Method for preparing 3-mercaptopropionic acid by efficiently catalyzing acrylic acid-hydrogen sulfide addition reaction through organic phosphine
By combining an organophosphorus catalyst and an ethylene glycol monoether solvent, the reaction conditions of acrylic acid-hydrogen sulfide were controlled to suppress the formation of byproducts, thus achieving the preparation of 3-mercaptopropionic acid with high yield and high purity. This solved the problems of low reaction yield and high purification difficulty in existing processes.
Patent Information
- Application Number
- CN202511459170.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-13
- Publication Date
- 2026-01-13
AI Technical Summary
The existing acrylic acid-hydrogen sulfide process has harsh reaction conditions, resulting in low yield of 3-mercaptopropionic acid and the formation of many byproducts, which increases the difficulty of separation and purification and significantly affects the color index of the product.
An organophosphorus catalyst was combined with an ethylene glycol monoether solvent. The reaction temperature and pressure were controlled by adding the catalyst dropwise through a constant pressure titrator and an autoclave. A polymerization inhibitor was used to suppress the formation of byproducts. Hydrogen sulfide gas was introduced in two stages, and an acrylic acid raw material mixture was added dropwise.
Achieving a 3-mercaptopropionic acid yield of over 98% at lower reaction temperatures and pressures, with a product purity exceeding 99.8%, simplifies the separation and purification process.
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Abstract
Description
TECHNICAL FIELD
[0001] The embodiment of the present application relates to the field of catalytic synthesis of mercapto compounds, and particularly relates to a method for efficiently catalyzing addition reaction of acrylic acid and hydrogen sulfide by organic phosphorus to prepare 3-mercaptopropionic acid. BACKGROUND
[0002] 3-mercaptopropionic acid is a key intermediate for the synthesis of fenleu medicine, and its application field is continuously expanding in recent years, and has been widely used in chain transfer agent in the synthesis of polycarboxylic acid water reducing agent, chalcopyrite- galena flotation separation inhibitor and composite material surface functional modifier and the like. At present, the industrialization route of 3-mercaptopropionic acid in China mainly includes acrylonitrile-sodium sulfide method, acrylic acid-thiourea method and acrylic acid-sodium sulfide method. Although these process routes can achieve high yield of 3-mercaptopropionic acid, they have significant defects such as complex process flow and large amount of three wastes.
[0003] The process for preparing 3-mercaptopropionic acid by reacting acrylic acid with hydrogen sulfide has the advantages of high atom utilization rate, simple process flow and low raw material cost. However, the main technical challenge of this process is to inhibit the generation of by-products such as 3,3'-thiodipropionic acid, acrylic acid polymer, mercaptopropionic acid polymer and 3,3'-dithiodipropionic acid. The existence of these by-products not only significantly increases the separation and purification difficulty of 3-mercaptopropionic acid product, but also greatly affects its color index and refractive index characteristics.
[0004] Patent CN111018757B reports a process for catalyzing addition reaction of acrylic acid and hydrogen sulfide by using triethylamine in an autoclave reactor, which requires low temperature control before reaction and has low yield of 3-mercaptopropionic acid. Patent CN117447369A discloses a method for preparing 3-mercaptopropionic acid by catalyzing Michael addition reaction of acrylic acid and hydrogen sulfide with an acidic catalyst in a fixed bed reactor, which can obtain high reaction yield of 3-mercaptopropionic acid, but the reaction temperature is too high and the reaction pressure is large, resulting in significant increase of equipment investment cost and energy consumption. SUMMARY
[0005] The present application aims at the defects of harsh reaction conditions and low reaction yield of 3-mercaptopropionic acid in the existing acrylic acid-hydrogen sulfide process, and invents a method for efficiently catalyzing addition reaction of acrylic acid and hydrogen sulfide by organic phosphorus to prepare 3-mercaptopropionic acid, so that 3-mercaptopropionic acid reaction liquid with a yield of more than 98% can be obtained at a lower reaction temperature and pressure, and 3-mercaptopropionic acid product with a purity of more than 99.8% can be obtained through vacuum rectification process.
