A kind of preparation method of β-mercapto carboxylic acid compound

Abstract

The invention provides a preparation method of a beta-sulfhydryl carboxylic acid compound. A solid base catalyst used in the method has suitable alkali strength, so that not only is hydrogen sulfide enabled to be activated and a reaction promoted to be carried out, but the binding between carboxyl groups and active sites in raw materials or products is also inhibited, and the active sites are prevented from being deactivated slowly. Furthermore, the solid base catalyst selects a polyhydroxy compound as a carrier, and a great deal of hydroxyl groups on the surface of the carrier can promote thehydrogen sulfide to be dissolved in a reaction system and adsorbed on the surface of the catalyst so as to enable the hydrogen sulfide to be migrated to the positions around the active sites for being activated, so that the high conversion rate and high selectivity of the reaction also can be enabled to be reached at the lower pressure, and the catalytic stability is better. In addition, the preparation method is mild in reaction conditions, and the gas-liquid phase reaction is carried out under the conditions of low temperature and low pressure, so that the method is easily applied to industry. Experiments prove that the reaction conversion rate and selectivity of the beta-sulfhydryl carboxylic acid compound prepared by the method are respectively not less than 98% and 88%. After the compound is continuously evaluated for 100h, the catalytic stability of the compound is proved to be better.

Description

technical field [0001] The invention relates to the technical field of preparing mercapto compounds, in particular to a method for preparing β-mercapto carboxylic acid compounds. Background technique [0002] β-Mercapto carboxylic acid compounds are an important class of organic chemical intermediates, which are widely used in the preparation of pharmaceutical intermediates, daily chemicals, optical resins, and can also be used as chain transfer agents for free radical polymerization, etc., with a broad application market . For example: 3-mercaptopropionic acid is an intermediate of the medicine Fennarol, and is widely used as a chain transfer agent in the preparation of polycarboxylate superplasticizers. Mercaptosuccinic acid is the main component of daily chemical cold perm agent. And the preparation of β-mercaptocarboxylic acid compound takes 3-mercaptopropionic acid as an example, which can be prepared by thiourea method, sodium hydrosulfide method or hydrogen sulfide ...

AI Technical Summary

Problems solved by technology

U.S. Patent US20110004017 reported that using 4A molecular sieve as a catalyst, hydrogen sulfide reacts with acrylic acid or 2-butenoic acid to prepare 3-mercaptopropionic acid or 3-mercaptobutyric acid, the highest reaction selectivity is 87%, and the catalytic stability is poor

U.S. Patent No. 5,008,432 has reported that the use of basic anion resins containing tertiary amines or quaternary ammonium bases or guanidinium groups as catalysts, hydrogen sulfide and acrylic acid to prepare 3-mercaptopropionic acid, the reaction selectivity can exceed 90%, but requires more than 2MPa It can only be realized under reaction pressure, and the reaction conditions are relatively harsh. At the same time, the reaction only has a good effect in DMF, and the catalytic stability is poor in other solvents.