Method for producing dimethyl 3, 3 '-dithiodipropionate and efficiently recycling byproducts

Abstract

The invention belongs to the technical field of organic synthesis, and particularly provides a synthetic method of dimethyl 3, 3 '-dithiodipropionate and a method for efficiently recycling byproducts. Comprising the following steps: introducing carbon dioxide into a water phase generated by 3, 3 '-dimethyl polythiodipropionate, adding methyl acrylate, slowly adding a sodium polysulfide solution to start a synthetic reaction, controlling the reaction temperature and time, then concentrating external sampling water under negative pressure, and filtering and crystallizing concentrated liquid to obtain sodium thiosulfate. According to the method, the byproduct sodium carbonate is converted into the raw material sodium bicarbonate required by production, recycling of the byproduct is achieved, meanwhile, the sodium thiosulfate aqueous solution generated through reaction is concentrated and crystallized to prepare an industrial-grade product, concentrated external distilled water can be recycled as process water, no waste liquid is generated, the utilization rate of the raw material is increased, and zero emission is achieved. In the process, purification and separation of an intermediate product are not needed, continuous feeding of each step of the product is realized, reaction steps are reduced, and industrial production is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and specifically relates to a method for producing dimethyl 3,3'-dithiodipropionate and efficiently recycling by-products. Background Art

[0002] 3-Isothiazolinone is mainly composed of 2-methyl-4-isothiazoline-3-one and 5-chloro-2-methyl-4-isothiazoline-3-one. It is a low-toxic, broad-spectrum and highly efficient non-oxidizing fungicide. It is widely used in industrial water treatment, cosmetics, building materials, adhesives, coatings, medical and health care, papermaking and textiles due to its high bactericidal efficiency, good degradability, safe operation, good compatibility and low use cost.

[0003] 3-isothiazolinone is mainly synthesized from 3,3' dimethyl dithiodipropionate as a synthetic intermediate through steps such as amide, chlorination ring closure, elimination, and neutralization. The synthesis methods of dimethyl dithiodipropionate have been widely reported both at home and abroad. Patent US3769315 uses methyl acrylate and hydrogen sulfide as raw materials, heats and pressurizes to synthesize methyl mercaptopropionate, and then uses n-heptane as a solvent and chlorine to synthesize dimethyl dithiodipropionate. Patent US5472993 uses methyl acrylate and sodium polysulfide at a low temperature of 0-5°C to generate dimethyl dithiodiacrylate. Li Zhibin's "Fine Chemicals" uses sodium bicarbonate, methyl acrylate, and sodium polysulfide to synthesize dimethyl polythiodipropionate at low temperature, and then treats it with sodium sulfite to obtain dimethyl dithiodipropionate. Patent CN 102180819 A uses methyl acrylate (or methyl methacrylate), sodium bisulfite, sodium bicarbonate and sodium polysulfide solution to synthesize 3,3' dimethyl dithiodipropionate in aqueous solution, and further cools the final synthetic liquid water layer to 0-5°C, so that the byproduct sodium thiosulfate in the synthetic liquid is fully crystallized and precipitated, and the byproduct sodium thiosulfate crystals are obtained by filtration. The remainder is an alkaline solution containing sodium carbonate, which is used as an acid gas absorbent when producing synthetic isothiazolinone. The above processes all have the problems of complex process operation, poor continuity of each step, large amount of waste liquid, large number of byproducts, and serious environmental pollution. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for producing dimethyl 3,3'-dithiodipropionate and efficiently recycling by-products, which solves the problems of purification, separation and discharge of intermediate products.

