Free radical substitution in aliphatic compounds. part XXVI. the gas-phase bromination of halogenocycloalkanes

The gas-phase bromination of hatogenocyclohexanes gave the expected isomeric bromohalogenocyclohexanes, together with cyclohexene, bromocyclohexane, and traces of trans-1,2-dibromocyclohexane. These latter products were formed as a result of elimination of hydrogen halide from the starting material. The initial halogenocyclohexanes were shown to undergo elimination of hydrogen halide in the presence of hydrogen bromide. Variation of the surface :volume ratio had a pronounced effect on the elimination which suggested that this reaction had a large heterogeneous component. Bromination of chloro- and fluoro-cyclopentane also produced elimination products which were formed as a result of the reaction of hydrogen bromide with the halogenocyclopentane.