Probing the Regiochemistry of Acrylate Catalytic Insertion Polymerization via Cyclocopolymerization of Allyl Acrylate and Ethylene

When palladium phosphine sulfonate catalysts were used, ethylene and ally! acrylate were copolymerized. The copolymer structure was analyzed by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) and was found to contain both delta-valerolactone and gamma-butyrolactones inserted within the chain. These cyclic structures were determined to be the outcome of 1,2 allyl insertions and 2,1 acrylate insertions except when the acrylate was cyclopolymerized: in this case, regiochemistry of the insertion was 1,2. This first example of cyclopolymerization with Pd phosphine suffonate catalysts outlines the extraordinary versatility of this family of compounds and paves the way to new polyolefins containing complex repeat units built in.