Theoretical study on the mechanism of chloroacetyl chloride decomposition

Abstract

The mechanism of chloroacetyl chloride (CH2ClCOCl) decomposition has never been investigated by theoretical and experimental methods before, which is explored at the BMC-CCSD//BMK/6-311+G(d, p) level in this work. Eight pathways and ten transition states are located to search for more favorable pathways. Some dissociated pathways start from the trans-CH2ClCOCl directly. Alternatively, the trans-CH2ClCOCl would transform to the cis-CH2ClCOCl. Then, the cis-CH2ClCOCl would dissociate into the product with single or multi steps. Starting from the trans-CH2ClCOCl, P1 (CHClCO+HCl) is the most favorable product by the rupture of C1H1 bond and C2Cl2 bond and the formation of H1Cl2 bond (Pathway 1), due to the least step and the lowest barrier height. P2 (CH2Cl2+CO) is the common product of both Pathway 2 and Pathway 4 those start from the trans- and cis-CH2ClCOCl, respectively. Owing to the second lowest rate-determining barrier height, P2 is the second feasible product. P3 (CH2Cl(O)CCl) formed by the migration of O atom from C2 atom to Cl1 atom is the most minor product because of the highest barrier height. Other products P4 (CH2Cl+CO+Cl), P5 (CH2CO+Cl2), and P6 (CH2ClCO(Cl)) formed by the attack of Cl2 atom to C1 atom, Cl1 atom, and O atom, respectively, are not energetically accessible because of higher barrier-consumed and/or complicated process.