Gas‐phase thermolysis of sulfur compounds. Part IV. n‐propyl allyl sulfide

Abstract

The pyrolysis of n-propyl allyl sulfide has been studied in static and stirred-flow systems at temperatures between 270 and 400°C. Propene and 2,4,6-triethyl-1,3,5-trithiane were the only reaction products. The order of the reaction was 0.99 f 0.05 a t 377OC. The firstorder rate coefficients followed the Arrhenius equationThe rate coefficients and the product distribution remained unchanged when cyclohexene was used as carrier gas. A molecular mechanism involving a six-centered cyclic transition state is proposed to explain the present results. This mechanism is further supported by the pyrolysis of 4-thia-5-dideutero-1-heptene at 377OC, where only 3-deuteropropene is formed. The kinetic deuterium isotope effect had a value of 2.6 f 0.3 a t this temperature. The results are compared with those obtained in the pyrolysis of n-butyl allyl sulfide previously reported.

DFT Calculations on Retro-Ene Reactions Part I: Allyl n-Butyl Sulfide Pyrolysis in the Gas Phase

“…The negative calculated activation entropies show that ABS pyrolysis proceeds through a concerted cyclic TS, which has been confirmed experimentally. 11,12…”

“…Gas phase pyrolysis reactions of allyl n-butyl sulfide (ABS) and its deuterated derivative have been experimentally studied at temperatures between 262 and 293 o C. 11,12 According to Scheme 2, this reaction obeys a first order rate law and the elimination products are propene and n-butyl thioaldehyde.…”