| Abstract: | There is considerable evidence indicating that the carcinogenic action of vinyl chloride involves metabolic conversion to the epoxide (chlorooxirane) as the initial step. In order to learn more about its subsequent behavior, we have computed structures, energies and other properties for two different protonated forms of the epoxide, and also for two possible rearrangement products, chloroacetaldehyde and acetyl chloride. An ab initio SCF -MO procedure (GAUSSIAN 70) was used. Oxygen protonation is found to weaken both C? O bonds, the effect being greater for the bond involving the carbon bearing the chlorine. Chlorine protonation leads to a marked weakening of the C? Cl bond; this suggests a possible loss of HCl, leaving behind a carbonium ion (and possible alkylating agent or rearrangement precursor). Thus, while C? O bond breaking is doubtless an important reaction pathway for chlorooxirane, our results indicate that attention should also be focused upon the C? Cl bond; its rupture may conceivably be a key step in the biological action of vinyl chloride. |
