Carbonylation of Ethylene Oxide to β-Propiolactone: A Facile Route to Poly(3-hydroxypropionate) and Acrylic Acid

We report an improved synthesis of poly(3-hydroxypropionate) (P3HP) from ethylene oxide (EO) and carbon monoxide (CO) through the intermediate beta-propiolactone (PL). The optimized carbonylation of EO resulted in high selectivity for PL using a bimetallic [Lewis acid](+)[Co(CO)(4)](-) catalyst. Anionic ring-opening polymerization of PL by organic ionic compounds to afford P3HP was also investigated. A phosphazenium carboxylate initiator displays the highest activity for the polymerization and produces polyesters with molecular weights over 100 kDa and narrow molar mass distributions. Furthermore, the known rearrangement of PL and the thermolysis of P3HP provide efficient EO-based routes to the important commodity chemical acrylic acid.