Process for the cyclic catalytic preparation of 4,4'-dichlorodiphenyl sulfone

Abstract

The application provides a method for preparing 4,4'-dichlorodiphenyl sulfone through circulation catalysis, and relates to the technical field of dichlorodiphenyl sulfone preparation. Chlorobenzene and p-chlorobenzene sulfonyl chloride are reacted in the presence of a catalyst, anhydrous ferric chloride, at a first predetermined temperature to obtain a solution containing 4,4'-dichlorodiphenyl sulfone, and then the solution is cooled and filtered to obtain a 4,4'-dichlorodiphenyl sulfone crude product. The crude product is then subjected to alkaline treatment, liquid separation, concentration crystallization and recrystallization to obtain 4,4'-dichlorodiphenyl sulfone. The purity of the prepared 4,4'-dichlorodiphenyl sulfone reaches more than 99.6%, and the mother liquor obtained through concentration crystallization can be recycled, so that the raw material and the catalyst, anhydrous ferric chloride, can be reused, and waste is avoided.

Description

Technical Field

[0001] This invention belongs to the technical field of p-chlorobenzenesulfonyl chloride preparation methods, specifically relating to a method for preparing 4,4'-dichlorodiphenyl sulfone by cyclic catalysis. Background Technology

[0002] 4,4'-Dichlorodiphenyl sulfone is an important raw material for synthesizing engineering plastics such as polysulfone, polyethersulfone, and polyetheretherketone. It is also a raw material for synthesizing the drug 4,4'-diaminodiphenyl sulfone. With the increasingly widespread application and development of special engineering plastics in high-tech fields such as automobiles, electronics, and aerospace materials, the demand for it is increasing rapidly.

[0003] Currently, the main methods for preparing 4,4'-dichlorodiphenyl sulfone are the chlorosulfonic acid method, the sulfuryl chloride method, and the sulfur trioxide method, such as the publication numbers CN102351760A, CN103601659A, and CN102304072A. In these patents, p-chlorobenzenesulfonyl chloride is first obtained, and then further catalytically converted to obtain 4,4'-dichlorodiphenyl sulfone. Aluminum trichloride, bismuth tris(trifluoromethyl)sulfonate, or antimony pentachloride are used as catalysts. These catalysts are all single-use and are basically equivalence catalysts, resulting in the generation of a large amount of solid waste and wastewater. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing 4,4'-dichlorodiphenyl sulfone by recycling catalysis with minimal solid waste and wastewater.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A method for the cyclic catalytic preparation of 4,4'-dichlorodiphenyl sulfone includes the following steps:

[0007] S1: At a first predetermined temperature, chlorobenzene and p-chlorobenzenesulfonyl chloride react in the presence of anhydrous ferric chloride catalyst. After the reaction is completed, 4,4'-dichlorodiphenyl sulfone solid is precipitated by cooling. The crude 4,4'-dichlorodiphenyl sulfone product is obtained by filtration. The mother liquor obtained by filtration is used for the preparation of the next batch of crude 4,4'-dichlorodiphenyl sulfone product.

[0008] S2: The crude 4,4'-dichlorodiphenyl sulfone is then treated with liquid alkali, separated, concentrated and crystallized, and recrystallized to obtain 4,4'-dichlorodiphenyl sulfone.

[0009] Preferably, the first predetermined temperature is 90℃-130℃.

[0010] Preferably, the molar ratio of p-chlorobenzenesulfonyl chloride to chlorobenzene and anhydrous ferric chloride is 1:1.5-5:0.01-0.2.

[0011] Preferably, when the mother liquor is used to prepare the next batch of crude 4,4'-dichlorodiphenyl sulfone, the amount of anhydrous ferric chloride added is 1 / 5 to 1 / 4 of the initial amount of anhydrous ferric chloride added when preparing the mother liquor.

