Metallkomplexkatalysatoren mit Phosphons�ureester-Phosphan-Liganden. I. Carbonylierung von Methanol mit Phosphons�ureester-Phosphan-Rhodiumkomplexen in der Fl�ssigphase

Abstract

Metal Complex Catalysts with Phosphonic Ester Phosphine Ligands. I. Carbonylation of Methanol by Phosphonic Ester Phosphine Rhodium Complexes The treatment of technically available 2‐(chloroethyl)phosphonic acid dimethylester (1) with diphenylphosphine and potassium‐tert.‐butylate affords 2‐(diphenylphosphino)ethylphosphonic acid dimethylester (2a) in a simple way. 2a can be used as a hemilabil complex ligand (by phosphine and phosphoryl group.) Rhodium complexes of the type (MeO)2P(O)CH2CH2P(Ph)2RhL3 (3) were obtained from 2a and exhibit excellent catalytic properties in the liquid‐phase carbonylation of methanol to acetic acid. Studies on other chelat‐ligands did not confirm the exceptional increase of the activity by bisphosphinemonoxyd‐ligands and the inhibition of the title reaction by bisphosphine‐ligands already published.

Synthesis and coordination properties of palladium(II) and platinum(II) complexes with phosphonated triphenylphosphine derivatives

“…Such supported catalysts have been successfully tested in Rhcatalysed alkene hydroformylation [12,14], Rh-catalysed methanol carbonylation [9,15], Ru-catalysed asymmetric b-keto ester hydrogenation [4,11] or Heck reaction [13]. Several tests were also performed in organic solvents under homogeneous conditions (e.g., Pt/Sn-catalysed alkene hydroformylation [11], Rh-catalysed methanol carbonylation [16] and Rh-catalysed styrene hydroformylation [17]). …”

“…Ambitions to use various ''field-proven'' homogeneous catalysts under aqueous and biphasic conditions made for the synthesis of a vast amount of phosphines modified by hydrophilic groups such as ammonium and phosphonium (cationic), sulfonate, phosphonate and carboxylate (anionic) or alcohol and polyether chain (neutral) [1]. Phosphines modified by phosphonate moiety [2] have been attracting attention as alternatives to well-established sulfonates [1]; several examples of their use in biphasic catalysis have been mentioned in literature [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] (e.g., Pd-catalysed electrochemical reduction of CO 2 [3], Rh-catalysed carbon-carbon double bond hydrogenation or hydroformylation [4,5], Pd-catalysed benzyl halide carbonylation [6] and Suzuki coupling [7]). A great advantage (compared with other hydrophilic moieties) is the possibility to bind the phosphonated ligand to an inert oxide surface (e.g., Al 2 O 3 ) [8], onto activated carbon surface [9] or into a layered framework, e.g., zirconium phosphonate [10,12] or zirconium phosphite/phosphonate hybrid material [13].…”

Hemilabile Phosphonate−Phosphane−Rh Catalysts for Homogeneous and Heterogeneous Carbonylation

“…Particle size fractions between 0.3 and 0.8 mm were used for the preparation of support catalysts. The preparation and characterization of the phosphonate−phosphane ligands 1a − d and their rhodium complexes 2a − d and 3a − c (Figure ) are described elsewhere. , …”

“…The preparation and characterization of the phosphonatephosphane ligands 1a-d and their rhodium complexes 2a-d and 3a-c (Figure 2) are described elsewhere. 11,12 Supported catalysts for vapor-phase carbonylations were prepared by impregnation of activated carbon and silica with 2a, 2b, [ClRh(cod)] 2 (cod…”

“…Rhodium complexes with phosphonate−phosphanes appeared as promising catalyst precursors because they form hemilabile complexes, which should enhance the necessary formation of free coordination sites in Rh I intermediates by ring opening of chelate structures and facilitate the generation of the more oxophilic Rh III intermediates by O,P-chelate formation (Figure ). The concept of hemilabile catalysts with chelate structures involved in rate-determining steps implies that the distance and structure between the phosphane and the phosphonate group should affect the carbonylation activity.…”