Improved bisphenol S high-purity synthesis method

Abstract

The invention belongs to the technical field of chemical synthesis, and provides an improved high-purity bisphenol S. The improved high-purity bisphenol S synthesis method comprises the following steps: A, mixing mesitylene, phenol and a catalyst, dropwise adding concentrated sulfuric acid under a stirring condition at 75-85 DEG C according to a molar ratio of sulfuric acid to phenol of 1: (1.9-2.2), then heating to reflux, separating out generated water through a water separator, and collecting the separated water; after reacting for 5-6 hours, cooling and filtering to obtain a first crude product; the catalyst is prepared from 4-fluorobenzene sulfonic acid and 1, 5-naphthalene disulfonic acid in a mass ratio of 5: (3.0-3.1); and B, adding methanol into the first crude product, then adding activated carbon, stirring at 55-60 DEG C for 2-2.5 hours, then filtering while hot, cooling filtrate to 8-10 DEG C, stirring and crystallizing for 3-4 hours, carrying out centrifugal separation to obtain a second crude product, and then recrystallizing and drying to obtain bisphenol S. According to the synthesis method provided by the invention, bisphenol S with high purity and high yield is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis and relates to an improved high-purity synthesis method of bisphenol S. Background Art

[0002] Bisphenol S, also known as 4,4'-dihydroxydiphenyl sulfone, or BPS for short, has a wide range of uses. It can be used as a raw material or intermediate in the production of pesticides and dyes. It can replace bisphenol A, which may affect the human endocrine system, and offers advantages in performance and safety. Furthermore, due to its excellent heat, light, and oxidation resistance, bisphenol S is used as a color fixative, plating bath additive, leather tanning agent, dispersant for high-temperature dyeing with disperse dyes, phenolic resin hardening accelerator, and resin flame retardant.

[0003] Currently, the most mainstream industrial method uses phenol and concentrated sulfuric acid as raw materials and produces bisphenol S through a two-step reaction of sulfonation and condensation. Another method is the hydrolysis of 4,4'-dichlorodiphenyl sulfone: hydrolysis under alkaline conditions produces a sodium salt, which is then acidified to produce bisphenol S. This method has high raw material costs, complex processes, and limited industrial application. Another method is the sulfide oxidation method: using 4,4'-dihydroxydiphenyl sulfide as an intermediate, it is oxidized to sulfone using hydrogen peroxide. However, the preparation of intermediates is difficult and involves hazardous reagents (such as sulfur dioxide), resulting in low safety. Therefore, current methods for the high-purity synthesis of bisphenol S mainly combine improvements in catalysts, refining processes, and high-efficiency reactors to significantly improve purity and yield. In general, in the process of synthesizing bisphenol S, the main way to obtain high-purity bisphenol S is to suppress the content of the by-product isomer 2,4'-dihydroxydiphenyl sulfone. For example, the Chinese patent with publication number CN 102942510 A uses 2,6-naphthalene disulfonic acid as a catalyst; the Chinese patent with publication number CN113480457 A, by adjusting the material ratio and the refining and crystallization condition parameters, obtains a considerable product yield, a content ≥99.5%, and a chroma ≤20.

[0004] However, the current methods make it difficult to increase the yield and purity from 95% upwards, so the synthesis of high-purity bisphenol S has become the current research focus. Summary of the Invention

[0005] The present invention provides an improved high-purity synthesis method of bisphenol S, which obtains bisphenol S with high purity and high yield.

[0006] The technical solution of the present invention is achieved as follows: An improved method for synthesizing high-purity bisphenol S comprises the following steps: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid dropwise under stirring at a temperature of 75-85°C for 2.0-3.0 hours, then raise the temperature to reflux, separate the generated water through a water separator, react for 5-6 hours, cool, and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:1.9-2.2; The catalyst is 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:3.0-3.1; The mass ratio of mesitylene to phenol is 1.0-1.2:1; The amount of catalyst used is 0.6-0.8% of the mass of phenol; B. Add methanol to the first crude product, then add activated carbon, stir at 55-60°C for 2-2.5 hours, then filter while hot, cool the filtrate to 8-10°C, stir and crystallize for 3-4 hours, centrifuge to obtain a second crude product, then recrystallize and dry to obtain bisphenol S.

