Fluoroacrylate Copolymer-Supported Rhodium Catalysts for Hydrogenation Reactions in Supercritical Carbon Dioxide

Abstract

We have attached a homogeneous rhodium catalyst to a fluoroacrylate copolymer backbone, making it soluble in supercritical carbon dioxide. The polymer was synthesized by the polymerization of 1H,1H,2H,2H-heptadecafluorodecyl acrylate monomer (zonyl TAN) (I), available from Dupont, and N-acrylosuccinimide (NASI), the former increasing the solubility in supercritical carbon dioxide and the latter providing attachment sites for the catalyst. Diphenylphosphinopropylamine, NH2(CH2)3PPh2 (DPPA), was used to exchange the NASI groups in the polymer, which was then reacted with [RhCl(COD)]2 to obtain the catalyst. We determined that the catalyst is soluble in supercritical carbon dioxide and evaluated its hydrogenation activity using 1-octene and cyclohexene hydrogenation as model reactions. The synthesis route for the catalyst is reproducible, as shown by reaction activity studies on different batches of catalyst. The catalyst was evaluated at different substrate-to-rhodium molar ratios and at different temperatures. Most reactions were carried out at 173.4 bar.