Homogeneous catalysis of olefin isomerisation. Part V. Pent-1-ene isomerisation catalysed by solutions of RuHCl(PPh3)3 and of RuHCl(CO)(PPh3)3; variation of the isomeric composition of pent-2-ene and its attribution to steric factors

Abstract

Isomerisation of pent-1-ene to pent-2-ene in the range 35 to 80 °C is catalysed by solutions of RuHCl(PPh₃)₃ and of RuHCl(CO)(PPh₃)₃ in benzene. Preferential formation of cis-olefin occurs at higher catalyst concentrations, but a change to preferential trans-olefin formation is observed as catalyst concentration is reduced. This change in selectivity, which is not accompanied by a change in mechanism, is attributed to a progressive decongestion of the catalytic site brought about by a gradual increase in the degree of dissociation of the catalyst by loss of triphenylphosphine ligands.