[0007] Preferably, the reflux temperature is 160-165°C.

[0008] Preferably, in step A, the temperature is cooled to 40-50°C.

[0009] Preferably, in step B, the mass ratio of methanol to the first crude product is 3-5:1.

[0010] Preferably, the amount of activated carbon used is 1% to 2% of the quality of the first crude product.

[0011] Preferably, the stirring rates in step A and step B are both 100-200 rpm.

[0012] Preferably, in step B, the centrifugal speed is 3000-5000 rpm, the centrifugal time is 15-25 min, and the centrifugal temperature is 8-10°C.

[0013] Preferably, the recrystallization uses methanol-water solution to dissolve the second crude product, then heats to 55-60° C. and stirs for 3-4 hours, and cools to 15-20° C. and stirs for crystallization for 2-3 hours.

[0014] Preferably, the initial volume ratio of methanol to water in the methanol aqueous solution is 1:2. After stirring for 1 hour, water is gradually added to a volume ratio of methanol to water of 1:3.

[0015] Preferably, the mass ratio of the methanol aqueous solution to the second crude product is 5-7:1.

[0016] Preferably, the drying step comprises vacuum drying at 55-60° C. for 5-6 hours.

[0017] Preferably, the filtrate is cooled to 8-10° C. in step B by gradient cooling. Preferably, the gradient cooling step comprises cooling to 30-40° C. and keeping warm for 0.5-1 h; then cooling to 20° C. and keeping warm for 0.5-1 h; and finally cooling to 8-10° C. and keeping warm for 1-3 h.

[0018] The beneficial effects of the above technical solution of the present invention are: The present invention can significantly improve the synthesis efficiency and product purity of bisphenol S by precisely controlling the catalyst and ratio and optimizing temperature and solvent management. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0020] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The experimental techniques or test methods involved in the embodiments of the present invention, unless otherwise specified, are conventional methods in the prior art, and their names and / or abbreviations are conventional names in this area, and are very clear and definite in the relevant application fields. Those skilled in the art can understand conventional process steps and apply corresponding equipment according to the names, and implement them according to conventional conditions or conditions recommended by the manufacturer. The various instruments, equipment, raw materials or reagents used in the embodiments of the present invention have no special restrictions on source, are conventional products that can be purchased through regular commercial channels, and can also be prepared according to conventional methods well known to those skilled in the art.

[0021] The molar concentration of concentrated sulfuric acid in the following examples and comparative examples is 18.4 mol / L.

[0022] Example 1 An improved method for synthesizing high-purity bisphenol S comprises the following steps: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid dropwise (control the temperature <120°C) at 80°C with stirring (stirring rate 150 rpm) for 2.5 hours, then raise the temperature to reflux (165°C), separate the generated water through a water separator, react for 5.5 hours, cool (to 45°C), and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:2; The catalyst is 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:3.0; The mass ratio of mesitylene to phenol is 1.1:1; The amount of catalyst used is 0.7% of the mass of phenol; B. Methanol was added to the first crude product (the mass ratio of methanol to the first crude product was 4:1), and then activated carbon was added (the amount of activated carbon was 2% of the quality of the first crude product), stirred at 60°C (stirring rate 150 rpm) for 2 h, then filtered while hot, and the filtrate was cooled to 10°C (gradient cooling: stage 1 was cooled to 40°C, kept warm for 1 h, and stirred at a rate of 100 rpm during the process; stage 2 was cooled to 20°C, kept warm for 1 h, and stirred at a rate of 150 rpm during the process; stage 3 was cooled to 10°C, kept warm for 1.5 h until crystallization was completed, and stirred at a rate of 100 rpm during the process, with intermittent stirring, stirring for 1 minute every 10 minutes), allowed to stand, and centrifuged (centrifugal speed 4000 rpm, centrifugal time 20 min, centrifugal temperature 10°C) to obtain a second crude product, which was then recrystallized and dried in vacuo at 60°C for 6 h to obtain bisphenol S with a yield of 97.9% (based on sulfuric acid), a purity of 99.8% (HPLC analysis method), and a chromaticity of No. 15 (platinum-cobalt colorimetric method); The recrystallization adopts methanol aqueous solution to dissolve the second crude product (the mass ratio of methanol aqueous solution to the second crude product is 6:1), then heats to 60°C and stirs for 3.5 hours, cools to 15°C and stirs to crystallize for 2.5 hours, stands, and centrifuges (centrifugal speed 4000 rpm, centrifugal time 20 minutes, centrifugal temperature 15°C); the initial volume ratio of methanol to water in the methanol aqueous solution is 1:2, and after stirring for 1 hour, water is gradually added to the volume ratio of methanol to water to 1:3.

