Method for decolorizing bisphenol S crude product without using activated carbon

Abstract

The invention discloses a method for decolorizing a bisphenol S crude product without using activated carbon, which comprises the following steps: mixing phenol and mesitylene, heating, adding concentrated sulfuric acid, heating, refluxing and separating water; filtering to obtain a bisphenol S crude product; the method comprises the following steps: dissolving a bisphenol S crude product in a mixed solution of alcohol and water, adding sodium sulfite, and heating and refluxing; and filtering while hot, evaporating the filtrate, and filtering to obtain bisphenol S solid. According to the method, a catalyst does not need to be added, a traditional activated carbon adsorption process is replaced by sodium sulfite pigment reduction, the problems that a bisphenol S product is unstable in chromaticity and prone to pink are effectively solved, and the product quality is remarkably improved. According to the method, the crude product is decolorized without using expensive wooden activated carbon, so that the production cost is reduced, no activated carbon solid waste is generated, the solid waste treatment cost of an enterprise is reduced, and the economic benefit of the enterprise is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology production, and specifically relates to a method for decolorizing crude bisphenol S without using activated carbon. Background Technology

[0002] Bisphenol S, chemically known as 4,4'-dihydroxydiphenyl sulfone (4,4'-Sulfonyldiphenol), is a white solid. It is readily soluble in aliphatic hydrocarbons, soluble in alcohols and ethers, slightly soluble in aromatic hydrocarbons, and sparingly soluble in water. Bisphenol S is an important intermediate in pesticides, dyes, and auxiliaries. It is mainly used as a fixing agent, silver plating additive, leather tanning agent, and high-temperature dyeing dispersant. It can also be used in the manufacture of color photographic materials, contrast enhancers, thermal recording materials (developers), daily-use surfactants, and high-efficiency deodorants. Furthermore, bisphenol S can be used as a raw material for polycarbonate, epoxy resins, polyester resins, polysulfone, and polyethersulfone. It can also be added as an additive to various resins to improve their properties. Thermotropic copolyester liquid crystals produced using bisphenol S as a raw material exhibit excellent thermal and machinability properties. In polymer applications, it can replace bisphenol A, which may affect the human endocrine system, and is superior to bisphenol A in both performance and safety. Therefore, the market demand for bisphenol S is substantial.

[0003] Currently, the industrial synthesis methods for bisphenol S (BPS) primarily involve sulfonating phenol with concentrated sulfuric acid, followed by the addition of benzenesulfonic acid as a catalyst, and a condensation reaction to obtain crude BPS (Chinese patent publication number CN110467552B). The crude BPS synthesized using this method has a low purity, generally below 95%. Furthermore, due to the addition of excess phenol during the reaction, it is easily oxidized at high temperatures, turning pink or brownish-red. Commercially available BPS products are required to be white. Therefore, crude BPS requires further decolorization to meet the quality requirements of downstream customers.

[0004] A Chinese patent with publication number CN113651736A mentions a method for decolorizing bisphenol S. In this decolorization and purification method, the decolorization of crude bisphenol S mainly relies on the adsorption of a large amount of activated carbon. The process is complex and energy-intensive, and the use of a large amount of activated carbon causes a huge loss of bisphenol S during the filtration process.

[0005] Therefore, a method for decolorizing crude bisphenol S without using activated carbon is urgently needed. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for decolorizing crude bisphenol S without using activated carbon.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] This invention provides a method for decolorizing crude bisphenol S without using activated carbon, comprising the following steps:

[0009] Step S1: Mix phenol and mesitylene and heat to 90-150 °C. Add concentrated sulfuric acid and heat again to reflux and separate water. React for 3-6 hours.

[0010] Step S2: After the reaction is complete, the reaction solvent mesitylene is removed by filtration at 80-120 °C, so that some isomers and phenol are carried out to obtain crude bisphenol S.

