Gas-phase eliminations. Part VII. The pyrolysis of substituted 1-phenylethyl chlorides

Abstract

The kinetics of the thermal decompositions of X·C₆H₄·CHClCH₃ into olefin and hydrogen chloride (X =p-Me, m-Me, p-F, H, p-Cl, p-Br, and p-CN) are reported and shown to be homogeneous unimolecular reactions. Arrhenius parameters are listed, together with the rates relative to the unsubstituted compound at 308°. The logarithms of these latter quantities when plotted against σ⁺ yield a straight line of slope –1·4. It is concluded that a moderate degree of charge separation is involved in the transition states of these reactions. An appendix reports and discusses the rate of pyrolysis of 2-phenylethyl chloride and bromide at 425·5° and 385·5° respectively.