Vibrational spectra and conformations of (bromomethyl)cyclopropane and epibromohydrin

Abstract

Abstract Infrared and Raman spectra of (bromomethyl)cyclopropane and epibromohydrin have been recorded. Reversible spectral changes which accompany changes in temperature indicate the existence of an equilibrium mixture of gauche and cis conformers for (bromomethyl)cyclopropane. The gauche form is more stable, and from the variable temperature studies an enthalpy difference of 2.0±0.2 kcal mol −1 has been obtained for the liquid phase. For epibromohydrin, two non‐equivalent gauche conformers have been identified, and the gauche‐1 form is more stable than the gauche‐2 by 0.80±0.20 kcal mol −1 in the liquid phase. Additionally there is evidence for a third conformer, presumably the cis form, but characterization of this conformer has been limited by the complexity of the spectra associated with the gauche ‐1 and gauche ‐2 forms. Consequently, only a lower limit can be given for the Δ H separating the cis and gauche ‐1 conformers. The results are consistent with previous observations for similar molecules.