Interaction of Aluminium Halides with the Xylenes

Abstract

RECENTLY¹, it has been suggested that the study of equilibria between the aromatic hydrocarbons² in the presence of aluminium halides might be complicated by the formation of stable complexes between the aluminium halide and some of the hydrocarbons. If, as has been shown¹, the heat of complex formation varies considerably with different hydrocarbons, then the composition of the equilibrium mixture of free hydrocarbons will be different from the composition of the mixture of hydrocarbons in the complex. This may lead to uncertainty in the equilibrium concentrations of hydrocarbons, if, as in much of the experimental work described in the literature^{2, 3}, only the total hydrocarbon, including both the free hydrocarbon and that obtained by decomposing the complex, is analysed, since this may result in equilibria which appear to vary with the ratio of aluminium halide to hydrocarbon. Some recent exploratory experiments of ours are of interest in this connexion.