Infrared spectra of cyclopropanol and ethenol

Abstract

A study of the infrared spectra of cyclopropanol and ethenol is described. For cyclopropanol, vapour-phase, liquid-phase and carbon tetrachloride solution spectra have been examined and bands attributable to the gauche rotamer assigned. Ab initio predictions of vibrational mode frequencies have been used to guide the assignments in instances where ambiguities arise. For ethenol, ab initio predictions for the bands to be expected in the vapour-phase spectrum are discussed in terms of the syn and anti rotameric forms of the molecule. Unusually large intensity variations of certain bands which accompany changes in torsional angle are highlighted and the consequences of these variations for detection of the gas-phase infrared spectrum of the less abundant anti rotamer are discussed.