[0023] Example 2 An improved method for synthesizing high-purity bisphenol S comprises the following steps: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid dropwise (control the temperature <120°C) at 80°C with stirring (stirring rate 150 rpm) for 2.5 hours, then raise the temperature to reflux (165°C), separate the generated water through a water separator, react for 5.5 hours, cool (to 45°C), and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:2; The catalyst is 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:3.0; The mass ratio of mesitylene to phenol is 1.2:1; The amount of catalyst used is 0.6% of the mass of phenol; B. Methanol was added to the first crude product (the mass ratio of methanol to the first crude product was 5:1), and then activated carbon was added (the amount of activated carbon was 2% of the quality of the first crude product), stirred at 55°C (stirring rate 150 rpm) for 2 h, then filtered while hot, and the filtrate was cooled to 10°C (gradient cooling: stage 1 was cooled to 40°C, kept warm for 1 h, and stirred at a rate of 100 rpm during the process; stage 2 was cooled to 20°C, kept warm for 1 h, and stirred at a rate of 150 rpm during the process; stage 3 was cooled to 10°C, kept warm for 1.5 h until crystallization was completed, and stirred at a rate of 100 rpm during the process, with intermittent stirring, stirring for 1 minute every 10 minutes), allowed to stand, and centrifuged (centrifugal speed 4000 rpm, centrifugal time 20 min, centrifugal temperature 10°C) to obtain a second crude product, which was then recrystallized and dried in vacuo at 55°C for 5 h to obtain bisphenol S with a yield of 97.2% (based on sulfuric acid), a purity of 99.6% (HPLC analysis method), and a chromaticity of No. 18 (platinum-cobalt colorimetric method); The recrystallization adopts methanol aqueous solution to dissolve the second crude product (the mass ratio of methanol aqueous solution to the second crude product is 5:1), then heats to 55°C and stirs for 3.5 hours, cools to 15°C and stirs to crystallize for 2 hours, stands, and centrifuges (centrifugal speed 4000 rpm, centrifugal time 20 minutes, centrifugal temperature 15°C); the initial volume ratio of methanol to water in the methanol aqueous solution is 1:2, and after stirring for 1 hour, water is gradually added to the volume ratio of methanol to water to 1:3.