[0006] A method for preparing 3-mercaptopropionic acid by a highly efficient organophosphorus catalytic addition reaction of acrylic acid and hydrogen sulfide, the preparation process comprising: dividing the reaction solvent into two parts, one part of which is mixed evenly with acrylic acid and a polymerization inhibitor and then transferred to a constant pressure titrator, and the other part of which is mixed evenly with an organophosphorus catalyst and then transferred to a high pressure reactor; after the constant pressure titrator is connected to the high pressure reactor, an inert gas is first introduced to replace the air in the reactor, and then a reducing gas and hydrogen sulfide gas are introduced sequentially and the pressure is maintained for a certain period of time, followed by the dropwise addition of a raw material mixture containing acrylic acid; after the dropwise addition of the raw material mixture is completed, hydrogen sulfide is introduced again and the reaction is carried out at a certain temperature and pressure.
[0007] In this technical solution, the organophosphorus catalyst includes one or more of the following: trimethylphosphorus, triethylphosphorus, tri-n-butylphosphorus, tri-tert-butylphosphorus, triphenylphosphorus, methyldiphenylphosphorus, tricyclohexylphosphorus, tri-p-tolylphosphorus, tris(4-methoxyphenyl)phosphorus, dicyclohexylphenylphosphorus, and tris(2,4,6-trimethylyl)phosphorus. These catalysts exhibit significant steric hindrance, effectively suppressing the formation of the byproduct 3,3'-thiodipropionic acid.
[0008] In this technical solution, the reaction solvent includes one or more of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoallyl ether, and ethylene glycol mono-n-propyl ether. The ethylene glycol monoether solvent allows the 3-mercaptopropionic acid intermediate to be stably formed at relatively low reaction temperatures and pressures. It is worth noting that, in addition to the aforementioned ethylene glycol monoethers, other ethylene glycol monoethers are also within the scope of protection of this patent.
[0009] In this technical solution, the polymerization inhibitor includes one or more of 2,6-di-tert-butyl-4-methylphenol, 4,4-dihydroxybiphenyl, phenothiazine, and benzoquinone. Adding a polymerization inhibitor to the raw materials can effectively inhibit the formation of acrylic polymers and 3-mercaptopropionic acid polymers during the reaction process.
[0010] In this technical solution, the reducing gases include H2, CO, and SO2, and the system pressure after introducing the reducing gases is 0.005–0.02 MPa. Introducing reducing gases into the reaction system can reduce the oxidation of the organophosphorus catalyst and the main product 3-mercaptopropionic acid.
[0011] In this technical solution, the system pressure after the first introduction of hydrogen sulfide gas into the autoclave is 0.05–0.1 MPa, and the system pressure after the second introduction of hydrogen sulfide gas into the autoclave is 0.15–0.3 MPa. Introducing hydrogen sulfide gas in two stages can suppress the formation of the byproduct 3,3'-thiodipropionic acid.
[0012] In this technical solution, the mass fraction of acrylic acid in the constant pressure titrator in the solvent is 10% to 90%, preferably 40% to 80%.
[0013] In this technical solution, the mass fraction of the organophosphorus catalyst in the solvent in the autoclave is 1% to 10%, preferably 6% to 10%.
[0014] In this technical solution, the mass ratio of the solvent in the constant pressure titrator to the solvent in the autoclave is 0.2–1, preferably 0.7–1. Using a dropwise addition method that mixes part of the reaction solvent with acrylic acid can reduce the adverse effects of the heat of chemical reaction generated during the mixing of acrylic acid and the catalyst on the reaction.
[0015] In this technical solution, the dropping rate of the raw material mixture in the constant pressure titrator is 0.5 to 3 mL / min, preferably 0.5 to 1 mL / min.
[0016] In this technical solution, the amount of polymerization inhibitor added is 5-90 ppm, preferably 50-80 ppm.
[0017] In this technical solution, the reaction temperature is 25-40℃, preferably 30-35℃.
[0018] In this technical solution, the reaction holding time is 8 to 24 hours, preferably 15 to 20 hours.
