Synthesis of Aliphatic Polycarbonates from Diphenyl Carbonate and Diols over Zinc (II) Acetylacetonate.

APCs (aliphatic polycarbonates) are one of the most important types of biodegradable polymers and widely used in the fields of solid electrolyte, biological medicine and biodegradable plastics. Zinc-based catalysts have the advantages of being low cost, being non-toxic, having high activity, and having excellent environmental and biological compatibility. Zinc (II) acetylacetonate (Zn(Acac)2) was first reported as a highly effective catalyst for the melt transesterification of biphenyl carbonate with 1,4-butanediol to synthesize poly(1,4-butylene carbonate)(PBC). It was found that the weight-average molecular weight of PBC derived from Zn(Acac)2 could achieve 143,500 g/mol with a yield of 85.6% under suitable reaction conditions. The Lewis acidity and steric hindrance of Zn2+ could obviously affect the catalytic performance of Zn-based catalysts for this reaction. The main reasons for the Zn(Acac)2 catalyst displaying a higher yield and Mw than other zinc-based catalysts should be ascribed to the presence of the interaction between acetylacetone ligand and Zn2+, which can provide this melt transesterification reaction with the appropriate Lewis acidity as well as the steric hindrance.