[0012] Preferably, when the mother liquor is used to prepare the next batch of crude 4,4'-dichlorodiphenyl sulfone, the amount of chlorobenzene added is 1 / 3 to 2 / 3 of the initial amount of chlorobenzene added when preparing the mother liquor.

[0013] Preferably, in step S1, the reaction ends when the residual p-chlorobenzenesulfonyl chloride content in the reaction solution is ≤3%.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] In this invention, chlorobenzene and p-chlorobenzenesulfonyl chloride react in the presence of anhydrous ferric chloride catalyst at a first predetermined temperature. After the reaction is complete, 4,4'-dichlorodiphenyl sulfone solid is precipitated by cooling and filtered to obtain crude 4,4'-dichlorodiphenyl sulfone. The mother liquor obtained by filtration is used to prepare the next batch of crude 4,4'-dichlorodiphenyl sulfone. The crude 4,4'-dichlorodiphenyl sulfone is then treated with liquid alkali, separated, concentrated and crystallized, and recrystallized to obtain 4,4'-dichlorodiphenyl sulfone. Therefore, by recycling the mother liquor, the utilization rate of raw materials is greatly improved, and the yield of 4,4'-dichlorodiphenyl sulfone is increased. Since less catalyst is used and the mother liquor can be recycled, solid waste and wastewater are reduced, which meets the requirements of green production. Attached Figure Description

[0016] Figure 1 This is the gas chromatogram of Example 1.

[0017] Figure 2 Gas chromatography for Example 2 Figure 1 .

[0018] Figure 3 Gas chromatography for Example 2 Figure 2 .

[0019] Figure 4 This is the gas chromatogram of Experiment No. 1 in Example 3.

[0020] Figure 5 This is the gas chromatogram of Experiment No. 2 in Example 3.

[0021] Figure 6 This is the gas chromatogram of experiment number 3 in Example 3.

[0022] Figure 7 This is the gas chromatogram of experiment number 4 in Example 3.

[0023] Figure 8 This is the gas chromatogram of experiment number 5 in Example 3.

[0024] Figure 9 This is the gas chromatogram of experiment number 6 in Example 3.

[0025] Figure 10 This is the gas chromatogram after vacuum distillation in Example 4.

[0026] Figure 11 This is the gas chromatogram of experiment number 7 in Example 4.

[0027] Figure 12 This is the gas chromatogram of experiment number 8 in Example 4.

[0028] Figure 13 This is the gas chromatogram of experiment number 9 in Example 4. Detailed Implementation

[0029] The technical solutions and effects of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] A method for the cyclic catalytic preparation of 4,4'-dichlorodiphenyl sulfone includes the following steps:

[0031] S1: At a first predetermined temperature, chlorobenzene and p-chlorobenzenesulfonyl chloride react in the presence of anhydrous ferric chloride catalyst. After the reaction is completed, 4,4'-dichlorodiphenyl sulfone solid is precipitated by cooling. The crude 4,4'-dichlorodiphenyl sulfone product is obtained by filtration. The mother liquor obtained by filtration is used for the preparation of the next batch of crude 4,4'-dichlorodiphenyl sulfone product.

[0032] S2: The crude 4,4'-dichlorodiphenyl sulfone is then treated with liquid alkali, separated, concentrated and crystallized, and recrystallized to obtain 4,4'-dichlorodiphenyl sulfone.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] In this invention, chlorobenzene and p-chlorobenzenesulfonyl chloride react in the presence of anhydrous ferric chloride catalyst at a first predetermined temperature. After the reaction is complete, 4,4'-dichlorodiphenyl sulfone solid is precipitated by cooling and filtered to obtain crude 4,4'-dichlorodiphenyl sulfone. The mother liquor obtained by filtration is used to prepare the next batch of crude 4,4'-dichlorodiphenyl sulfone. The crude 4,4'-dichlorodiphenyl sulfone is then treated with liquid alkali, separated, concentrated and crystallized, and recrystallized to obtain 4,4'-dichlorodiphenyl sulfone. Therefore, by recycling the mother liquor, the utilization rate of raw materials is greatly improved, and the yield of 4,4'-dichlorodiphenyl sulfone is increased. Since less catalyst is used and the mother liquor can be recycled, solid waste and wastewater are reduced, which meets the requirements of green production.

