791136-95-3Relevant articles and documents
Phenoxaphosphino-modified xantphos-type ligands in the rhodium-catalysed hydroformylation of internal and terminal alkenes
Bronger, Raymond P. J.,Bermon, Jochem P.,Herwig, Juergen,Kamer, Paul C. J.,Van Leeuwen, Piet W. N. M.
, p. 789 - 799 (2007/10/03)
The solubility of the modifying ligand is an important parameter for the efficiency of a rhodium-catalysed hydroformylation system. A facile synthetic procedure for the preparation of well-defined xanthene-type ligands was developed in order to study the influence of alkyl substituents at the 2-, and 7-positions of the 9,9-dimethylxanthene backbone and at the 2-, and 8-positions of the phenoxaphosphino moiety of ligands 1-16 on solubility in toluene and the influence of these substituents on the performance of the ligands in the rhodium-catalysed hydroformylation. An increase in solubility from 2.3 mmol·L-1 to > 495 mmol·L-1 was observed from the least soluble to the most soluble ligand. A solubility of at least 58 mmol·L-1 was estimated to be sufficient for a large-scale application of these ligands in hydroformylation. Highly active and selective catalysts for the rhodium-catalysed hydroformylation of 1-octene and trans-2-octene to nonanal, and for the hydroformylation of 2-pentene to hexanal were obtained by employing these ligands. Average rates of > 1600 (mol aldehyde) x (mol Rh)-1 x h-1 {conditions: p(CO/H 2) = 20 bar, T = 353 K, [Rh] = 1 mM, [alkene] = 637 mM} and excellent regio-selectivities of up to 99% toward the linear product were obtained when 1-octene was used as substrate. For internal olefins average rates of > 145 (mol aldehyde) x (mol Rh)-1 x h-1 {p(CO/ H2) = 3.6-10 bar, T = 393 K, [Rh] = 1 mM, [alkene] = 640-928 mM} and high regio-selectivities up to 91% toward the linear product were obtained.
