Gas‐phase thermolysis of sulfur compounds. Part VIII. Chloromethyl allyl, cyanomethyl allyl, 1‐cyanoethyl allyl and neopentyl allyl sulfides

Abstract

The pyrolyses of four alkyl allyl sulfides with substituents on the a-C atom of the alkyl moiety have been studied in a stirred-flow system over the temperature range 340-400°C and pressures between 2 and 12 torr. The only products formed are propene and thioaldehydes. The reactions showed first-order kinetics with the rate coefficients following the Arrhenius equations:Chloromethyl allyl sulfide: The effects of these and other substituents on the reactivity is discussed in relation with the stabilization of a polar six-centered transition state. The results support a nonconcerted mechanism where the 1-5 a-H atom shift is assisted by its acidic character.

Computational Tests of Models for Kinetic Parameters of Unimolecular Reactions of Organophosphorus and Organosulfur Compounds

“… a CVT/SCT. b VTST-ISPE/SCT. c Ref . d Ref . e Ref . f Ref . g Ref . h Ref . i Ref . j Ref . k Ref . l Ref . m Estimate. n Ref . o Ref . p Ref . q Ref . r Ref . s Ref . t Ref . …”

Transition structure for the retroene-type elimination reaction of propene from allylamines

“…The temperature dependence of the kinetic deuterium isotope effect and a lack of substituent effects on the reaction rate for allyl ethers [4][5][6] were used as evidence to propose a nonplanar transition state and a highly concerted mechanism. The allyl sulfides [7,8], on the other hand, showed a temperature-independent kinetic isotope effect [8] and an important substituent effect [7] on the rate of the pyrolysis, suggesting a polar transition state in which the higher reactivity was due to an enhanced acidic character of the ␣-H atom to be transferred in a nonlinear 1-5 shift path. For the thermal generation of silenes from allylsilanes [3,13,14], a concerted retroene elimination of propene was proposed.…”

“…generation of some carbon-heteroatom double bonds; among these can be cited C‫ס‬O [4][5][6], C‫ס‬S [7,8], C‫ס‬N [9][10][11][12], C‫ס‬Si [13,14], and recently, C‫ס‬P [15,16].…”