[0019] Based on the above invention, the yield of the addition reaction of acrylic acid and hydrogen sulfide to produce 3-mercaptopropionic acid can reach over 98% under relatively low reaction temperature and pressure. This invention has certain guiding significance for the industrialization of the acrylic acid-hydrogen sulfide route. Detailed Implementation
[0020] Example 1 At room temperature, 7 g of acrylic acid, 10 g of ethylene glycol monomethyl ether, and 50 ppm of 2,6-di-tert-butyl-4-methylphenol were mixed thoroughly and transferred to a constant pressure titrator. 0.8 g of dicyclohexylphenylphosphine and 10 g of ethylene glycol monomethyl ether were mixed thoroughly and transferred to an autoclave. The constant pressure titrator was then connected to the autoclave. Nitrogen gas was first introduced to purge the air from the autoclave, followed by H2 until the system pressure reached 0.01 MPa. Hydrogen sulfide gas was then introduced until the system pressure reached 0.1 MPa, and this pressure was maintained for 1 hour. The constant pressure titrator was then started, and the acrylic acid-containing raw material mixture was added dropwise at a rate of 1 mL / min. After the addition of the raw material mixture was complete, the temperature was programmed to rise to 35°C. Once the system pressure stabilized, hydrogen sulfide gas was introduced again to maintain the reaction pressure at 0.3 MPa. This temperature was maintained for 20 hours, after which the reaction was stopped. The reaction performance was analyzed using high-performance liquid chromatography (HPLC), showing an acrylic acid conversion rate of 98.95% and a 3-mercaptopropionic acid yield of 98.19%. The reaction solution was subjected to vacuum distillation to obtain a 3-mercaptopropionic acid product with a purity of 99.85%. The addition reaction formula of acrylic acid with hydrogen sulfide is as follows:
[0021] Example 2 At room temperature, 12 g of acrylic acid, 15 g of ethylene glycol monoethyl ether, and 70 ppm of 4,4-dihydroxybiphenyl were mixed thoroughly and transferred to a constant pressure titrator. 1 g of dicyclohexylphenylphosphine and 15 g of ethylene glycol monoethyl ether were mixed thoroughly and transferred to an autoclave. The constant pressure titrator was then connected to the autoclave. Nitrogen gas was first introduced to purge the air from the autoclave, followed by H2 until the system pressure reached 0.01 MPa. Hydrogen sulfide gas was then introduced until the system pressure reached 0.1 MPa and maintained at this pressure for 1 h. The constant pressure titrator was then started, and the acrylic acid-containing raw material mixture was added dropwise at a rate of 0.8 mL / min. After the addition of the raw material mixture was completed, the temperature was programmed to rise to 35 °C. Once the system pressure stabilized, hydrogen sulfide gas was introduced again to maintain the reaction pressure at 0.3 MPa. The reaction was stopped after maintaining this temperature for 20 h. Performance analysis using high-performance liquid chromatography (HPLC) showed that the conversion rate of acrylic acid was 99.37%, and the yield of 3-mercaptopropionic acid was 98.07%. The reaction solution was subjected to vacuum distillation to obtain 3-mercaptopropionic acid product with a purity of 99.81%.
[0022] Example 3 At room temperature, 7 g of acrylic acid, 10 g of ethylene glycol monobutyl ether, and 50 ppm of benzoquinone were mixed thoroughly and transferred to a constant pressure titrator. 0.8 g of tris(4-methoxyphenyl)phosphine and 10 g of ethylene glycol monobutyl ether were mixed thoroughly and transferred to an autoclave. The constant pressure titrator was then connected to the autoclave. Nitrogen gas was first introduced to purge the air from the autoclave, followed by CO to bring the system pressure to 0.01 MPa. Hydrogen sulfide gas was then introduced to bring the system pressure to 0.1 MPa and maintained at this pressure for 1 h. The constant pressure titrator was then started, and the acrylic acid-containing mixture was added dropwise at a rate of 1 mL / min. After the addition of the mixture was complete, the temperature was programmed to 35 °C. Once the system pressure stabilized, hydrogen sulfide gas was introduced again to maintain the reaction pressure at 0.3 MPa. The reaction was stopped after maintaining this temperature for 20 h. High performance liquid chromatography (HPLC) analysis showed that the conversion rate of acrylic acid was 99.02%, and the yield of 3-mercaptopropionic acid was 98.24%. The reaction solution was subjected to vacuum distillation to obtain 3-mercaptopropionic acid with a purity of 99.83%.
