THERMAL-DECOMPOSITION OF 3',3'-DICHLOROSPIRO[FLUORENE-9,2'-THIIRANE] - KINETICS AND MECHANISM

Kinetic studies on the thermal decomposition of 2,2-dichloro-3-(9-fluorenylidene)thiirane in 12 solvents have been investigated in detail. A two-term rate equation has been derived to account for the overall rate changes. Both a uni- and bimolecular ionic mechanism involving the concatenation of sulfur atoms is proposed to account for the observed kinetic behavior. Activation parameters were calculated and rationalized with respect to differences in solvation of the ground and transition states. A linear, isokinetic relationship was found indicating a similar mechanism of decomposition in these solvents. Rates of reaction were also found to be linearly correlated with dielectric constant as well as the pi* scale of Kamlet and Taft. The rate of desulfurization is decreased in the presence of acetic acid, and a radical mechanism is discounted from a rate study in the presence of radical inhibitors.