Neuartige basische Liganden fuer die homogenkatalytische Methanolcarbonylierung XXIX. Kieselgelfixierte (Ether-Phosphan)Rhodium-Komplexe in der katalytischen Hydrocarbonylierung von Methylacetat zu Ethylidendiacetat

Article abstract of DOI:10.1016/0022-328X(90)85518-4

The heterogenized (ether-phosphane)rhodium complexes <-O(CH3)2-Si(CH2)3P(R)D>2Rh(CO)Cl (2a-d) are obtained from the silica anchored silylalkyl(ether-phosphanes) 1a-d and (μ-CIRh(CO)2>2.The palladium complex <-O(CH3)2Si(CH2)3PPh2>2PdCl2 (4) is formed by addition of (COD)PdCl2 to the heterogenized alkyldiphenylphosphane <-O(CH3)2-Si(CH2)3PPh2> (3).High pressure experiments provide information on conversion and selectivity in the hydrocarbonylation of methylacetate to ethylidenediacetate, if parameters like pressure, temperature, ether moieties in the ligands 1a-d, and composition of catalyst and synthesis gas are varied.To investigate the influence of temperature and pressure on the leaching of metals, the supported catalysts are recovered and re-used. trans-(P<*>O)2Rh(CO)Cl (7e) is formed in homogeneous phase by reaction of <μ-IRh(CO)2>2 (5) with the ligand 6e O = Me3Si(CH2)3P(Ph)CH2CH2OCH3>.Oxidative addition of CH3I to 7e affords trans-(P<*>O)2Rh(CO)(CH3)(I)2 (9e).In the presence of CO methyl migration in 9e leads to trans-(P<*>O)2Rh(CO)(COCH3)(I)2 (10e).Reductive elimination of CH3C(O)I from 10e regenerates 7e, probably via the cationic intermediate O)-(<*>P O)Rh(CO)COCH3)I> (8e).The unstable cationic (ether-phosphane)rhodium complex O)(<*>P O)Rh(CO)COCH3)I> (11e) which is isostructural to 8e is obtained by I^- abstraction from 10e.