[0023] Example 4 At room temperature, 7 g of acrylic acid, 10 g of ethylene glycol monoallyl ether, and 50 ppm of 2,6-di-tert-butyl-4-methylphenol were mixed thoroughly and transferred to a constant pressure titrator. 1 g of tris(2,4,6-trimethylyl)phosphine and 10 g of ethylene glycol monoallyl ether were mixed thoroughly and transferred to an autoclave. The constant pressure titrator was then connected to the autoclave. Nitrogen gas was first introduced to purge the air from the autoclave, followed by SO2 until the system pressure reached 0.01 MPa. Hydrogen sulfide gas was then introduced until the system pressure reached 0.1 MPa, and this pressure was maintained for 1 h. The constant pressure titrator was then started, and the acrylic acid-containing raw material mixture was added dropwise at a rate of 1 mL / min. After the addition of the raw material mixture was complete, the temperature was programmed to rise to 35°C. Once the system pressure stabilized, hydrogen sulfide gas was introduced again to maintain the reaction pressure at 0.3 MPa. This temperature was maintained for 20 h before the reaction was stopped. The reaction performance was analyzed using high-performance liquid chromatography (HPLC), showing that the conversion rate of acrylic acid was 99.43% and the yield of 3-mercaptopropionic acid was 98.41%. The reaction solution was then subjected to vacuum distillation to obtain a 3-mercaptopropionic acid product with a purity of 99.88%.
[0024] Example 5 At room temperature, 15 g of acrylic acid, 15 g of ethylene glycol mono-n-propyl ether, and 70 ppm of phenothiazine were mixed thoroughly and transferred to a constant pressure titrator. 1.2 g of tri-p-tolylphosphine and 15 g of ethylene glycol mono-n-propyl ether were mixed thoroughly and transferred to an autoclave. The constant pressure titrator was then connected to the autoclave. Nitrogen gas was first introduced to purge the air from the autoclave, followed by H2 until the system pressure reached 0.01 MPa. Hydrogen sulfide gas was then introduced until the system pressure reached 0.1 MPa and maintained at this pressure for 1 h. The constant pressure titrator was then started, and the acrylic acid-containing raw material mixture was added dropwise at a rate of 1 mL / min. After the addition of the raw material mixture was completed, the temperature was programmed to rise to 35 °C. Once the system pressure stabilized, hydrogen sulfide gas was introduced again to maintain the reaction pressure at 0.35 MPa. The reaction was stopped after maintaining this temperature for 20 h. Performance analysis using high-performance liquid chromatography (HPLC) showed that the conversion rate of acrylic acid was 99.28%, and the yield of 3-mercaptopropionic acid was 98.65%. The reaction solution was subjected to vacuum distillation to obtain 3-mercaptopropionic acid product with a purity of 99.91%.
[0025] Table 1
[0026] Comparative Example 1 The solvent in Example 1 was replaced with an equal mass of N,N-dimethylacetamide, while all other conditions remained unchanged. The reaction performance was analyzed using high-performance liquid chromatography (HPLC), showing an acrylic acid conversion rate of 90.37% and a 3-mercaptopropionic acid yield of 85.98%.
[0027] Comparative Example 2 The solvent in Example 1 was replaced with an equal mass of methanol, while all other conditions remained unchanged. The reaction performance was analyzed using high-performance liquid chromatography (HPLC), showing an acrylic acid conversion rate of 80.76% and a 3-mercaptopropionic acid yield of 74.40%.
[0028] Comparative Example 3 The catalyst in Example 1 was replaced with an equal mass of triethylamine, while all other conditions remained unchanged. The reaction performance was analyzed using high-performance liquid chromatography (HPLC), showing an acrylic acid conversion of 85.43% and a 3-mercaptopropionic acid yield of 77.72%.
[0029] Comparative Example 4 The catalyst in Example 1 was replaced with an equal mass of methylphosphine, while all other conditions remained unchanged. The reaction performance was analyzed using high-performance liquid chromatography (HPLC), revealing an acrylic acid conversion of 50.41% and a 3-mercaptopropionic acid yield of 28.67%.
[0030] Comparative Example 5 At room temperature, 7 g of acrylic acid, 20 g of ethylene glycol monomethyl ether, and 0.8 g of dicyclohexylphenylphosphine were mixed thoroughly and transferred to an autoclave. Nitrogen gas was first introduced to purge the air from the autoclave, followed by H2 until the system pressure reached 0.01 MPa. Hydrogen sulfide gas was then introduced until the system pressure reached 0.1 MPa, and this pressure was maintained for 1 h. The temperature was programmed to 35 °C, and after the system pressure stabilized, hydrogen sulfide gas was introduced again to maintain the reaction pressure at 0.3 MPa. The reaction was stopped after maintaining this temperature for 20 h. Performance analysis using high-performance liquid chromatography (HPLC) showed that the conversion rate of acrylic acid was 99.49%, and the yield of 3-mercaptopropionic acid was 75.08%.