[0024] Example 3 An improved method for synthesizing high-purity bisphenol S comprises the following steps: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid dropwise (control the temperature <120°C) at 85°C with stirring (stirring rate 100 rpm) for 2.0 hours, then raise the temperature to reflux (165°C), separate the generated water through a water separator, react for 5 hours, cool (to 50°C), and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:2.2; The catalyst is 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:3.0; The mass ratio of mesitylene to phenol is 1.2:1; The amount of catalyst used is 0.8% of the mass of phenol; B. Methanol was added to the first crude product (the mass ratio of methanol to the first crude product was 5:1), and then activated carbon was added (the amount of activated carbon was 1% of the quality of the first crude product), stirred at 60°C (stirring rate 100 rpm) for 2.5 hours, and then filtered while hot. The filtrate was cooled to 8°C (gradient cooling: stage 1 was cooled to 40°C, kept warm for 1 hour, and stirred at a rate of 100 rpm during the process; stage 2 was cooled to 20°C, kept warm for 1 hour, and stirred at a rate of 150 rpm during the process; stage 3 was cooled to 8°C, kept warm for 1.5 hours until crystallization was completed, and stirred at a rate of 100 rpm during the process. Intermittent stirring was used, and stirring was carried out for 1 minute every 10 minutes), the mixture was allowed to stand, and centrifuged (centrifugal speed 3000 rpm, centrifugal time 25 minutes, centrifugal temperature 8°C) to obtain a second crude product, which was then recrystallized and dried in vacuo at 55°C for 6 hours to obtain bisphenol S with a yield of 97.5% (based on sulfuric acid), a purity of 99.8% (HPLC analysis method), and a chromaticity of 20 (platinum-cobalt colorimetric method); The recrystallization adopts methanol aqueous solution to dissolve the second crude product (the mass ratio of methanol aqueous solution to the second crude product is 7:1), then heats to 60°C and stirs for 3 hours, cools to 20°C and stirs to crystallize for 3 hours, stands, and centrifuges (centrifugal speed 4000 rpm, centrifugal time 20 minutes, centrifugal temperature 20°C); the initial volume ratio of methanol to water in the methanol aqueous solution is 1:2, and after stirring for 1 hour, water is gradually added to the volume ratio of methanol to water to 1:3.

[0025] Example 4 An improved method for synthesizing high-purity bisphenol S comprises the following steps: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid (controlled at <120°C) dropwise at 75°C with stirring (stirring rate 200 rpm) for 3.0 hours, then raise the temperature to reflux (162°C), separate the generated water through a water separator, react for 6 hours, cool (to 40°C), and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:1.9; The catalyst is 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:3.1; The mass ratio of mesitylene to phenol is 1.0:1; The amount of catalyst used is 0.7% of the mass of phenol; B. Methanol was added to the first crude product (the mass ratio of methanol to the first crude product was 3:1), and then activated carbon was added (the amount of activated carbon was 2% of the mass of the first crude product), stirred at 60°C (stirring rate 200 rpm) for 2 h, then filtered while hot, and the filtrate was cooled to 10°C (gradient cooling: stage 1 was cooled to 40°C, kept warm for 1 h, and stirred at a rate of 100 rpm during the process; stage 2 was cooled to 20°C, kept warm for 1 h, and stirred at a rate of 150 rpm during the process; stage 3 was cooled to 10°C, kept warm for 1.5 h until crystallization was completed, and stirred at a rate of 100 rpm during the process, with intermittent stirring, stirring for 1 minute every 10 minutes), and centrifuged (centrifugal speed 5000 rpm, centrifugal time 15 min, centrifugal temperature 10°C) to obtain a second crude product, which was then recrystallized and dried in vacuo at 60°C for 5 h to obtain bisphenol S with a yield of 97.0% (based on sulfuric acid), a purity of 99.7% (HPLC analysis method), and a chromaticity of 22 (platinum-cobalt colorimetric method); The recrystallization adopts methanol aqueous solution to dissolve the second crude product (the mass ratio of methanol aqueous solution to the second crude product is 6:1), then heats to 60°C and stirs for 4 hours, cools to 15°C and stirs for crystallization for 2.5 hours, stands, and centrifuges (centrifugal speed 4000 rpm, centrifugal time 20 minutes, centrifugal temperature 15°C); the initial volume ratio of methanol to water in the methanol aqueous solution is 1:2, and after stirring for 1 hour, water is gradually added to the volume ratio of methanol to water to 1:3.

