Heteroaromatic rings as substituents. Part III. The electronic effects of the 2-furyl group

Abstract

The substituent parameters for the 2-furyl group have been determined by measuring the pK_a values of the meta- and para-furyl-substituted benzoic acids and phenols in aqueous ethanol and the rate constants for the solvolysis of the appropriate 1-arylethyl acetates in aqueous 30% ethanol. The 2-furyl group shows a moderate electron-withdrawing inductive effect and is able either to withdraw or to release electrons by a resonance effect. A comparison is made with the electronic effect of the 2-thienyl group.