Neuartige basische Liganden für die homogenkatalytische Methanolcarbonylierung, XI [1]. Ether-Phosphan-Cobalt-Komplexe in der katalytischen Methanolhydrocarbonylierung zu Acetaldehyd / Novel Basic Ligands for the H om ogeneous Catalytic Methanol Carbonylation, XI [1]. Ether Phosphane Cobalt Complexes in the Catalytic Hydrocarbonylation of Methanol to Acetaldehyde

Abstract

Abstract PhP(CH2C4H7O2)2 (1) and [-CH2(Ph)P~D]2 (3a-c) [D = CH2C4H702 (a), CH2C4H7O (b). CH2CH2OCH3 (c)] are obtained by reaction of Li2PPh and Na(Ph)P~D with ClCH2C4H7O2 and C1CH2CH2Cl, respectively. 1 and 3a, b give rise to high selectivities and conversions in the cobalt catalyzed hydrocarbonylation of methanol to acetaldehyde. Model complexes of cobalt which are of importance in the catalytic cycle are synthesized. Complexes of the type X2Co(Ph2P~D)2 (6az, 6bx-bz, 6cx-cz), especially those with X = I, obtained from CoX2 [X = Cl (x), Br (y), I (z)] and the ether phosphanes Ph2P~D (5a-c), are regarded as precursors of the catalytically active species. With K[HB(sec-C4H9)3] they are reduced to the cobalt(I) complexes XCo(Ph2P~D)(Ph2P~D) (7az, 7bx-bz, 7cx-cz). Trapping reactions with CO, PPh3 or 5b, c lead to the compounds XCo(CO)2(Ph2P~D)2 (8az, 8bx-bz, 8cx-cz), XCoPPh3(Ph2P~D)2 (9bx-bz). and XCo(Ph2P~D)3 (10bz, cz), respectively, with cleavage of a Co-O bond. The reduction of X2Co(PPh3)2 (11x, z) with K[HB(sec-C4H9)3] represents a simple method for the preparation of the complexes XCo(CO)2(PPh3)2 (13x, z) which are formed from the intermediates XCo(PPh3)2 · THF (12x, z) in the presence of CO.