title: A novel dicationic phenoxaphosphino-modified Xantphos-type ligand: a ligand for highly active and selective, biphasic, rhodium catalysed hydroformylation in ionic liquids.
abstract: A highly active and regioselective catalyst obtained from a novel dicationic ligand (1) and Rh(CO)2(acac) for hydroformylation of 1-hexene and 1-octene in ionic liquids is reported. Optimisation studies of various reaction parameters led to an unprecedentedly active (TOFs > 6200 mol mol(-1) h(-1), T= 100 degrees C), selective (l/b ratios > 40) and stable hydroformylation procedure. No catalyst leaching (Rh-loss < 0.07% of initial rhodium intake, P-loss < 0.4% of the initial phosphorus intake) or losses in performance could be measured during 1-octene hydroformylation recycle experiments in 1-butyl-3-methylimidazolium hexafluorophosphate. At low catalyst loadings activities and regioselectivities competitive with one-phase catalysis in conventional solvents were observed. At high catalyst loadings the system is extremely stable and has a long shelf-life as a result of the formation of stable, if inactive rhodium dimers.
authors.affiliation: van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands.
authors.forename: Raymond P J
authors.initials: RP
authors.lastname: Bronger
authors.forename: Silvana M
authors.initials: SM
authors.lastname: Silva
authors.forename: Paul C J
authors.initials: PC
authors.lastname: Kamer
authors.forename: Piet W N M
authors.initials: PW
authors.lastname: van Leeuwen