Mechanism of ε-Caprolactone polymerization by Aluminum Alkoxides

Pure aluminum isopropoxide was shown to be a highly active catalyst for the polymerization of ε-caprolactone: the overall kinetics of this polymerization follow a first current order in monomer and a first order in catalyst. Mechanistical studies indicate also that this system operates through a selective acyloxygen cleavage of the lactone ring, with insertion in the aluminum-oxygen bond. Moreover, the polymerization proceeds by a perfectly “living” process on catalytic coordination aggregates.