The mechanistic route for pyrolysis reaction of S-methyl benzenylmethylenehydrazine dithiocarboxylate has been investigated by density functional theory calculation. Calculation results show that the hydrogen on the eniminic group is kinetically more favorable to migrate to the thiocarbamine sulfur via a six-membered ring transition state TS-1b, than the thiocarbamine hydrogen via four-membered ring transition states in the pyrolytic elimination process. The electronic effect of the substituent on the phenyl group at para-position also affects the reaction by varying the calculated energy barrier.

Key words: pyrolysis, mechanism, density functional theory, electronic effect