Selective homogeneous hydrogenation of alk-1-enes using hydridocarbonyltris(triphenylphosphine)rhodium(I) as catalyst

Abstract

The complex hydridocarbonyltris(triphenylphosphine)rhodium(I), RhH(CO)(PPh₃)₃, has been shown to be an efficient catalyst for the homogeneous hydrogenation of unsaturated compounds of the formula RCHCH₂. For hex-1-ene and dec-1-ene in benzene solution, the rate law has been found to be: Rate =k₁K₁c[S][A]/(1 +K₁[S]) where [S] and [A] are the concentrations of alk-1-ene and catalyst respectively, c is the concentration of hydrogen in solution, K₁ is the formation constant for an alkene intermediate complex, and k₁ is the rate constant for the rate determining, hydrogen activation step. The high selectivity for the reduction of alk-1-ene is attributed to steric factors caused by the bulky triphenylphosphine groups.