Hydroformylation with a rhodium/bulky phosphite modified catalyst. A comparison of the catlyst behaviour for oct-1-ene, cyclohexene and styrene van Rooy, A.; Kamer, P.C.J.; van Leeuwen, P.W.N.M. Published in: Organometallics DOI:10.1021/om00001a010Link to publication Citation for published version (APA):van Rooy, A., Kamer, P. C. J., & van Leeuwen, P. W. N. M. (1995). Hydroformylation with a rhodium/bulky phosphite modified catalyst. A comparison of the catlyst behaviour for oct-1-ene, cyclohexene and styrene. Organometallics, 14, 34. DOI: 10.1021/om00001a010 General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. The rhodium-catalyzed hydroformylation of oct-1-ene, cyclohexene, and styrene has been studied using Rh( C0)Acac as the catalyst precursor and tris(2-tert-butyl-4-methylphenyl) phosphite as the ligand (2' = 40-100 "C, PCO = 2.5-44 bar, PHZ = 2.5-50 bar, toluene as a solvent). For oct-1-ene, very high hydroformylation rates are obtained (39.8 x lo3 mol [mol Rhl-l h-l) under mild conditions (PCO = 10 bar, PHZ = 10 bar, T = 80 "C). The concentration dependencies of the reaction rate show that the rate-determining step is the reaction of HZ with the acylrhodium complex. A negative order in the CO concentration is observed. For cyclohexene, the reaction rate is lower under the same conditions (512 mol [mol Rhl-I h-l, [cyclohexene] = 0.91 M), the addition of cyclohexene to the starting rhodium hydride complex now being rate-limiting. In the hydroformylation of styrene, the rate is 3 times lower than that of oct-1-ene. For the formation of the linear 3-phenylpropanal, the rate-determining step is the reaction of Hz with the rhodium acyl species. CO inhibits the reaction. In contrast with the formation of the secondary 2-octyl species from oct-1-ene, the formation of the secondary (1-phenylethy1)rhodium species is reversible. For the formation of the branched aldehyde, the kinetics depend strongly on the CO partial pressure. At low CO pressures, addition of CO to the proposed (y3-l-phenylethyl)rhodium intermediate is slow. At higher CO pressures, hydrogenolysis of the rhodium acyl intermediate is the rate-determining step and the rate decreases with increasing CO. IntroductionMuch research has been conducted to elucidate the mechanism and the kinetics of the rhodium-ca...

The rhodium-catalyzed hydroformylation with the diphosphites P[O(2,2‘-(4-X-6-Y-C6H2)2O][O(2,2‘-(4-X-6-Y-C6H2)2)OP][O(4-Z-C6H4]2 (X = Y = tert-butyl, Z = H (1), Z = OMe (2), Z = C6H5 (3), Z = Cl (4); X = OMe, Y = tert-butyl, Z = H (5)), [PO(2,2‘-(4,6-(tert-C4H9)2C6H2)2)O]2R [R = O(CH2)2O (6), R = O(CH2)3O (7)], [PO(2,2‘-(C6H4)2)O]2R, R = O(2,2‘-(4-MeO-6-tert-C4H9C6H2)2O (8), R = O(2,2‘(4,6-tert-C4H9)2C6H2)2O (9)], and [PO(2,2‘-(4,6-(tert-C4H9)2C6H2)2)O]2[O(2,2‘-(C6H4)2)O] (10) as ligands is studied with oct-1-ene and styrene as substrates. For oct-1-ene the highest normal to branched ratio obtained is 48 (5). For styrene the product selectivity depends strongly on the reaction temperature; a branched to normal ratio of 19 is found for 7 when T = 40 °C vs a branched to normal ratio of 0.19 for 1 when T = 120 °C. A bulky and bisequatorially (ee) coordinating diphosphite is required to obtain a high regioselectivity for linear aldehydes, while flexible diphosphites or equatorially−axially (ea) coordinating diphosphites lead to an enhancement of the formation of branched aldehydes. The hydroformylation of oct-1-ene has a first-order dependency in the oct-1-ene concentration, the order in CO is approximately −0.65, and the order in H2 is approximately 0.2. This is consistent with a kinetic scheme in which alkene addition is the rate-determining step. The crystal structures of RhAcac(4) and RhH(CO)2(4) (11), are presented. The hydrido ligand in 11 could not be located. The structure reveals a distorted TBP with 4 ee coordinated, the P(1)−Rh−P(2) angle being 115.95(9)°. The distortion is indicative of a crowded rhodium center which explains the obtained high linearity of the hydroformylation products.

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A rhodium complex containing tris(o-tert-butyl-p-methylphenyl) phosphite as a ligand catalyses the hydroformylation of oct-1-ene with good selectivity and extremely high rates; the rate constant, which is pseudo first-order in [H2] and l/[CO], shows that the reaction of hydrogen is the rate determining step.