A rare oxidation of camphene to acid and aldehyde in the presence of Lacunar Keggin heteropoly salts

Abstract

In this work, monolacunary Keggin heteropolyacid salts containing sodium as the countercation were synthesized and evaluated as catalysts on the camphene oxidation with hydrogen peroxide. Under reaction conditions (i.e., 333 K, air atmosphere, CH3CN solution), camphene (1) was selectively oxidized by H2O2, generating two rare products; camphene aldehyde (1a) and camphenylic acid (1b), which have attractive olfactive properties. Notably, these uncommon compounds were obtained with the camphene preserving their carbon skeletal. Among the lacunar Keggin heteropolyacid salts, the Na7PW11O39 lacunar salt was the most active and selective toward oxidation products, completely converting the camphene to (1a) and (1b) products. The catalyst load, the oxidant: camphene molar ratio and the reaction temperature allowed to control the (1a)/ (1b) proportion.