Etude de la stabilisation du polychlorure de vinyle avec des molecules modeles—II: Action des phosphites et des phosphines sur la degradation du Chloro-4-hexene-2

Phosphines are inhibitors of thermal degradation of 4-chloro-2-hexene because they form strong complexes with either HCl or ZnCl₂, which cause catalysis of the dehydrochlorination. Aliphatic phosphines are more efficient than aromatic phosphines. Aliphatic phosphites also act as stabilizers; they react with HCl, and may be substituted for allylic chlorine in the presence of ZnCl₂ as catalyst; the resulting phosphonate may be destroyed by HCl if phosphite is not in excess. Aromatic phosphites do not react at 60°; they only form a complex with HCl and, in the presence of ZnCl₂, they cause an increase of the dehydrochlorination rate. This effect is due to the reverse reaction, catalysed by a complex HCl-hexadiene, being slowed down because of the competing phosphite-HCl complex.