GAS-PHASE THERMOLYSIS OF N-(TERT-BUTYLTHIO)ALLYLAMINE AND N-(TERT-BUTYLTHIO)DIETHYLAMINE

The title sulphenamides were pyrolysed in a stirred-flow reactor at temperatures of 310-410 degrees C, pressures of 8-15 Torr and residence times of 0.4-2 s using toluene as the carrier gas. N-(tert-Butylthio)allylamine formed 73 +/- 4% isobutene, 23 +/- 3% propene and N-allylthiohydroxylamine. The first-order rate coefficients for the formation of isobutene and propene, respectively, followed the Arrhenius equations K-C4(s(-1)) = 10(12.52+/-0.36) exp(-163 +/- 5 kJ mol(-1) RT) and k(c3)(s(-1))propene, 10(10.99+/-0.29) exp(-151 +/- 4 kJ mol(-1) RT). N-(tert-butylthio)diethylamine gave 97 +/- 1% isobutene, 1.9 +/- 0.4% isobutane and N,N-diethylthiohydroxylamine. The first-order rate coefficients for isobutene elimination followed the Arrhenius equation k(s(-1)) = 10(13.45+/-0-24) exp(-164 +/- 3 kJ mel(-1) RT). The formation of the products is interpreted in terms of an elimination reaction with a unimolecular, four-centered, cyclic transition state. The reactivity of these sulphenamides was found to be much higher than that of previously studied alkyl or aryl tert-butyl sulphides and disulphides.