Two distinctive methods for the synthesis of cis- and trans-2, 5-disubstituted-thiazolidin-4-ones via stereoselective cyclo-condensation between α-mercaptocarboxylic esters and arylimines have been developed. With the new reaction used as the key step, two sets of optically active anti-PAF active thiazolidin-4-ones were synthesized.
Use of Mercapto-Methyl Esters as Chain Transfer Agents
申请人:ARKEMA FRANCE
公开号:US20140235807A1
公开(公告)日:2014-08-21
Disclosed herein is a chain transfer agent in a free-radical emulsion polymerization process, of at least one mercapto-methyl ester, and also relates to the free-radical emulsion (co)polymerization process comprising at least one such mercapto-methyl ester and uses thereof. Also disclosed herein are mercapto-methyl diesters.
The present invention relates to a method of preparing a vinyl chloride-based polymer, which includes inducing the nucleation of particles by adding a mercaptan-based chain transfer agent to a monomer composition including a vinyl chloride-based monomer and a preliminary polymerization initiator (preliminary polymerization); and preparing a polymer by mixing a vinyl chloride-based monomer and the particle nuclei and adding a main polymerization initiator (main polymerization). In the preparation method, a vinyl chloride-based polymer having a uniform molecular weight distribution and a desired number average molecular weight may be provided by controlling a degree of polymerization of a vinyl chloride-based polymer prepared in such a way that dispersibility is ensured by adjusting the point of time to add the mercaptan-based chain transfer agent to the point of time to reach a specific conversion rate of the preliminary polymerization.