Study of the Stabilization of Polyvinyl Chloride) by Using Model Molecules. VI. Mechanism of Reactions of Aminocrotonate Esters

The mechanism of reaction of the β-aminocrotonate of butanediol (βACB) with 4-chloro-2-hexene (4C2H), a model compound for the allylic chlorine in polyvinyl chloride), was studied in THF or dichloroethane at 60°C by gas and liquid chromatography. The reaction, which needs ZnCl2 as a catalyst, leads to substitution products through the primary amine group and the hydrogen atom of the trisubstituted double bond. βACB reacts with HCl to give NH4Cl and a set of complex organic products. NH4Cl and the substitution products are able to complex ZnCl, inhibiting its catalytic activity. In combination with other stabilizers, βACB strongly induces the substitution reaction versus the dehydro-chlorination. In the polymer at 190°C, it increases very much the time of action of the stabilizers; it acts as an HC1 acceptor but also it may be substituted on the polymer even without catalysts. Synergistic effects are observed with epoxy compounds or indole derivatives.