[0026] Comparative Example 1 Compared with Example 1, the only difference is that the catalyst uses 4-fluorobenzenesulfonic acid, as follows: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid dropwise (control the temperature <120°C) at 80°C with stirring (stirring rate 150 rpm) for 2.5 hours, then raise the temperature to reflux (165°C), separate the generated water through a water separator, react for 5.5 hours, cool (to 45°C), and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:2; The catalyst is 4-fluorobenzenesulfonic acid; The mass ratio of mesitylene to phenol is 1.1:1; The amount of catalyst used is 0.7% of the mass of phenol; B. Methanol was added to the first crude product (the mass ratio of methanol to the first crude product was 4:1), and then activated carbon was added (the amount of activated carbon was 2% of the mass of the first crude product), stirred at 60°C (stirring rate 150 rpm) for 2 h, then filtered while hot, and the filtrate was cooled to 10°C (gradient cooling: stage 1 cooling to 40°C, holding for 1 h, stirring rate 100 rpm during the process; stage 2 cooling to 20°C, holding for 1 h, stirring rate 150 rpm during the process; stage 3 cooling to 10°C, holding for 1.5 h until crystallization was completed, stirring rate 100 rpm during the process, intermittent stirring, stirring for 1 minute every 10 minutes), allowed to stand, centrifuged (centrifugal speed 4000 rpm, centrifugal time 20 min, centrifugal temperature 10°C) to obtain a second crude product, which was then recrystallized and dried in vacuo at 60°C for 6 h to obtain bisphenol S with a yield of 95.6% (based on sulfuric acid), a purity of 94.4% (HPLC analysis method), and a chromaticity of 35 (platinum-cobalt colorimetric method); The recrystallization adopts methanol aqueous solution to dissolve the second crude product (the mass ratio of methanol aqueous solution to the second crude product is 6:1), then heats to 60°C and stirs for 3.5 hours, cools to 15°C and stirs to crystallize for 2.5 hours, stands, and centrifuges (centrifugal speed 4000 rpm, centrifugal time 20 minutes, centrifugal temperature 15°C); the initial volume ratio of methanol to water in the methanol aqueous solution is 1:2, and after stirring for 1 hour, water is gradually added to the volume ratio of methanol to water to 1:3.

[0027] Comparative Example 2 Compared with Example 1, the only difference is that the catalyst uses 1,5-naphthalene disulfonic acid, as follows: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid dropwise (control the temperature <120°C) at 80°C with stirring (stirring rate 150 rpm) for 2.5 hours, then raise the temperature to reflux (165°C), separate the generated water through a water separator, react for 5.5 hours, cool (to 45°C), and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:2; The catalyst is 1,5-naphthalene disulfonic acid; The mass ratio of mesitylene to phenol is 1.1:1; The amount of catalyst used is 0.7% of the mass of phenol; B. Methanol was added to the first crude product (the mass ratio of methanol to the first crude product was 4:1), and then activated carbon was added (the amount of activated carbon was 2% of the mass of the first crude product), stirred at 60°C (stirring rate 150 rpm) for 2 h, then filtered while hot, and the filtrate was cooled to 10°C (gradient cooling: stage 1, cooling to 40°C, holding for 1 h, stirring rate 100 rpm during the process; stage 2, cooling to 20°C, holding for 1 h, stirring rate 150 rpm during the process; stage 3, cooling to 10°C, holding for 1.5 h until crystallization was completed, stirring rate 100 rpm during the process, intermittent stirring, stirring for 1 minute every 10 minutes), allowed to stand, centrifuged (centrifugal speed 4000 rpm, centrifugal time 20 min, centrifugal temperature 10°C) to obtain a second crude product, which was then recrystallized and dried in vacuo at 60°C for 6 h to obtain bisphenol S with a yield of 92.3% (based on sulfuric acid), a purity of 98.2% (HPLC analysis method), and a chromaticity of 30 (platinum-cobalt colorimetric method); The recrystallization adopts methanol aqueous solution to dissolve the second crude product (the mass ratio of methanol aqueous solution to the second crude product is 6:1), then heats to 60°C and stirs for 3.5 hours, cools to 15°C and stirs to crystallize for 2.5 hours, stands, and centrifuges (centrifugal speed 4000 rpm, centrifugal time 20 minutes, centrifugal temperature 15°C); the initial volume ratio of methanol to water in the methanol aqueous solution is 1:2, and after stirring for 1 hour, water is gradually added to the volume ratio of methanol to water to 1:3.

