CONFORMATIONAL EQUILIBRIA OF ALPHA-SUBSTITUTED CARBONYL-COMPOUNDS - STUDY OF SOLVENT EFFECTS

PM3 computations have been performed to study conformational equilibri a of a series of alpha-substituted carbonyl compounds in solution. The solvent is taken into account in the calculations by using cavity mod els. The compounds studied are a series of substituted acetaldehydes C H2R-CHO and cyclohexanones C6H9OR (R = F, Cl, Br, CN, NO2). The predic ted solvent effects are in agreement with available experimental data. The discussion emphasizes the role played by the multipole moments an d the necessity of going beyond the ellipsoidal cavity shape approxima tion in the case of substituted cyclohexanones.