Proposed Mechanism for the High-Yield Polymerization of Oxyethyl Propiolates with Rh Complex Catalyst Using the Density Functional Theory Method

In this study, poly(oxyethyl propiolate)s (POP)s featuring various oxyethylene derivatives are synthesized using a [Rh(norbornadiene)Cl](2) catalyst. In particular, POPs featuring the normal oxyethylene chain in the side-chain exhibit excellent yields and high molecular weights in methanol and N,N-dimethylformamide at 40 °C, compared with poly(n-alkyl propiolate)s (PnAP)s. The high reactivity of the oxyethyl propiolate (OP) monomers is clarified by considering the time dependences of the polymerization yields of OPs and alkyl propiolates (Aps). Furthermore, the monomer structure and intermediate conformation of the Rh complex are optimized using Density Function theory (DFT) methods (B3LYP/6-31G** and B3LYP/LANL2DZ) and a polymerization mechanism is proposed.