preparing 4,4'-dichlorodiphenyl sulfone by cyclic catalysis as claimed in claim 1, characterized in that: when the mother liquor is used for the preparation of the next batch of 4,4'-dichlorodiphenyl sulfone crude product, The added amount of anhydrous ferric chloride is 1/5-1/4 of the initial added amount of anhydrous ferric chloride when preparing the mother liquor. 5. The method for preparing 4,4'-dichlorodiphenyl sulfone by cyclic catalysis as claimed in claim 4, characterized in that: when the mother liquor is used for the preparation of the next batch of 4,4'-dichlorodiphenyl sulfone crude product, The added amount of chlorobenzene is 1/3-2/3 of the initial added amount of chlorobenzene when preparing the mother liquor. 6. The method for cyclic catalytic preparation of 4,4'-dichlorodiphenyl sulfone as claimed in claim 1, characterized in that: in the step S1, when the reaction is completed: when the residual p-chlorobenzene sulfone in the reaction solution Acid chloride content ≤3%.