Conformational Stability of (+)-Epichlorohydrin

Abstract

Vibrational absorption and circular dichroism spectra of (+)-epichlorohydrin have been recorded for the neat liquid and in organic solvents CCl4, CS2, CHCl3, CH2Cl2, and CH3I. These spectra are compared with the ab initio predictions of absorption and vibrational circular dichroism (VCD) spectra obtained with density functional theory using the B3LYP/6-311G(2d,2p) basis set for three different conformers of (S)-epichlorohydrin. The Boltzmann populations, obtained from Gibbs free energies, indicate that the populations of gauche-II, gauche-I, and cis conformers for isolated molecule are 65, 32, and 3%, respectively. The analysis of experimental and theoretical absorption data indicates that the population ratios of conformers gauche-II:gauche I:cis are: ∼35.7%:∼54.6%:9.7% (neat liquid); ∼58.6%:∼34.0%:7.4% (CCl4); ∼51.0%:∼40.6%:8.4% (CS2); ∼46.1%:∼44.8%:9.1% (CHCl3); ∼42.2%:∼48.5%:9.3% (CH3I); ∼37.2%:∼53.3%:9.5% (CH2Cl2). These compositions are consistent with the experimental VCD spectra. This information...