Homogeneous catalysis in supercritical carbon dioxide with rhodium catalysts tethering fluoroacrylate polymer ligands

Rhodium(I) complexes for homogeneous catalysis in supercritical carbon dioxide, scCO2, have been prepared from the reaction of phosphine containing fluoroacrylate polymeric ligands with [Rh(μ-Cl)(COD)]2. The fluoroacrylate polymer used was prepared via a free radical initiator polymerization reaction from 1H,1H,2H,2H-heptadecafluorodecyl acrylate monomer and N-acryloxysuccinimide, NASI. Diphenylphosphinopropylamine, DPPA, was attached to the copolymer as it replaces the NASI group, thus providing the copolymer a phosphine ligand for coordination. 31P NMR and UV–Vis spectra were used to confirm the coordination of phosphine in the polymer to Rh(I). The synthesized catalysts possess excellent solubility in scCO2. Hydrogenation of 1-octene in scCO2 resulted in conversion (70%) to n-octane within 12 h (reaction conditions 70°C, 172 bar, 1:4000 catalyst/substrate mole ratio).