Catalytic activity of palladium complexes, PdCl2 (COD) and PdCl2(P(OPh)3)2, in methoxycarbonylation of iodobenzene

The methoxycarbonylation of iodobenzene with PdCl2(COD) and PdCl2(P(OPh)(3))(2) (at 40 degreesC, 1 atm of CO, in methanol solution) produced benzoic acid methyl ester with the yield of 14% and 17%, respectively. The low yield of that reaction is caused by partial reduction of palladium to not active palladium black. It was found, that the addition of ammonium salt, (Bu4NCl)-Bu-n prevents palladium reduction to inactive Pd(0) form and increases the activity of the system. In reaction catalyzed by PdCl2(COD) at 40 degreesC and 1 atm of CO in methanol the yield of ester increased from 14% to 52% when (BU4NCl)-B-n was added. The yield of ester equal 96% was obtained with the same catalyst in molten (Bu4NCl)-Bu-n at 80 degreesC and 5 atm of CO. (C) 2003 Elsevier Science B.V. All rights reserved.