[0005] A method for producing dimethyl 3,3'-dithiodipropionate and efficiently recycling by-products, wherein the raw materials include methyl acrylate, sodium polysulfide, sodium bicarbonate, sodium sulfite and water, and an industrial-grade sodium thiosulfate product is co-produced. The specific contents are as follows: Initial reaction: raw materials methyl acrylate, sodium bicarbonate and reverse osmosis water are sequentially added into the kettle according to a certain amount of substance ratio, the temperature is controlled at -5~30°C, sodium polysulfide aqueous solution is added dropwise into the reactor under stirring conditions, and the temperature is kept at 10~30°C for 1~3 hours, and the mixture is allowed to stand and separate into two layers: oil phase and water phase: the organic phase is 3,3'-dimethyl polysulfide dipropionate, and the water phase is a sodium carbonate aqueous solution; Add a certain amount of sodium sulfite aqueous solution to the organic phase obtained in step 1), react at room temperature for 5 to 8 hours, and allow to stand to separate into two layers: an oil phase and an aqueous phase: the organic phase is the product dimethyl 3,3'-dithiodipropionate, and the aqueous phase is an aqueous solution of sodium thiosulfate; The aqueous phase obtained in step 2) is evaporated, concentrated, and purified to obtain an industrial-grade sodium thiosulfate product with a content of ≥ 98.0%; A certain volume of carbon dioxide gas is introduced into the aqueous sodium carbonate solution obtained in step 1) to completely convert it into sodium bicarbonate, and then steps 1) to 3) are followed to continuously obtain dimethyl 3,3'-dithiodipropionate and industrial-grade sodium thiosulfate products, while realizing the recycling of the byproduct sodium carbonate obtained in step 1).

[0006] According to the method for producing dimethyl 3,3'-dithiodipropionate and efficiently recycling by-products, in step 1), the molar ratio of methyl acrylate to sodium polysulfide can be selected to be 1:1-1.15, and the molar ratio of methyl acrylate to sodium bicarbonate is 1:1-1.5.

[0007] According to the method for producing dimethyl 3,3'-dithiodipropionate and efficiently recycling by-products, the molar ratio of dimethyl 3,3'-polythiodipropionate to sodium sulfite in the organic phase in step 2) is 1:1.5-2.0, and the mass percentage concentration of the sodium sulfite aqueous solution can be selected to be 15-35%.

[0008] According to the method for producing dimethyl dithiodipropionate and efficiently recycling by-products, in step 4), carbon dioxide is introduced underwater, and the volume and time of the introduced carbon dioxide should be sufficient to convert all the sodium carbonate in the aqueous phase obtained in step 1) into sodium bicarbonate.

[0009] According to the method for producing dimethyl 3,3'-dithiodipropionate and efficiently recycling by-products, the externally evaporated liquid obtained by concentrating the sodium thiosulfate aqueous phase in step 3) can be recycled as reaction water in steps 1) to 4); the sodium thiosulfate purification method is selected to be recrystallization, wherein the single recrystallization yield can reach more than 90%.

[0010] The beneficial effects achieved by the present invention are: The invention introduces carbon dioxide into the by-product to react with the by-product, converts the by-product sodium carbonate into sodium bicarbonate, a raw material required for production, for recycling, concentrates and crystallizes the sodium thiosulfate aqueous solution generated by the reaction to obtain a product that meets industrial grade requirements, and the concentrated externally distilled water can be recycled as process water. The method generates no waste liquid, greatly improves the utilization rate of raw materials, achieves zero emission, and is safe and environmentally friendly.

[0011] The process of synthesizing dimethyl 3,3'-dithiodipropionate by the method of the present invention does not require purification and separation of intermediate products, and continuous feeding of each step of the product is achieved. The operation is simple and easy, the reaction steps are reduced, the reaction efficiency is improved, and industrial production is facilitated. DETAILED DESCRIPTION

[0012] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0013] The sodium polysulfide aqueous solution used as the reaction raw material in the examples is self-made by the company with a specification of about 20%; other raw materials such as methyl acrylate, sodium bicarbonate, sodium sulfite, etc. are all commercially available industrial grade specifications. Example