[0028] Comparative Example 3 Compared with Example 1, the only difference is that the catalyst uses 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:2.5, as follows: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid dropwise (control the temperature <120°C) at 80°C with stirring (stirring rate 150 rpm) for 2.5 hours, then raise the temperature to reflux (165°C), separate the generated water through a water separator, react for 5.5 hours, cool (to 45°C), and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:2; The catalyst is 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:2.5; The mass ratio of mesitylene to phenol is 1.1:1; The amount of catalyst used is 0.7% of the mass of phenol; B. Methanol was added to the first crude product (the mass ratio of methanol to the first crude product was 4:1), and then activated carbon was added (the amount of activated carbon was 2% of the mass of the first crude product), stirred at 60°C (stirring rate 150 rpm) for 2 h, then filtered while hot, and the filtrate was cooled to 10°C (gradient cooling: stage 1 was cooled to 40°C, kept warm for 1 h, and stirred at a rate of 100 rpm during the process; stage 2 was cooled to 20°C, kept warm for 1 h, and stirred at a rate of 150 rpm during the process; stage 3 was cooled to 10°C, kept warm for 1.5 h until crystallization was completed, and stirred at a rate of 100 rpm during the process, with intermittent stirring, stirring for 1 minute every 10 minutes), allowed to stand, and centrifuged (centrifugal speed 4000 rpm, centrifugal time 20 min, centrifugal temperature 10°C) to obtain a second crude product, which was then recrystallized and dried in vacuo at 60°C for 6 h to obtain bisphenol S with a yield of 95.0% (based on sulfuric acid), a purity of 99.1% (HPLC analysis method), and a chromaticity of 23 (platinum-cobalt colorimetric method); The recrystallization adopts methanol aqueous solution to dissolve the second crude product (the mass ratio of methanol aqueous solution to the second crude product is 6:1), then heats to 60°C and stirs for 3.5 hours, cools to 15°C and stirs to crystallize for 2.5 hours, stands, and centrifuges (centrifugal speed 4000 rpm, centrifugal time 20 minutes, centrifugal temperature 15°C); the initial volume ratio of methanol to water in the methanol aqueous solution is 1:2, and after stirring for 1 hour, water is gradually added to the volume ratio of methanol to water to 1:3.

[0029] Comparative Example 4 Compared with Example 1, the only difference is that the catalyst uses 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:3.5, as follows: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid dropwise (control the temperature <120°C) at 80°C with stirring (stirring rate 150 rpm) for 2.5 hours, then raise the temperature to reflux (165°C), separate the generated water through a water separator, react for 5.5 hours, cool (to 45°C), and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:2; The catalyst is 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:3.5; The mass ratio of mesitylene to phenol is 1.1:1; The amount of catalyst used is 0.7% of the mass of phenol; B. Methanol was added to the first crude product (the mass ratio of methanol to the first crude product was 4:1), and then activated carbon was added (the amount of activated carbon was 2% of the mass of the first crude product), stirred at 60°C (stirring rate 150 rpm) for 2 h, then filtered while hot, and the filtrate was cooled to 10°C (gradient cooling: stage 1 was cooled to 40°C, kept warm for 1 h, and stirred at a rate of 100 rpm during the process; stage 2 was cooled to 20°C, kept warm for 1 h, and stirred at a rate of 150 rpm during the process; stage 3 was cooled to 10°C, kept warm for 1.5 h until crystallization was completed, and stirred at a rate of 100 rpm during the process, with intermittent stirring, stirring for 1 minute every 10 minutes), allowed to stand, and centrifuged (centrifugal speed 4000 rpm, centrifugal time 20 min, centrifugal temperature 10°C) to obtain a second crude product, which was then recrystallized and dried in vacuo at 60°C for 6 h to obtain bisphenol S with a yield of 94.7% (based on sulfuric acid), a purity of 99.2% (HPLC analysis method), and a chromaticity of 24 (platinum-cobalt colorimetric method); The recrystallization adopts methanol aqueous solution to dissolve the second crude product (the mass ratio of methanol aqueous solution to the second crude product is 6:1), then heats to 60°C and stirs for 3.5 hours, cools to 15°C and stirs to crystallize for 2.5 hours, stands, and centrifuges (centrifugal speed 4000 rpm, centrifugal time 20 minutes, centrifugal temperature 15°C); the initial volume ratio of methanol to water in the methanol aqueous solution is 1:2, and after stirring for 1 hour, water is gradually added to the volume ratio of methanol to water to 1:3.

