Conformational Analysis and Dipole Moments of Dialkyl Esters of Some Simple Dicarboxylic Acids

Abstract

Conformational energies of the dimethyl esters of a series of dicarboxylic acids CH3OOC(CH2)nCOOCH3 (n = 1-4 and 8) were calculated by using semiempirical potential energy functions. Dipole moments of these compounds were evaluated and compared with the experimental results. Various models, which have been proposed for the conformation around the C-C-϶C(O)-O bond in the literature, were taken into consideration. The observed values of the dipole moment were found to be reasonably reproduced by two models: one expressed in the six-state scheme and the other in the three-state scheme. The latter model has provided a better explanation for the dielectric behavior of diethyl succinate, which is known to be abnormal. This model is also compatible with that suggested by Moravie and Corset. Both models, however, failed to give an agreement with experiment in the trans-gauche energy difference for diethyl succinate. © 1993, IEEE. All rights reserved. © 1984, American Chemical Society. All rights reserved.