REACTION PATHS FOR AQUEOUS DECOMPOSITION OF CCL2

The potential energy surface (PES) for the H2O + CCl2 reaction was inv estigated at the ab initio SCF and MP2 levels of theory, employing the DZP basis set, in order to determine the mechanism of basic aqueous d ecomposition of CCl2. Several possible pathways were considered, inclu ding reactions with other H2O molecules and OH-. We have found that th e first step corresponds to insertion of CCl2 into the O-H bond of wat er, resulting in the CHCl2OH species. This molecule loses HCl in one e limination reaction catalyzed by OH-, forming ClCHO. Again, OH- cataly zes the elimination of other HCl, resulting in CO, the decomposition p roduct. The first step is the slow one, and we have used transition-st ate theory to estimate the rate constant for the aqueous decomposition of CCl2, The obtained rate constant was used for building a general p icture of CHCl3, decomposition in basic aqueous solution. The results of the present study are in agreement with experimental observations.