Computational study on the mechanisms and reaction pathways of the CX3O2 + Br (X = F and Cl) reactions

The mechanisms for the reactions of CX3O2 (X = F and Cl) with atomic bromine were studied using quantum chemistry methods. The result indicates that the title reactions could take place on the singlet and triplet potential energy surfaces (PES). On singlet PES, the most favourable product is CX3OOBr (IM1) formed via a barrierless of CX3O2 association with Br. As for the CCl3OO + Br reaction, other products such as CCl3O + BrO, CCl2O + ClOBr, ClOCCl2OBr and CCl2O + Cl + OBr could make certain contributions in different conditions. On the triplet PES, substitution and direct abstraction mechanisms were located, but it could be negligible compared with that on the singlet PES. Time Dependent Density Functional Theory (TDDFT) calculation indicates that CX3OOBr could take photolysis easily under the sunlight.