The pyrolysis of cyclic hydrocarbons. Part 1. 1,4-dimethylcyclohexane

1,4-Dimethylcyclohexane has been pyrolysed in a continuous-flow stirred reactor at 767-835 K and pressures up to 9 Torr (1 200 Pa). The formation of the complex mixture of products is interpreted on the basis of a free-radical chain process, with chains of moderate length (<30). Arrhenius parameters for production of a number of products have been determined, and these are consistent with the proposed mechanism. Considerable radical isomerisation occurs, as shown by the large yields of, for example, butenes, which cannot be produced by direct decomposition of 1,4-dimethylcyclohexyl radicals. The pyrolysis is self-inhibiting, even at low conversion, and secondary reaction of cycloalkene products results in the formation of aromatics.