Synthesis and catalytic chemistry of two new water-soluble chelating phosphines - Comparison of ionic and nonionic functionalities

Two new water-soluble chelating alkyl phosphines are described. The compounds are prepared by radical addition of allylic substrates to 1,2-bis(phosphino)ethane in methanol. Complexes with the stoichiometry of 1.5:1 diphosphine:rhodium(I) are effective in the hydrogenation of the olefins I-hexene and crotonaldehyde. Catalyst solutions prepared with the ligand DSPrPE were found to be 3 times more active than those prepared with TPPTS (triphenylphosphine trisulfonate) under identical conditions. Several rhodium complexes of the two ligands are described, and the crystal structure of Rh{1,2-bis[(dihydroxypropyl)phosphino]ethane}Cl-2 was determined.