Transformation of thiols to disulfides via an oxidant-free radical pathway on the zeolite ETS-10

Radical coupling of thiols is an attractive route for the synthesis of disulfides, but this approach should be promoted by oxidants and/or metal salts in combination with environmentally harmful additives, which limits its substrate scope and industrial application. The ETS-10 zeolite was found to be able to catalyze the conversion of thiols to radicals with high efficiency in the absence of an oxidant or any additives for the synthesis of symmetrical disulfides. In this developed approach, the electrophilic H of the thiols interacts with the electron-rich O in the -Ti-O-Ti- unit of ETS-10, leading to the formation of a colinear SH-O bonded complex. Electron transfer occurs from O to S, resulting in the homolysis of the S-H bond to generate sulfur radicals followed by dimerization.