[0035] Furthermore, the first predetermined temperature is 90℃-130℃.

[0036] Furthermore, the molar ratio of p-chlorobenzenesulfonyl chloride to chlorobenzene and anhydrous ferric chloride is 1:1.5-5:0.01-0.2.

[0037] Furthermore, when the mother liquor is used to prepare the next batch of crude 4,4'-dichlorodiphenyl sulfone, the amount of anhydrous ferric chloride added is 1 / 5 to 1 / 4 of the initial amount of anhydrous ferric chloride added when preparing the mother liquor.

[0038] Furthermore, when the mother liquor is used to prepare the next batch of crude 4,4'-dichlorodiphenyl sulfone, the amount of chlorobenzene added is 1 / 3 to 2 / 3 of the initial amount of chlorobenzene added when preparing the mother liquor.

[0039] Furthermore, in step S1, the reaction is considered complete when the residual p-chlorobenzenesulfonyl chloride content in the reaction solution is ≤3%.

[0040] For ease of understanding, the present invention is further illustrated by the following embodiments:

[0041] Example 1 (Preparation of 4,4'-dichlorodiphenyl sulfone):

[0042] In a three-necked flask equipped with a stirrer, reflux and hydrogen chloride gas absorption device and a thermometer, 4.1 g of anhydrous ferric chloride, 84 g of chlorobenzene, and 52.6 g of p-chlorobenzenesulfonyl chloride prepared in Example 1 were added respectively. The oil bath was gradually heated to the reaction temperature of 110℃-130℃. The reaction was stopped when the residual p-chlorobenzenesulfonyl chloride content in the reaction solution was ≤3% by sampling and testing at regular intervals (GC method). The reaction was cooled to 5℃, and 4,4'-dichlorodiphenyl sulfone crystals precipitated. The crude product was obtained by filtration. 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 preparation of the next batch of products.

[0043] Crude product purification: a) Alkali treatment: The crude product remaining after distillation is ground into fine particles and then treated with hot 10% liquid alkali (50℃, 30min). Chloroform is added to dissolve the product, and the mixture is stirred at 50℃ for 30min. The liquid is separated to obtain the organic layer, and the aqueous layer is discarded. b) Concentration and crystallization: The organic layer is concentrated at 70℃ to remove most of the chloroform. After cooling and crystallization, the crystals are obtained by filtration. The mother liquor is used for the next batch of crude product treatment. c) Recrystallization: The crystals are redissolved in a 50:50 (v / v) chloroform / ethanol mixed solvent. 0.5% activated carbon is added for further decolorization at 50℃. The product is filtered while hot, and the filtrate is cooled to 5℃, centrifuged, and dried to obtain 4,4'-dichlorodiphenyl sulfone crystals. The purity of the product is determined, and the gas chromatogram is shown below. Figure 1 As shown, the purity reaches over 99.5%.

[0044] The ferric chloride catalyst used in this invention requires a small amount and can be reused, making the reaction controllable. Furthermore, because ferric chloride is soluble in chlorobenzene, most of it remains in solution after the catalytic reaction, while the 4,4'-dichlorodiphenyl sulfone produced precipitates as crystals during cooling, with only a small amount of ferric chloride adsorbed on the surface of the crude product. The mother liquor after separation can be recycled for use in the production process. Therefore, most of the ferric chloride catalyst can be reused, reducing catalyst waste, lowering production costs, reducing the generation of organic waste gas and solid waste, and avoiding the single-use of the catalyst.

[0045] Example 2 (4,4'-Dichlorodiphenyl sulfone preparation mother liquor recycling)

[0046] The above mother liquor was recycled 5 times as follows, with the amount of anhydrous ferric chloride added each time being 1 / 4 of the initial amount.

