The Ni(0) carbonly complexes of formula NiLx(CO)4-x (x = 1,2; L = PEt3, PEt2Ph, PEtPh2) were oxidized by atm. O, acidic medium, to Ni(II) phosphine complexes, CO2 and phosphine-oxide. CO2 and phosphine-oxide are the result of 2 independent reactions of Ni(II): one with CO and H2O to produce CO2 and Ni(O), the other, as a side reaction with O2, to give phosphine-oxide. By carrying out the oxidn. of Ni(O) in aq. alc. soln. under CO|O2 mixt. at 0°, the reaction CO + 1/202 → CO2 is catalyzed. Under these conditions in Ni complex catalyst is slowly destroyed by the side reaction; however carrying out the oxidn. with stoichiometric O at -10° and successively the carbonylation at room temp., the catalyst is preserved. A possible mechanism for the catalytic cycle is discussed and evidence is given for the formation of a peroxo-species during the oxidn. in neutral medium.
Carbon monoxide oxidation by molecular oxygen in presence of nickel complexes
VASAPOLLO, Giuseppe
1984-01-01
Abstract
The Ni(0) carbonly complexes of formula NiLx(CO)4-x (x = 1,2; L = PEt3, PEt2Ph, PEtPh2) were oxidized by atm. O, acidic medium, to Ni(II) phosphine complexes, CO2 and phosphine-oxide. CO2 and phosphine-oxide are the result of 2 independent reactions of Ni(II): one with CO and H2O to produce CO2 and Ni(O), the other, as a side reaction with O2, to give phosphine-oxide. By carrying out the oxidn. of Ni(O) in aq. alc. soln. under CO|O2 mixt. at 0°, the reaction CO + 1/202 → CO2 is catalyzed. Under these conditions in Ni complex catalyst is slowly destroyed by the side reaction; however carrying out the oxidn. with stoichiometric O at -10° and successively the carbonylation at room temp., the catalyst is preserved. A possible mechanism for the catalytic cycle is discussed and evidence is given for the formation of a peroxo-species during the oxidn. in neutral medium.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
