Dielectric study of esters in benzene: internal rotation and molecular configuration

Abstract

Electric dipole moments (µ) at 25° have been determined for phenethyl butyrate, phenethyl phenylacetate, pentyl benzoate, pentyl formate, and pentyl butyrate at a frequency of 1 MHz, and for phenethyl butyrate, phenethyl phenylacetate, phenylpropyl butyrate, pentyl phenylacetate, and pentyl cinnamate at a microwave frequency of 3·38 GHz. Relaxation times (τ) at 25° have been calculated, and Eyring's equation has been used to obtain values for the heat (ΔH*) and free energy (ΔG*) of activation. The values of µ and τ have been interpreted in terms of internal rotation and molecular configuration.