Matrix Isolation and Computational Study on the Photolysis of CHCl2COCl

UV light photolysis of dichloroacetyl chloride (CHCl2COCl) has been investigated by infrared spectroscopy in cryogenic Ar, Kr, Xe, and O2 matrices. The formation of CHCl3 and CO was found to be the dominant process over the ketene formation. The C-C bond cleaved products CHCl2 and COCl were also observed. As the number of the chlorine atom substitution to methyl group of acetyl chloride increased, the C-C bond cleaved product yield in the triplet state increased, which can be attributed to an internal heavy-atom effect where the intersystem crossing rate was enhanced.