[0047] In a three-necked flask equipped with a stirrer, reflux device, hydrogen chloride gas absorber, and thermometer, the chlorobenzene mother liquor from Example 1, 52.8 g of p-chlorobenzenesulfonyl chloride, 0.8 g of anhydrous ferric chloride, and 30 g of chlorobenzene were added under stirring. The temperature was raised to 110℃-130℃ and maintained for 6 hours. GC analysis showed that the residual p-chlorobenzenesulfonyl chloride was ≤3%. The heating was stopped, and the temperature was then lowered to 5℃, precipitating 4,4'-dichlorodiphenyl sulfone crystals. The crude product was obtained by filtration. GC analysis showed that the spectra for experiments 2 and 4 were as follows. Figure 2 , 3 As shown in Table 1:

[0048] Table 1

[0049]

[0050] The results above show that, under the same reaction time and temperature conditions, the yield of 4,4'-dichlorodiphenyl sulfone is close to 100%. After being reused 5 times, the content of 4,4'-dichlorodiphenyl sulfone in the crude product is high. Furthermore, the recycling of the mother liquor reduces the waste of raw materials and the other three wastes generated by the treatment of raw material residues. The catalytic preparation process has the least environmental impact and high conversion efficiency, making it suitable for industrial production.

[0051] In step S1, the raw material p-chlorobenzenesulfonyl chloride is prepared through the following steps:

[0052] Step 1: Chlorobenzene and chlorosulfonic acid react at a second predetermined temperature for a first predetermined time to obtain intermediate 1;

[0053] Step 2: Intermediate 1 is reacted with thionyl chloride at a third predetermined temperature for a second predetermined time to obtain a mixed solution containing p-chlorobenzenesulfonyl chloride. The mixed solution containing p-chlorobenzenesulfonyl chloride is then extracted, hydrolyzed, separated, washed, distilled, and recrystallized to obtain p-chlorobenzenesulfonyl chloride.

[0054] Intermediate 1 is obtained by reacting at a second predetermined temperature for a predetermined time. Then, intermediate 1 generates gas under the catalysis of thionyl chloride. After the gas is released, it promotes the reaction between intermediate 1 and chlorobenzene in the forward direction, so that the utilization rate of chlorobenzene reaches more than 90% and the product purity reaches 99%.

[0055] Furthermore, in step one, the chlorosulfonic acid is added dropwise to the chlorobenzene, resulting in a high yield of chlorobenzenesulfonyl chloride and the generation of a small amount of the byproduct 4,4'-dichlorodiphenyl sulfone.

[0056] Furthermore, in step one, the chlorobenzene is added dropwise to the chlorosulfonic acid, resulting in a high yield of intermediate 1 and thus a high yield of p-chlorobenzenesulfonyl chloride.

[0057] Furthermore, the second predetermined temperature is 5℃-45℃, preferably 30℃-35℃, and the first predetermined time is 1h-2h. The formation of intermediate 1 is an exothermic reaction. Under low temperature conditions, the para position is positioned to inhibit the formation of ortho-products, thereby reducing the formation of ortho-byproducts. The third predetermined temperature is 45℃-65℃, preferably 50℃-55℃, and the second predetermined time is 1h-5h, preferably 2.5h-3.5h, so that intermediate 1 reacts with chlorobenzene to form p-chlorobenzenesulfonyl chloride.

[0058] Furthermore, the molar ratio of thionyl chloride to chlorobenzene is 1:2-5. When intermediate 1 and chlorosulfonic acid are not added, the reaction reaches equilibrium. When thionyl chloride is added, its activity is stronger than that of chlorosulfonic acid, thus breaking the equilibrium. With the participation of thionyl chloride, thionyl chloride reacts with intermediate 1 to generate p-chlorobenzenesulfonyl chloride and gas. After the gas is released, it promotes the reaction to proceed in the forward direction. Since intermediate 1 will precipitate at low temperature, it will cause pipeline blockage. After the remaining intermediate 1 is reacted by thionyl chloride, the amount of intermediate 1 in the waste acid is reduced, making the waste acid treatment smoother.

