Gas-phase eliminations. Part VIII. The effect of β-methylation on the pyrolysis of some t-alkyl chlorides

Abstract

A series of t-alkyl chlorides (t-butyl, 1,1-dimethylpropyl, 1,1,2-trimethylpropyl, and 1,1,2,2-tetramethylpropyl) have been pyrolysed to form hydrogen chloride and the appropriate olefin. The kinetics follow a first-order law; the reactions were homogeneous and indifferent to the presence of inhibitors. It is concluded that all these compounds undergo elimination by a unimolecular mechanism; the Arrhenius parameters reported are consistent with this. Rate constant ratios are shown to have the same trend as has been observed in S_N1 solvolysis. The implications of this finding with regard to the nature of the transition state in gas-phase eliminations are discussed.