RhCl2(Cp*)(monodentate P-ligand)- and trans-PdCl2(monodentate P-ligand)2-type complexes (where the P-ligand is either a P-heterocyclic or a cyclopropane-based tertiary phosphine) have been used as catalyst precursors in hydroformylation and hydroalkoxycarbonylation reactions, respectively. The chemoselectivity of hydroformylation is excellent (higher than 99%) in all cases. A strong dependence of the regioselectivity on the P-substituents was found in the case of the P-heterocyclic ligands. While the P-phenyl substituent favours the formation of the branched aldehyde regioisomer (3-phenyl-propanal), the introduction of ortho- and para-tolyl substituents resulted in the slightly preferred formation of linear aldehyde (2-phenyl-propanal). At the same time, the introduction of tolyl groups instead of the phenyl one caused an unexpectedly high increase in the catalytic activity. An unprecedented feature of the system has been observed by using complexes with cyclopropyl-phosphine ligands. The formation of the linear aldehyde regioisomer (3-phenyl-propanal) is favoured by the decrease of the temperature.
ASJC Scopus subject areas
- Chemical Engineering(all)