Polymerization of alkylene oxides with trialkylaluminum, metal acetylacetonates, and water

Trialkylaluminum and acetylacetonates of Groups II and III metals are very effective polymerization catalysts for alkylene oxides. Addition of water increased both polymerization rate and yield. Among many combinations examined, a combination of triisobutylaluminum, zinc acetylacetonate, and water is outstanding. It gives high rate, high yield, and high degree of polymerization. The mole ratio of these three components was extensively studied and shown to be less critical than for other systems. Order of addition was not important. Elastomeric products based on propylene oxide, ethylene oxide, epichlorohydrin, and allyl glycidyl ether were prepared in high yield in relatively short reaction times. Copolymerization rates for epichlorohydrin–ethylene oxide and epichlorohydrin–propylene oxide were determined and indicated that this catalyst is anionic in character. It is concluded that the bimetallic nature of this catalyst is responsible for its high reactivity, versatility and stereochemistry.