On the mechanism of thermal decomposition of 4-alkyl-5-sulfonylimino-Δ2-1,2,3,4-thiatriazolines

The kinetics of the thermal decomposition of several sulfonyl substituted thiatriazolinimines 1a-g were investigated in different solvents both in the presence and in the absence of trapping reagents. The first-order rate constants observed in all cases, are dependent on the inductive effect of the sulfonyl substituent (R), as well as on solvent polarity, but independent on the nature and concentration of the co-reagent. These results, and the low activation energy, are rationalized by assuming an anchimeric assistance of the sulfonyl group during thermolysis. This would give the intermediate 7 , which collapses to the thiaziridinimine 2 before being trapped by the co-reagent.