[0014] Initial reaction: add 450g methyl acrylate, 483.3g sodium bicarbonate and 540g reverse osmosis water into the reactor, control the temperature at -2~5°C, add sodium polysulfide aqueous solution dropwise into the reactor under stirring, keep warm at 28±2°C for 3 hours, and let stand to separate into two layers: the upper organic phase is 330.9g of the intermediate 3,3'-dimethyl polysulfide dipropionate, and the lower aqueous phase is 2335.8g of sodium carbonate aqueous solution with a mass percentage of 23.3%; Take 135 g of dimethyl 3,3'-dithiodipropionate obtained in step 1) above, add 1260 g of a 15% sodium sulfite aqueous solution, react at room temperature for 8 hours, and stand for stratification: the organic phase obtains 232.4 g of the target product 3,3'-dimethyl dithiodipropionate with a purity of 99.80%, and the aqueous phase is 1162.6 g of an aqueous solution of sodium thiosulfate; The aqueous solution containing sodium thiosulfate obtained in the above step 2) was concentrated by evaporation and purified to obtain 143.2 g of industrial grade sodium thiosulfate product with a purity of 98.2%.

[0015] Example 2: Recycling of by-product sodium carbonate, 654.37 g of the by-product sodium carbonate aqueous solution obtained in step 1) of Example 1 was taken, and a certain volume of carbon dioxide gas was introduced into it at a controlled flow rate to obtain 790.6 g of a 33.5% sodium bicarbonate aqueous solution; other operating conditions and feed amounts were the same as those in steps 1) to 3) of Example 1, to obtain 190.47 g of the target product of dimethyl 3,3'-dithiodipropionate with a purity of 99.85%.

[0016] The amount of carbon dioxide introduced is based on the fact that no sodium bicarbonate is precipitated from the system, because too much carbon dioxide introduced into the system will reduce the solubility of sodium bicarbonate in the aqueous solution.

[0017] Example 3: Evaporation concentration and recycling of purified crystal water, 135 g of dimethyl 3,3'-dithiodipropionate, 175 g of sodium sulfite and 1050 g of water were sequentially added to a kettle, wherein the process water was taken from the mixed water of evaporation concentration and purified crystallization after the industrial-grade sodium thiosulfate product was prepared according to the operation mode of step 3) in Example 1, and then reacted at room temperature for 7 hours, and allowed to stand for stratification: the organic phase obtained 231.2 g of the target product 3,3'-dimethyl dithiodipropionate with a purity of 99.76%, and the aqueous phase was 1128.8 g of an aqueous solution of sodium thiosulfate.

[0018] Comparative Example 1 Add 315 ml of deionized water to a 2000 ml three-necked flask, add 252 g of sodium bicarbonate powder and 258 g of methyl acrylate under stirring, pour 350 g of sodium polysulfide solution into a constant pressure funnel, lower the temperature to 0-5°C, and drop the sodium polysulfide solution for 70 min. After the dropwise addition, react at 20-25°C for 240 min. After the reaction, transfer the reaction solution to a liquid separation device to cool and stand, separate the oil layer to obtain 383 g of dimethyl polysulfide dipropionate, and 790 g of the water layer is a byproduct of an aqueous solution of sodium carbonate.

[0019] 630 g of deionized water was added to a 2000 ml three-necked flask, and 340 g of sodium sulfite powder and 383 g of dimethyl dithiodipropionate obtained above were added in sequence under stirring conditions. The reaction was carried out at 20-30° C. for 480 min. After the reaction was completed, the reaction solution was transferred to a liquid separation device for cooling and standing. The oil layer was separated to obtain 295 g of methyl dithiodipropionate, and 1055 g of the water layer was a by-product of an aqueous solution of sodium thiosulfate.