[0059] Furthermore, in step two, the thionyl chloride is added after intermediate 1 has reacted at a third predetermined temperature for 0.5-1.5 hours, and after intermediate 1 and chlorosulfonic acid have reached equilibrium.

[0060] Furthermore, the molar ratio of chlorobenzene to chlorosulfonic acid is 1:2-5, preferably 1:2-3.

[0061] Furthermore, in step two, the extraction step involves adding chloroform as an extractant to a mixed solution containing p-chlorobenzenesulfonyl chloride, and performing extraction to obtain an extract.

[0062] Furthermore, in step two, the hydrolysis specifically involves adding hydrochloric acid to the extract to hydrolyze excess chlorosulfonic acid. The hydrochloric acid is 30% hydrochloric acid. The water in the hydrochloric acid reacts with the unreacted chlorosulfonic acid to produce hydrogen chloride and sulfuric acid. The reaction is exothermic. To prevent localized exothermic reactions that could lead to the hydrolysis of p-chlorobenzenesulfonyl chloride to produce intermediate 1, the generated hydrogen chloride gas carries away the heat of the reaction, thus ensuring that the yield of p-chlorobenzenesulfonyl chloride is not affected.

[0063] Example 3 (p-chlorobenzenesulfonyl chloride):

[0064] In a four-necked flask equipped with a stirrer, reflux and gas absorption apparatus, and a thermometer, chlorosulfonic acid was added, and 0.5 mol of chlorobenzene was added dropwise through a constant-pressure dropping funnel at 6℃-12℃ over 1 hour. After the addition was completed, the temperature was maintained at 6-12℃ for 30 minutes. Then, the temperature was raised to 50-55℃ and maintained for another hour. Next, 0.25 mol of thionyl chloride was added through a dropping funnel over 10 minutes, and the temperature was maintained at 50-55℃ for another 3 hours. After cooling to room temperature, 150 ml of chloroform was added. 35 ml of 30% hydrochloric acid solution was gradually added dropwise through a dropping funnel to decompose excess chlorosulfonic acid. The mixture was separated, and the acid layer was treated as waste acid. The chloroform layer was washed once with distilled water. Most of the chloroform in the washed chloroform layer was removed by atmospheric distillation, and the residual chloroform was removed by vacuum distillation using a water pump to obtain the crude product. A sample was taken for GC analysis.

[0065] Based on the above experimental methods, we explored ways to improve the yield of p-chlorobenzenesulfonyl chloride.

[0066] 1. Three control groups were set up, with 1 mol, 1.25 mol, and 1.5 mol of chlorosulfonic acid added respectively, numbered 1-3. The preparation method was the same as in Example 1 above. GC analysis showed that... Figures 4 to 6 The results are shown in Table 2.

[0067] Table 2

[0068]

[0069] The results above show that when chlorosulfonic acid reacts with chlorobenzene, the higher the molar ratio of chlorosulfonic acid to chlorobenzene, the higher the yield of p-chlorobenzenesulfonyl chloride produced in the crude product. When the molar ratio of chlorosulfonic acid to chlorobenzene is 3:1, the yield of p-chlorobenzenesulfonyl chloride produced in the crude product is 88.44%, while the yields of o-chlorobenzenesulfonyl chloride and 4,4'-dichlorodiphenyl sulfone are only 2.25% and 9.09%, respectively, and the chlorobenzene utilization rate reaches 91.51%.

