| CPC C07C 319/06 (2013.01) [C07C 319/28 (2013.01); C07B 2200/13 (2013.01)] | 3 Claims |

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1. A preparation method of 3-mercaptopropionic acid, wherein the preparation method consists of the following steps:
(1) Sulfuration: mixing sodium acrylate with sodium hydrosulfide, dissolving the mixture with water, and reacting;
(2) Decomposition: adding sodium sulfide and sulfur powder and further reacting;
(3) Acidification: after completion of the above reactions, cooling, crystallizing, and acidifying with an acid to obtain a solution of 3-mercaptopropionic acid; and
(4) Extracting the obtained solution of 3-mercaptopropionic acid, and then distilling under reduced pressure to obtain 3-mercaptopropionic acid;
wherein, the sodium acrylate has a mass percentage of sodium acrylate of >99%; the sodium hydrosulfide has a mass percentage of sodium hydrosulfide of 70%; the sodium sulfide has a mass percentage of sodium sulfide of 60%; and the sulfur powder has a mass percentage of sulfur powder of 99%;
wherein
in Step (1), the reaction temperature is in the range of 40-80° C.; the reaction pressure is in the range of 0.01-1.5 MPa; and the reaction time is in the range of 0.5-20 h;
in Step (2), the reaction temperature of the decomposition reaction is in the range of 100-150° C.; the reaction pressure of the decomposition reaction is in the range of 0.01-1.5 MPa; and the reaction time of the decomposition reaction is in the range of 0.5-20 h;
in Step (3), when acidifying with the acid, the acidifying temperature is in the range of 0-100° C., and the acidifying time is in the range of 0.5-5 h;
in Step (1), a molar ratio of the sodium hydrosulfide to the sodium acrylate is in the range of 0.1-10:1;
in Step (2), a molar ratio of the sodium sulfide to the sodium acrylate is in the range of 0.1-10:1;
in Step (2), a molar ratio of the sulfur powder to the sodium acrylate is in the range of 0.01-1:1; and
in Step (3), a molar ratio of the acid to the sodium acrylate is in the range of 0.1-5:1.
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