Polymerization of epoxides with dialkylaluminum acetylacetonate catalyst systems

Abstract

AbstractCatalyst systems for the polymerization of epichlorohydrin, propylene oxide, and allyl glycidyl ether have been prepared from pure, separately synthesized dialkylaluminum acetylacetonates (R2Alacac). Adding small amounts of water to R2Alacac gives a catalyst system with enhanced activity. An even more active catalyst system for yielding high molecular weight, epichlorohydrin‐containing polymers is obtained when another organometallic compound is added to the R2Alacac‐0.5 water components. The R2Alacac‐0.5 water‐R2Zn system has been studied in detail. Variation in the molar proportion of water and structural changes in the chelate structure of the R2Alacac component have been examined. Results indicate that the bis‐chelate structure, acac(R)‐Al‐O‐Al(R)acac, plays a major role in catalyst formation. A bimetallic catalyst species containing aluminum and zinc atoms is proposed, with zinc functioning primarily in monomer coordianation and with aluminum involved primarily in polymer chain growth.