The infrared (3500–30 cm− 1) spectra of gaseous and solid and the Raman (3500–200 cm− 1) spectra of the liquid with quantitative depolarization ratios and solid trans-3- chloropropenoyl chloride (trans-ClCHCHCClO) have been recorded. These data indicate that both the anti (carbonyl bond trans to the carbon–carbon double bond) and syn conformers are present in the fluid states but only the anti conformer is present in the ...