Steric effects in palladium catalyzed CO/ethene copolymerization

ORGN 648

Maria Caporali, m.caporali@tue.nl, Christian Mueller, c.mueller@tue.nl, Dieter Vogt, d.vogt@tue.nl, and Piet W.N. M. van Leeuwen, pwnm@science.uva.nl. Chemical Engineering, Eindhoven University of Technology, Den Dolech 2, Eindhoven, 5600 MB, Netherlands
The palladium catalyzed methoxycarbonylation of ethene is a reaction of great potential from an industrial point of view and has attracted academic interest for many years. Our aim is to investigate the influence of the steric bulk of the diphosphine ligands on the activity and selectivity of the correspondant palladium complex in the copolymerization reaction of CO/ethene. Therefore the synthesis of new bidentate diphosphines containing diphenyl ether backbone and with variable steric bulk on phosphorous atom has been performed. The catalytic experiments show that the product distribution is dramatically different going from the less hindered ligand to the bulkiest one: the former gives only polymers, while the latter gives mainly methyl propanoate and a very small amount of low molecular weight oligomers. A Schulz-Flory distribution was found for the oligomers.