Oxidative decarboxylation of cyclohexanecarboxylic acid

Abstract

Cyclohexanecarboxylic acid is converted to a mixture of cyclohexanone and cyclohexene by reacting it at temperatures around 200" with an oxygen-containing gas and steam in the presence of metal-salt catalysts.In investigations of novel syntheses of cyclohexanone we found that cyclohexanecarboxylic acid can be oxidized in the liquid phase at temperatures around 200" to cyclohexanone, cyclohexene and a small amount of phenol by using a mixture of air and water as oxidizing agents and metal salts (e.g. those of copper and magnesium) as catalysts.The reaction was so carried out that the lower boiling products (phenol, cyclohexanone and cyclohexene) were distilled off continuously during the reaction, while the higher boiling by-products and the unconverted cyclohexanecarboxylic acid remained as much as possible in the heated reaction zone.The over-all reactions leading to cyclohexanone and cyclohexene are given in equations (1) and (2), respectively. COOH 0 COOH The phenol is presumably formed by dehydrogenation to benzoic acid and subsequent oxidation of the latter as described previously 11