ABSTRACT
Photolysis, at lambda >/= 310 nm (DeltaE < 387 kJ mol(-1)), of acryloyl chloride 1 isolated in argon matrixes at 10 K yields 3-chloro-1,2-propenone 4 through 1,3-chlorine migration. There is no evidence of cyclopropenone or propadienone formation. 4 is also synthesized by irradiation of 3-chloropropanoyl chloride (lambda >/= 230 nm) isolated in argon matrix at 10 K. Identification is performed by comparison of experimental FT-IR spectrum with calculated ones (ab initio calculations at the 6-31G level). Irradiation of 1 at lambda >/= 230 nm induces the photolysis of 4 which breaks into CO and the postulated transient 2-chloroethylidene 5 and/or into propadienone 2 complexed by HCl. The transient 5 collapses to form ground-state vinyl chloride 6 by 1,2 hydrogen migration. In the next step, 2 loses CO to form a new transient assumed to be vinylidene 7 which yields ethyne by intramolecular isomerization process and vinyl chloride by intermolecular reaction with HCl trapped in the same cage. CO, HCl, ethyne, and vinyl chloride are the final reaction products. Modeling of the 1,3 chlorine migration process from 1 using ab initio calculations at the MP2/6-31G level is performed in the ground state (S(0)) and the first singlet excited state (S(1)). The reaction energy value for an S(1) (509 kJ/mol) state process is higher than for an S(0) process (207.2 kJ/mol), these theoretical results suggesting the reaction take place in the ground state.
