Metal Complex Catalysts with Phosphonic Ester Phosphine Ligands. I. Carbonylation of Methanol by Phosphonic Ester Phosphine Rhodium Complexes

Article abstract of DOI:10.1002/prac.19933350406

The treatment of technically available 2-(chloroethyl)phosphonic acid dimethylester (1) with diphenylphosphine and potassium-tert-butylate affords 2-(diphenylphosphino)ethylphosphonic acid dimethylester (2a) in a simple way. 2a can be used as a hemilabil complex ligand (by phosphine and phosphoryl group).Rhodium complexes of the type (MeO)2P(O)CH2CH2P(Ph)2RhL3 (3) were obtained from 2a and exhibit excellent catalytic properties in the liquid-phase carbonylation of methanol to acetic acid.Studies on other chelat-ligands did not confirm the exceptional increase of the activity by bisphosphinemonoxyd-ligands and the inhibition of the title reaction by bisphosphine-ligands already published.