[0031] Comparative Example 6 At room temperature, 7 g of acrylic acid, 10 g of ethylene glycol monomethyl ether, and 50 ppm of 2,6-di-tert-butyl-4-methylphenol were mixed thoroughly and transferred to a constant pressure titrator. 0.8 g of dicyclohexylphenylphosphine and 10 g of ethylene glycol monomethyl ether were mixed thoroughly and transferred to an autoclave. The constant pressure titrator was then connected to the autoclave. Nitrogen gas was introduced to purge the air from the autoclave. The constant pressure titrator was started, and the acrylic acid-containing raw material mixture was added dropwise at a rate of 1 mL / min. After the addition of the raw material mixture was completed, the temperature was programmed to 35 °C. Once the system pressure stabilized, hydrogen sulfide gas was introduced to maintain the reaction pressure at 0.3 MPa. The reaction was stopped after 20 h. Performance analysis using high-performance liquid chromatography (HPLC) showed that the conversion rate of acrylic acid was 92.89%, and the yield of 3-mercaptopropionic acid was 73.78%.
[0032] Table 2
[0033] The above embodiments and comparative examples are only used to describe the technical solutions of the present invention. Any substitutions or modifications made by those skilled in the art to the principles of the invention are within the protection scope of the present invention.
Claims
1. A method for preparing 3-mercaptopropionic acid by the addition reaction of organophosphorus catalyzed acrylic acid with hydrogen sulfide, characterized in that, Includes the following steps: (1) Mix acrylic acid, polymerization inhibitor and solvent evenly to obtain a mixture containing acrylic acid, and transfer it to a constant pressure titrator; (2) Mix the organophosphorus catalyst with the solvent to obtain a solution containing the organophosphorus catalyst, and transfer it to an autoclave; (3) Connect the constant pressure titrator to the high pressure vessel, first purge the reaction system with inert gas, then introduce reducing gas and hydrogen sulfide gas in sequence and maintain pressure; (4) Start the constant pressure titrator and add the acrylic acid mixture at a constant rate; (5) After the addition is complete, hydrogen sulfide gas is introduced again to carry out the addition reaction and 3-mercaptopropionic acid is obtained.
2. The method according to claim 1, characterized in that, The organophosphorus catalyst is selected from one or more of trimethylphosphorus, triethylphosphorus, tri-n-butylphosphorus, tri-tert-butylphosphorus, triphenylphosphorus, methyl diphenylphosphorus, tricyclohexylphosphorus, tri-p-tolylphosphorus, tri(4-methoxyphenyl)phosphorus, dicyclohexylphenylphosphorus, and tri(2,4,6-trimethylyl)phosphorus.
3. The method according to claim 1, characterized in that, The polymerization inhibitor is selected from one or more of 2,6-di-tert-butyl-4-methylphenol, 4,4-dihydroxybiphenyl, phenothiazine, and benzoquinone.
4. The method according to claim 1, characterized in that, The solvent is an ethylene glycol monoether, selected from one or more of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoallyl ether, and ethylene glycol mono-n-propyl ether.
5. The method according to claim 1, characterized in that, The reducing gas is selected from hydrogen, carbon monoxide, or sulfur dioxide, and the system pressure after it is introduced is 0.005–0.02 MPa.
6. The method according to claim 1, characterized in that, The system pressure after the first introduction of hydrogen sulfide is 0.05–0.1 MPa, and the system pressure after the second introduction of hydrogen sulfide is 0.15–0.3 MPa.
7. The method according to claim 1, characterized in that, In the constant pressure titrator, the mass fraction of acrylic acid in the solvent is 10%–90%, the amount of polymerization inhibitor is 5–90 ppm, and the dropping rate is 0.5–3 mL / min.
8. The method according to claim 1, characterized in that, The mass fraction of the organophosphorus catalyst in the solvent in the autoclave is 1% to 10%, and the mass ratio of the solvent in the constant pressure titrator to the solvent in the autoclave is 0.2 to 1.
9. The method according to claim 1, characterized in that, The reaction temperature is 25–40℃, and the reaction time is 8–24 h.
10. The method according to claim 1, characterized in that, The inert gas is nitrogen or argon.
Citation Information
Patent Citations
Synthesis method of 3-mercaptopropionic acid
CN117447369A