Transmission of polar effects. Part XI. Polar and steric effects in the reactions of arylaliphatic carboxylic acids

Abstract

The rate coefficients for the reaction with diazodiphenylmethane in ethanol at 30° and the acid-catalyzed esterification with methanol at 60° of a number of arylaliphatic carboxylic acids and their pKa values in 80% 2-methoxyethanol–water have been measured. Rate coefficients have also been measured for the alkaline hydrolysis in 70% dioxan–water of their 2-diethylaminoethyl esters at 45°. The pKa values and diazodiphenylmethane esterification rate coefficients were also measured for a series of 2-substituted fluorene-9-carboxylic acids. The latter results have been correlated by Hammett equations and the transmission of polar effects in fluorene is discussed. Polar and steric substituent constants are evaluated for the arylaliphatic systems. These values are used to successfully correlate the hydrolysis and ionization reactions using the Taft–Ingold equation.