Features of the mechanism of initiation of polymerization of ε-caprolactone on exposure to complex compounds of metal halides

Complex compounds of ammonium and phosphonium salts and metal halides have been studied as catalysts of the polymerization of ε-caprolactone. It was established that the complex salts in the lactone medium break down in equilibrium with formation of the free metal halide. The formation of the polymer complexes with the metal halide leads at 150–180°C to the formation of active centres. The reaction system has a “pseudoliving” character.