LINEAR CORRELATION OF THE BASICITY OF AROMATIC COMPOUNDS WITH SIGMA sigma ⁺ CONSTANTS IN THE HYDROGEN CHLORIDE-ALUMINUM CHLORIDE SYSTEM.

Evaluation of aromatic basicity has attracted considerable interest from various research groups. Basicity increased with the number of methyl group substituents, and the relative basicity correlates linearly with the halogenation rates of the corresponding compounds. However, effect of the substituents other than methyl groups on the aromatic basicity was not included in these studies. Moreover, there has been no report in the literature concerning the use of those readily available substituent constants, sigma **0 and sigma ** plus , to predict the relative basicity of aromatic compounds. In this paper the author reports a simple approach to this solution. Using HCl-AlCl//3 as acceptor, he has measured the relative basicity of twenty-four aromatic compounds including halogen and methoxy substituted compounds. Assuming sigma -nature of the reaction products, it was found that the relative basicity of aromatic compounds excluding those methoxy substituted correlate linearly.