Unimolecular Elimination and the Significance of the Electrical Conduction, Racemization and Halogen Replacement of Organic Halides in Solution

Abstract

THERE are a number of cases in which the development of electrical conductivity in sulphur dioxide solution has been held to indicate the electrolytic dissociation of an alkyl halide. One of the best known examples is that of tert. -butyl iodide¹. We find, however, that tert.-butyl chloride absorbs bromine quantitatively in sulphur dioxide, the products being isobutylene dibromide and hydrogen chloride. This suggests a rather rapidly established equilibrium, Me₃CClMe₂C: CH₂+HCl, in which, however, the left-hand components have the smaller free energy, -Phenylethyl chloride also is said to give a conducting solution in sulphur dioxide: we find that the pure chloride in the pure solvent does not conduct, but that when there is conduction, styrene and hydrogen chloride are present: CHPhMeClCHPh: CH₂+HCl. Under conditions of purity in which the chloride does not conduct, hydrogen chloride itself has negligible conductivity in small concentration, but even in these circumstances the addition of bromine leads to a quantitative yield of styrene dibromide.