“On water” hydroformylation of 1-hexene using Rh/PAA (PAA = polyacrylic acid) as catalyst

Abstract

A new rhodium catalyst, Rh/PAA, obtained by the immobilization of Rh(acac)(CO)₂ on polyacrylic acid (PAA), was successfully applied for the hydroformylation of 1-hexene in a water medium. Spectroscopic analysis evidenced that rhodium in Rh/PAA was chemically bonded to polyacrylic acid and formed a hydrido-carbonyl rhodium compound in reaction with H₂/CO. Excellent results (98% conversion, TOF 1000) were obtained in the “on water” hydroformylation of 1-hexene when Rh/PAA was used together with a hydrophobic phosphine (triphenylphosphine, tri-p-tolylphosphine, or diphenyl(2-methoxyphenyl) phosphine). A similar efficiency was also obtained for a system composed of Rh(acac)(CO)₂ and PPh₃, tested in the same conditions in water.