[0070] When 4,4'-dichlorodiphenyl sulfone is generated from p-chlorobenzenesulfonyl chloride, the optimal molar ratio of chlorosulfonic acid to chlorobenzene is 2.5:1. During the generation of p-chlorobenzenesulfonyl chloride, 16.92% of 4,4'-dichlorodiphenyl sulfone is generated, while the proportions of o-chlorobenzenesulfonyl chloride and 2,4'-dichlorodiphenyl sulfone are very small.

[0071] 2. Set up one control group, numbered 4, at a predetermined temperature of 30℃-35℃ (the temperature at which chlorobenzene is added). The other steps are the same as in section 2. GC analysis was performed, and... Figure 7 As shown in Table 3, the results are as follows.

[0072] Table 3

[0073]

[0074] The results above show that when chlorosulfonic acid reacts with chlorobenzene, the content of p-chlorobenzenesulfonyl chloride increases significantly when the first predetermined temperature is increased, while the content of 4,4'-dichlorodiphenyl sulfone decreases, which is conducive to the formation of p-chlorobenzenesulfonyl chloride.

[0075] 3. One control group was set up, which used water for hydrolysis in the hydrolysis step, without using 30% hydrochloric acid. This control group was numbered 5, and the other steps were the same as in section 2. GC analysis showed that... Figure 8 As shown in the figure, the results are shown in Table 4.

[0076] Table 4

[0077]

[0078] The results above show that when chlorosulfonic acid reacts with chlorobenzene, the products obtained by hydrolysis using pure water and hydrolysis using 30% hydrochloric acid are almost identical. This indicates that the main function of hydrochloric acid is to remove the heat generated by the reaction by producing hydrogen chloride gas. 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 a solid in a concentrated sulfuric acid solution at low temperature, and this solid is difficult to separate and easily leads to pipeline blockage. Using 30% hydrochloric acid, on the one hand, removes local heat through hydrogen chloride to prevent the dissolution of the generated p-chlorobenzenesulfonyl chloride, and on the other hand, the 30% hydrochloric acid dissolves chlorosulfonic acid, making the pipeline unobstructed during waste acid treatment.

[0079] 4. Set up one control group, without adding thionyl chloride in the reaction, and follow the same steps as in step 2. GC analysis was performed, and the results were as follows: Figure 9 As shown in Table 5, the results are as follows.

[0080] Table 5

[0081]

[0082] The results above show that when the equivalent of chlorosulfonic acid cannot affect the proportion of p-chlorobenzenesulfonyl chloride in the crude product, and when thionyl chloride is not added in the reaction, although the proportion of p-chlorobenzenesulfonyl chloride in the crude product is also high, the utilization rate of chlorobenzene is reduced, which reduces the efficiency of chlorobenzene utilization. Therefore, thionyl chloride can improve the efficiency of chlorobenzene utilization, reduce production costs, and facilitate the formation of 4,4'-dichlorodiphenyl sulfone.

[0083] The crude product was subjected to vacuum distillation, yielding a mixture of p-chlorobenzenesulfonyl chloride and o-chlorobenzenesulfonyl chloride. The distillation residue mainly contained 4,4'-dichlorodiphenyl sulfone. The mixture of p-chlorobenzenesulfonyl chloride and o-chlorobenzenesulfonyl chloride was dissolved in a suitable amount of chloroform at 55°C, and the solution was cooled and crystallized under stirring to obtain a solid. The filtered crystals were analyzed by GC. Figure 10 As shown, the results are as follows: the crystals contain more than 99% p-chlorobenzenesulfonyl chloride, a purity suitable for the synthesis of 4,4'-dichlorodiphenyl sulfone; while the ortho-isomer remains in the mother liquor.

[0084] The purification of 4,4'-dichlorodiphenyl sulfone in the distillation residue was the same as that of the crude product in Example 1.

