Conformational analysis and photolysis of matrix isolated 3-chloropropanoyl chloride monitored by FTIR spectroscopy

Article abstract of DOI:10.1016/S0022-2860(97)00369-4

Fourier transform infrared spectra of 3-chloropropanoyl chloride 1, both as a neat liquid and isolated in an argon matrix at 10 K, have been analyzed. These spectra reveal the existence of three conformers, the SA conformer (φ(1(C3C2C10)) = 0°and φ(2(C1C2C3C13)) = 180°) being the most stable. The semi-empirical PM3 and ab initio 6-31G* methods were used to evaluate the relative stability of these conformers, and to calculate the infrared spectra. Irradiation of 3-chloropropanoyl chloride, at λ > 230 nm, yields 3-chloro-1,2-propenone 2 and acryloyl chloride 3 as primary photoproducts. Photolysis of these compounds induces the formation of CO, HCl, vinyl chloride and ethyne as final products. The shifts of the ν(HCl) stretching mode, below the frequency of monomeric HCl in argon matrix, are indicative of the formation of HCl: CO and HCl: ethyne complexes. The identification of the reaction products is performed by comparison of experimental FTIR spectra and literature data.