164019-44-7Relevant articles and documents
Indirect formation of carboxylic acids via anhydrides in the palladium-catalyzed hydroxycarbonylation of aromatic halides
Grushin, Vladimir V.,Alper, Howard
, p. 4305 - 4315 (2007/10/02)
The carbonylation of [(Ph3P)2Pd2Ph2(μ-OH)2] (2) in the presence of PhI results in the quantitative formation of benzoic anhydride and [(Ph3P)2Pd2(PhCO)2(μ-I) 2] (3). This transformation contributes to some extent to the production of benzoic acid from haloarenes, CO, and alkali, catalyzed by [(Ph3P)2PdCl2], the latter being converted to 2 under the reaction conditions. Phenyl- and benzoylpalladium benzoates are likely key intermediates in the indirect formation of the acid, via the anhydride, by the carbonylation of 2. One such complex, [L2Pd(Ph)(PhCOO)] (5, L = Cy3P), was isolated from the carbonylation of [(Cy3P)2Pd2Ph2(μ-OH)2] (4) in hexane. The related complexes, [L2Pd2Ph2(μ-PhCOO)2] (6, L = PPh3; 7,L = PCy3), were prepared from benzoic acid and hydroxo complexes 2 and 4, respectively. Treatment of 6 and 7 with the corresponding phosphine afforded [L2Pd(Ph)(PhCOO)] (8, L = PPh3; 5,L = PCy3). When 6-8 were reacted with CO in benzene, benzoic anhydride was readily formed, whereas in the case of 5 both carbonylation and reductive elimination were sluggish. Crystallographic data for 6 (1:2 chloroform solvate): space group Pccn, a = 22.499(4) A?, b = 10.992(3) A?, c = 24.514(6) A?, V = 6062.4(23) A?3, Z = 4, R = 0.056, and Rw = 0.038.
