Mechanism of polymerization reaction of 2,5-bis(tetrahydrothiopheniomethyl)thiophene dichloride

The polymerization kinetics of 2,5-bis(tetrahydrothiopheniomethyl)thiophene dichloride were studied. The reaction proceeds via a 2,5-dihydrothiophene intermediate M. Results of kinetic and product studies revealed that the 1,6-elimination proceeded by an (E1cb)_irr mechanism. The rate of the disappearance of M was not influenced by the addition of OH^-, carbanions, and tetrahydrothiophene but was accelerated by S₂O₈^2- and inhibited by TEMPO. In addition, the reaction mixture exhibited an electron spin resonance signal with a g value of 2.003 G and induced the polymerization of acrylamide. These results indicated a free radical polymerization mechanism.