282087-76-7Relevant academic research and scientific papers
Mechanistic studies of the hydroformylation of 1-alkenes using a monodentate phosphorus diamide ligand
Van der Slot, Saskia C.,Kamer, Paul C.J.,Van Leeuwen, Piet W.N.M.,Iggo, Jonathan A.,Heaton
, p. 430 - 441 (2001)
The mechanism of the rhodium-catalyzed hydroformylation reaction using a monodentate phosphorus diamide ligand has been investigated. The system presents an ideal case to illustrate the basics of hydroformylation. A detailed kinetic study and (in situ) spectroscopic techniques revealed that several of the elementary reaction steps are involved in the hydroformylation rate control. Which step is rate-determining depends strongly on the conditions used. Deuterioformylation showed that alkene coordination followed by hydride migration is irreversible under the conditions studied. The rhodium hydride complex HRhL2(CO)2 and several rhodium-acyl complexes were observed during the hydroformylation reaction. The structures of the rhodium-acyl complexes have been characterized using 31P, 13C, and 103-Rh NMR spectroscopy. The major rhodium-acyl complex formed, RC(O)RhL2(CO)2, has a trigonal-bipyramidal structure with the two phosphorus ligands coordinated in the equatorial plane. The exchange rates of the equatorial and apical carbonyl ligands with dissolved carbon monoxide differ significantly, the equatorial carbon monoxide being much more labile.
Rhodium complexes based on phosphorus diamide ligands: catalyst structure versus activity and selectivity in the hydroformylation of alkenes
Van Der Slot, Saskia C.
, p. 2504 - 2515 (2008/10/08)
The rhodium-catalyzed hydroformylation reaction of 1-octene with phosphorus diamide ligands has been investigated. Four monodentate phosphorus diamide ligands and six bidentate phosphorus diamide ligands derived from a 1,3,5-trisubstituted biuret structure have been synthesized. These types of ligands combine steric bulk with π-acidity. The rhodium complexes formed under CO/H2 have been characterized by high-pressure spectroscopic techniques. Spectroscopic experiments revealed that the monodentate ligands form mixtures of HRhL2(CO)2 and HRhL(CO)3. The ratio HRhL2(CO)2:HRhL(CO)3 depends on the ligand concentration and its bulkiness. The bidentate ligands form stable, well-defined catalysts with a specified structure under hydroformylation conditions. Both monodentate and bidentate ligands have been tested in the hydroformylation reaction of 1-octene. The monodentate ligands form very active catalysts, but the linear-to-branched ratio of the product is low. The bidentate ligands show improved selectivity compared to the monodentate ligands and an activity that is only slightly lower.