[0011] Step S3: Dissolve crude bisphenol S in a mixed solution of alcohol and water at room temperature, add sodium sulfite, and heat under reflux;

[0012] Step S4: After heating and reflux, filter while hot. Evaporate the filtrate to remove the alcohol from the mixed solvent, and filter to obtain bisphenol S solid.

[0013] Preferably, in step S1, the mass ratio of phenol: concentrated sulfuric acid: mesitylene is 1:0.53:1.

[0014] Preferably, in step S1, the temperature for the second heating is 160~180 ℃.

[0015] Preferably, in step S2, when the reaction solution is cooled to 80~120 ℃, crude bisphenol S is obtained by hot filtration.

[0016] Preferably, in step S3, the mixed solution of alcohol and water used is a methanol-water mixed solution or an ethanol-water mixed solution with a volume ratio of 1:3 to 1:8.

[0017] Preferably, in step S3, the amount of sodium sulfite used is 0.01-0.05 equivalents of phenol.

[0018] Preferably, in step S3, the reflux temperature is 40-90 ℃ and the reflux time is 1-4 h.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention eliminates the need for a catalyst in the synthesis of bisphenol S. By precisely controlling the temperature of the filtration solvent, mesitylene, a portion of the isomers and phenol are separated from the reaction system, yielding a crude product with a purity exceeding 95%. Subsequently, the amount of sodium sulfite, the reducing agent, is further controlled to reduce the pink pigment in the crude bisphenol S. This eliminates the need for activated carbon adsorption and decolorization, thus improving the quality of the bisphenol S product and yielding high-purity, bright white bisphenol S. The crude bisphenol S obtained after the reaction is light in color and does not clump during the experiment, preventing clogging, hindering the flow of the reaction system, reducing product dispersibility, or causing localized overheating and the formation of other impurities.

[0021] The purpose of adding sodium sulfite to the bisphenol S solution in this invention is to reduce and decolorize the pigment o-benzoquinone in crude bisphenol S, thereby purifying bisphenol S and whitening its color. This effectively solves the problem of unstable color and a tendency to appear pink in bisphenol S products, significantly improving product quality. It eliminates the use of expensive wood-based activated carbon for decolorizing the crude product, reducing production costs. Furthermore, the absence of activated carbon solid waste reduces solid waste treatment costs for enterprises, greatly improving their economic benefits. Detailed Implementation

[0022] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0023] Example 1

[0024] S1: First, add 100 g of phenol and 100 g of mesitylene to a four-necked flask. Heat the four-necked flask to 140°C. After reaching the temperature, add 53 g of concentrated sulfuric acid dropwise to the flask using a peristaltic pump (7.5 rpm). After the concentrated sulfuric acid is added, heat the flask again to 165°C and reflux to separate water for 6 hours. The reaction is then complete, and the reaction solution is obtained.

[0025] S2: After the reaction is complete, mesitylene is recovered from the reaction solution. When the reaction solution is cooled to 90 °C, it is filtered while hot to obtain crude bisphenol S with a purity of 96%.

[0026] S3: Add crude bisphenol S to a flask, then add ethanol and water ( 300 mL of a mixed solution of sodium sulfite was dissolved at room temperature, and 1.85 g (0.01 equivalent) of sodium sulfite was added. The mixture was then heated to 80 °C and refluxed for 1 h.

[0027] S4: After heating and reflux, filter while hot. Remove the ethanol from the mixed solvent by passing the filtrate through a rotary evaporator. Filter to obtain white bisphenol S solid with a color of 10 (platinum-cobalt colorimetric method).

[0028] Example 2

[0029] S1: First, add 100 g of phenol and 100 g of mesitylene to a four-necked flask. Heat the four-necked flask to 150°C. After reaching the temperature, add 53 g of concentrated sulfuric acid dropwise to the flask using a peristaltic pump (7.5 rpm). After the concentrated sulfuric acid is added, heat the flask again to 170°C and reflux to separate water for 6 hours. The reaction is then complete, and the reaction solution is obtained.

