THE SOLVENT EFFECT ON THE CONFORMATIONAL EQUILIBRIA OF 4-SUBSTITUTED CYCLOHEXENES

Conformational preferences have been measured for 4-X-cyclohexenes (X = Br, Cl, CHO, COOH) in a series of solvents with increasing polarity The conformational equilibrium exhibits a very weak solvent dependence, Delta G varies at most by 0.25 kcal mol(-1) (1 kcal = 4.184 kJ) shifting from a non-polar mixture (CS2-CDCl3) to highly polar (CD3)(2)SO. The reaction field theory was used to calculate the variation of Delta G with solvent polarity, The calculated solvent shifts delta Delta G are small and in agreement with the values determined experimentally.