[0085] Example 4 (p-chlorobenzenesulfonyl chloride):

[0086] 1. In a four-necked flask equipped with a stirrer, reflux and gas absorption apparatus, and a thermometer, add 0.5 mol of chlorobenzene. Add 1.25 mol of chlorosulfonic acid dropwise through a constant-pressure dropping funnel at 6℃-12℃ over 1 hour. After the addition is complete, maintain the temperature at 6℃-12℃ for 30 minutes. Then raise the temperature to 50-55℃ and maintain it for 3 hours. After cooling to room temperature, add 150 ml of chloroform. Gradually add 32 ml of 30% hydrochloric acid solution through a dropping funnel to decompose excess chlorosulfonic acid. Separate the layers; treat the acid layer as waste acid, and wash the chloroform layer once with distilled water. Distill the washed chloroform layer at atmospheric pressure to remove most of the chloroform, then use a water-pumped, reduced-pressure distillation to remove the residual chloroform, obtaining the crude product. Take a sample for GC analysis. Figure 11 As shown in Table 6, Experiment No. 7, the crude product purification steps are the same as in Example 1.

[0087] Table 6

[0088]

[0089] A comparison of Experiments 2 and 7 shows that p-chlorobenzenesulfonyl chloride can be generated regardless of the amount of material added. However, when chlorosulfonic acid is added dropwise to chlorobenzene, the utilization rate of chlorobenzene increases to 96.68%, but the content of p-chlorobenzenesulfonyl chloride in the crude product decreases to 66.71%, and the content of o-chlorobenzenesulfonyl chloride in the crude product is as low as 0.89%. In addition, 32.04% of 4,4'-dichlorodiphenyl sulfone is generated. If 4,4'-dichlorodiphenyl sulfone is prepared directly through the above reaction, adding chlorosulfonic acid dropwise to chlorobenzene is beneficial to the formation of 4,4'-dichlorodiphenyl sulfone.

[0090] 2. Set up one control group, numbered 8, at a predetermined temperature of 30℃-35℃ (the temperature during the addition of chlorosulfonic acid). The other steps are the same as in section 7. GC analysis was performed, and... Figure 12 As shown in the figure, the results are shown in Table 6.

[0091] Table 7

[0092]

[0093] The results above show that increasing the first predetermined temperature can improve the utilization rate of chlorobenzene, thereby reducing production costs.

[0094] 3. Set up one control group, without adding thionyl chloride in the reaction, similar to group 9, with the other steps being the same as in group 7. GC analysis was performed, and the results were as follows: Figure 13 As shown in the figure, the results are presented in the table.

[0095] Table 8

[0096]

[0097] The results above show that thionyl chloride can improve the efficiency of chlorobenzene utilization, thereby reducing production costs.

[0098] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for the cyclic catalytic preparation of 4,4'-dichlorodiphenyl sulfone, characterized in that: Includes the following steps: S1: Chlorobenzene and p-chlorobenzenesulfonyl chloride react in the presence of anhydrous ferric chloride catalyst at 90℃-130℃. After the reaction is completed, 4,4'-dichlorodiphenyl sulfone solid is precipitated by cooling. The crude product of 4,4'-dichlorodiphenyl sulfone is obtained by filtration. The mother liquor obtained by filtration is used for the preparation of the next batch of crude 4,4'-dichlorodiphenyl sulfone. The reaction is considered complete when the residual p-chlorobenzenesulfonyl chloride content in the reaction solution is ≤3%. The molar ratio of p-chlorobenzenesulfonyl chloride to chlorobenzene and anhydrous ferric chloride is 1:1.5-5:0.01-0.

2. When the mother liquor is used to prepare the next batch of crude 4,4'-dichlorodiphenyl sulfone, the amount of anhydrous ferric chloride added is 1 / 5-1 / 4 of the initial amount of anhydrous ferric chloride added when preparing the mother liquor; the amount of chlorobenzene added is 1 / 3-2 / 3 of the initial amount of chlorobenzene added when preparing the mother liquor. S2: The crude 4,4'-dichlorodiphenyl sulfone is then treated with liquid alkali, separated, concentrated and crystallized, and recrystallized to obtain 4,4'-dichlorodiphenyl sulfone.

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