Reactivity of Anthracene in Liquid SbCl3 ‐ AlCl3 ‐ N ‐ ( 1 ‐ Butyl ) Pyridinium Chloride Mixtures

Abstract

Mixtures of and N‐(1‐butyl)pyridinium chloride (BPCl) containing and mixtures containing and were found to be liquid at 25°C. Dilute solutions of anthracene were stable in ternary mixtures containing , but in mixtures containing , anthracene reacted under the influence of the solvent, which behaved as both oxidant and H‐transfer catalyst. The oxidized product was protonated anthracene, which was stable in this melt. The source of protons was provided by hydrogen liberating Scholl condensations combined with the reduction of Sb(III). A part of the hydrogen from Scholl reactions reacted with anthracene to form 9,10‐dihydroanthracene. By contrast, a liquid mixture without , (2:1 mole ratio) proved to be a much less active H‐transfer catalyst than the liquids even though it is a stronger Lewis acid, and it did not induce protonation beyond a trace attributable to protic impurities. The role of impurities in these mixtures was investigated with results that are relevant to earlier investigations of liquid mixtures. An improved procedure for purifying BPCl is described.