KINETICS OF POLYMERIZATION REACTION OF ALPHA,ALPHA'-BIS(TETRAHYDROTHIOPHENIO)-P-XYLENE DICHLORIDE

Polymerization reactions of alpha,alpha-bis(tetrahydrothiophenio)-p-xy lene dichlorides with OH- in H2O have been studied kinetically. The re actions proceeded via the alpha-tetrahydrothiophenio-p-xylylene interm ediates. Results of the H-D exchange experiments and kinetic studies r eveal that the 1,6-elimination forming the intermediates proceeds reve rsibly via the ylide intermediate. The observed rate of disappearance of the intermediate was increased by the addition of OH-, tetrahydroth iophene, and S2O82- as well as by the photoirradiation with a tungsten lamp in the presence of Rose Bengal and was inhibited by TEMPO. Howev er, the rate was found to be independent of ylide concentration. From these results, an elimination-free radical polymerization mechanism is proposed. The microscopic rate constants for each step of this mechan ism were calculated from the change in the intermediate concentration with time. All of the rate data showed excellent correlations with the substituent constants in the Hammett plot.