Gold catalysts for the liquid phase oxidation of o- hydroxybenzyl alcohol

Gold on iron oxide catalysts have been investigated in the liquid phase oxidation of o-hydroxybenzylalcohol (salicylic alcohol) under mild conditions. The presence of gold strongly enhances the catalytic activity of iron ox idc, which is practically inactive under the same reaction conditions. The liquid phase oxidation of salicylic alcohol follows a first order reaction rate law with respect to the organic substrate. The order of reaction with respect to the oxygen partial pressure is close to zero. The catalytic activity increases with the gold loading. The oxidation of salicylic alcohol on the catalysts with low gold lending leads to the formation of salicylic aldehyde as the main reaction product. A small amount of salicylic acid was also obtained. On the catalysts: with higher gold loading a progressive decrease of the yield to salycilic aldehyde with the conversion level occurs. When the reaction is carried out using benzene as solvent, the salycilic aldehyde is the end products on all the catalysts investigated regardless of the Sold content. (C) 2001 Elsevier Science B.V. All rights reserved.