Mixed metal vinyl stabilizer synergism—reactions with model compounds

An allylic model compound for degrading PVC, cinnamyl chloride, was found to react with metal carboxylates in n‐butyl acetate at 50°C with rates first order in each component. The corresponding metal chlorides and a mixture of rearranged and unrearranged allyl esters were isolated. With cadmium carboxylates, the rate constant is of the order of 300 × 10 −5 sec −1 ; with barium carboxylates, two orders of magnitude slower. In the presence of excess barium carboxylate, the rate of reaction is first order in cadmium and independent of barium concentration; the product is, however, barium chloride. Under such conditions, only unrearranged allyl ester is recovered. These observations are interpreted in terms of a rapid step leading to formation of a carboxylate‐bridged barium/cadmium intermediate. It is proposed that such intermediates displace chloride from allylic carbon by a concerted mechanism, generating chloride‐bridged reaction products that collapse exclusively to barium chloride.