[0020] As can be seen from Examples 1-3, in the present invention, sodium polysulfide is added dropwise after sodium bicarbonate, sodium sulfite and methyl acrylate are put into a kettle to react and produce 3,3'-dimethyl dithiodipropionate, and purification and separation of the intermediate product dimethyl polythiodipropionate are not required, and continuous feeding of each step of the product is achieved, which is simple and easy to operate, reduces the reaction steps, improves the reaction efficiency, and is conducive to industrial production; carbon dioxide is introduced into the by-product for reaction, and the by-product sodium carbonate and sodium thiosulfate aqueous solution are respectively converted into the raw material sodium bicarbonate and concentrated evaporating liquid required for production, wherein sodium sulfite and industrial sodium thiosulfate products, wherein sodium bicarbonate can be used as the reaction raw material of step 1), and the concentrated evaporating liquid is used for the reaction water of step 1) or step 2), and no waste liquid is generated, which greatly improves the raw material utilization rate, achieves zero discharge of by-products, and is safe and environmentally friendly.

[0021] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for synthesizing dimethyl 3,3'-dithiodipropionate and recycling by-products, wherein the raw materials include methyl acrylate, sodium polysulfide, sodium bicarbonate, sodium sulfite and water, and an industrial-grade sodium thiosulfate product is co-produced, characterized in that: The steps include: 1) Initial reaction: put the raw materials methyl acrylate, sodium bicarbonate and reverse osmosis water into the kettle in a certain amount ratio, control the temperature at -5~30℃, add the sodium polysulfide aqueous solution dropwise into the reactor under stirring, keep the temperature at 10~30℃ for 1~3 hours, let it stand and separate into two layers: oil phase and water phase: the organic phase is 3,3'-dimethyl polysulfide dipropionate, and the water phase is the aqueous solution of sodium carbonate; 2) adding a certain amount of sodium sulfite aqueous solution to the organic phase obtained in step 1), reacting at room temperature for 5 to 8 hours, and allowing to stand to separate into two layers: an oil phase and an aqueous phase: the organic phase is the product dimethyl 3,3'-dithiodipropionate, and the aqueous phase is an aqueous solution of sodium thiosulfate; 3) Evaporating and concentrating the aqueous phase obtained in step 2) and purifying it to obtain an industrial grade sodium thiosulfate product with a content of ≥ 98.0%; 4) A certain volume of carbon dioxide gas is introduced into the aqueous sodium carbonate solution obtained in step 1) to completely convert it into sodium bicarbonate, and then the process is performed in the manner of steps 1) to 3) to continuously obtain dimethyl 3,3'-dithiodipropionate and industrial-grade sodium thiosulfate products, while realizing the recycling of the by-product sodium carbonate obtained in step 1).

2. The method for synthesizing dimethyl 3,3'-dithiodipropionate and recycling by-products according to claim 1, characterized in that: In the step 1), the molar ratio of methyl acrylate to sodium polysulfide can be selected to be 1:1-1.15, and the molar ratio of methyl acrylate to sodium bicarbonate is 1:1-1.

5.

3. The method for synthesizing dimethyl 3,3'-dithiodipropionate and recycling by-products according to claim 1, characterized in that: In the step 2), the molar ratio of the organic phase to dimethyl 3,3'-polythiodipropionate and sodium sulfite is 1:1.5-2.0, and the mass percentage concentration of the sodium sulfite aqueous solution can be selected to be 15-35%.

4. The method for synthesizing dimethyl 3,3'-dithiodipropionate and recycling by-products according to claim 1, characterized in that: In the step 4), the carbon dioxide is introduced underwater, and the volume and time of the introduced carbon dioxide should be sufficient to convert all the sodium carbonate in the aqueous phase obtained in the step 1) into sodium bicarbonate.

5. The method for synthesizing dimethyl 3,3'-dithiodipropionate and recycling by-products according to claim 1, characterized in that: The externally evaporated liquid obtained by concentrating the sodium thiosulfate aqueous phase in step 3) can be recycled as reaction water in steps 1) to 4); the sodium thiosulfate purification method is selected to be recrystallization.