[0030] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An improved method for synthesizing high-purity bisphenol S, characterized in that: The steps include: A. Mix mesitylene, phenol, and a catalyst, add concentrated sulfuric acid dropwise under stirring at a temperature of 75-85°C for 2.0-3.0 hours, then raise the temperature to reflux, separate the generated water through a water separator, react for 5-6 hours, cool, and filter to obtain a first crude product; wherein the molar ratio of sulfuric acid to phenol is 1:1.9-2.2; The catalyst is 4-fluorobenzenesulfonic acid and 1,5-naphthalene disulfonic acid in a mass ratio of 5:3.0-3.1; The mass ratio of mesitylene to phenol is 1.0-1.2:1; The amount of catalyst used is 0.6-0.8% of the mass of phenol; B. Add methanol to the first crude product, then add activated carbon, stir at 55-60°C for 2-2.5 hours, then filter while hot, cool the filtrate to 8-10°C, stir and crystallize for 3-4 hours, centrifuge to obtain a second crude product, then recrystallize and dry to obtain bisphenol S.

2. The improved method for synthesizing high-purity bisphenol S according to claim 1, wherein: The reflux temperature is 160-165°C.

3. The improved method for synthesizing high-purity bisphenol S according to claim 1, wherein: In the step B, the filtrate is cooled to 8-10°C by gradient cooling, and the gradient cooling steps include cooling to 30-40°C and keeping warm for 0.5-1h; then cooling to 20°C and keeping warm for 0.5-1h; and finally cooling to 8-10°C and keeping warm for 1-3h.

4. The improved method for synthesizing high-purity bisphenol S according to claim 1, wherein: In the step B, the mass ratio of methanol to the first crude product is 3-5:

1.

5. The improved method for synthesizing high-purity bisphenol S according to claim 1, characterized in that: The amount of activated carbon used is 1% to 2% of the first coarse quality.

6. The improved method for synthesizing high-purity bisphenol S according to claim 1, characterized in that: The stirring speeds in both step A and step B are 100-200 rpm.

7. The improved method for synthesizing high-purity bisphenol S according to claim 1, characterized in that: In step B, the centrifugal speed is 3000-5000 rpm, the centrifugal time is 15-25 min, and the centrifugal temperature is 8-10°C.

8. The improved method for synthesizing high-purity bisphenol S according to claim 1, characterized in that: The recrystallization adopts methanol aqueous solution to dissolve the second crude product, then heats up to 55-60° C. and stirs for 3-4 hours, cools to 15-20° C. and stirs to crystallize for 2-3 hours.

9. The improved method for synthesizing high-purity bisphenol S according to claim 8, characterized in that: The initial volume ratio of methanol to water in the methanol aqueous solution was 1:

2. After stirring for 1 hour, water was gradually added until the volume ratio of methanol to water was 1:

3.

10. The improved method for synthesizing high-purity bisphenol S according to claim 1, characterized in that: The drying step comprises vacuum drying at 55-60° C. for 5-6 hours.