Conformational studies of 2-butanol using temperature-dependent Raman measurements and MM3 calculations

Temperature-dependent Raman measurements between 190 and 358 K yield conformational enthalpy differences between 550 and 690 cal mol(-1) for racemic liquid 2-butanol. The conformational properties of 2-butanol were also studied using MM2 and MM3 calculations. The conformer 1, where C1 and C4 are in anti position, was found to be the most stable comformer with the MM3 calculations. Conformer 2, which has C1 and O5 in anti arrangement, has ca. 500 cal mol(-1) higher energy than 1. Comparisons of the calculated MM3 vibrational frequencies with the Raman spectra suggest that the most stable conformer in the liquid phase also adopts a C1,C4 anti conformation. (C) 1997 Elsevier Science B.V.