Conformational Analysis of (S)-(+)-1-Bromo-2-methylbutane and the Influence of Bromine on Conformational Stability

(S)-(+)-1-bromo-2-methylbutane was investigated using vibrational circular dichroism (VCD). Experimental absorption and VCD spectra of (+)-1-bromo-2-methylbutane in CDCl3 solution were recorded in the 2000−900 cm-1 region, and they were compared with the ab initio predictions of absorption and VCD spectra obtained with density functional theory using the B3LYP/6-31G* basis set for (S)-1-bromo-2-methylbutane. This comparison indicates that (+)-1-bromo-2-methylbutane is of the (S) configuration and exists in several conformations. The results obtained for (S)-(+)-1-bromo-2-methylbutane are also compared to those for (S)-(+)-3-(2-methylbutyl)thiophene, which indicates that the predominant conformations are influenced by the substitution of bromine with thiophene ring.