[0030] S2: After the reaction is complete, mesitylene is recovered from the reaction solution. When the reaction solution is cooled to 100 °C, it is filtered while hot to obtain crude bisphenol S with a purity of 95%.

[0031] S3: Add crude bisphenol S to a flask, then add methanol and water ( 500 mL of a mixed solution of sodium sulfite was dissolved at room temperature, and 3.7 g (0.02 equivalent) of sodium sulfite was added. The mixture was then heated to 60 °C and refluxed for 1 h.

[0032] S4: After heating and reflux, filter while hot. Remove the ethanol from the mixed solvent by passing the filtrate through a rotary evaporator. Filter to obtain white bisphenol S solid with a color of 10 (platinum-cobalt colorimetric method).

[0033] Comparative Example 1

[0034] S1: First, add 100 g of phenol, 100 g of mesitylene, and 10 g of 1,5-naphthalenedisulfonic acid to a four-necked flask. Heat the four-necked flask to 140 ℃. After reaching the temperature, add 53 g of concentrated sulfuric acid dropwise to the flask using a peristaltic pump (7.5 rpm). After the concentrated sulfuric acid is added, heat the flask again to 165 ℃ and reflux to separate water for 6 hours. The reaction is then complete, and the reaction solution is obtained.

[0035] S2: After the reaction is complete, mesitylene is recovered from the reaction solution. When the reaction solution is cooled to 100 °C, it is filtered while hot to obtain crude bisphenol S with a purity of 89%.

[0036] S3: Add crude bisphenol S to a flask, then add ethanol and water ( 500 mL of a mixed solution of sodium sulfite was dissolved at room temperature, and 3.7 g (0.02 equivalent) of sodium sulfite was added. The mixture was then heated to 80 °C and refluxed for 1 h.

[0037] S4: After heating and reflux, filter while hot. Remove the ethanol from the mixed solvent by passing the filtrate through a rotary evaporator. Filter to obtain white bisphenol S solid with a color of 20 (platinum-cobalt colorimetric method).

[0038] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for decolorizing crude bisphenol S without using activated carbon, characterized in that, Includes the following steps: Step S1: Mix phenol and mesitylene and heat to 90-150 °C. Add concentrated sulfuric acid and heat again to reflux and separate water. React for 3-6 hours. Step S2: After the reaction is complete, filter at 80-120 °C to obtain crude bisphenol S; Step S3: Dissolve crude bisphenol S in a mixed solution of alcohol and water at room temperature, add sodium sulfite, and heat under reflux; Step S4: After heating and reflux, filter while hot. Evaporate the filtrate to remove alcohol solvent, and filter to obtain bisphenol S solid.

2. The method for decolorizing crude bisphenol S without using activated carbon according to claim 1, characterized in that, In step S1, the mass ratio of phenol: concentrated sulfuric acid: mesitylene is 1:0.53:

1.

3. The method for decolorizing crude bisphenol S without using activated carbon according to claim 1, characterized in that, In step S1, the temperature for the second heating is 160 ~ 180 ℃.

4. The method for decolorizing crude bisphenol S without using activated carbon according to claim 1, characterized in that, In step S2, when the reaction solution is cooled to 80-120°C, it is filtered while hot to obtain crude bisphenol S.

5. The method for decolorizing crude bisphenol S without using activated carbon according to claim 1, characterized in that, In step S3, the mixed solution of alcohol and water used is a methanol-water mixture or an ethanol-water mixture, with a volume ratio of 1:3 to 1:

8.

6. The method for decolorizing crude bisphenol S without using activated carbon according to claim 1, characterized in that, In step S3, the amount of sodium sulfite used is 0.01-0.05 equivalents relative to phenol.

7. The method for decolorizing crude bisphenol S without using activated carbon according to claim 1, characterized in that, In step S3, the reflux temperature is 40-90 ℃ and the reflux time is 1-4 h.