Oxidação de olefinas por peróxido de hidrogênio catalisadas por paládio (II)

Abstract

In this work, a catalytic system for oxidation of olefins, -bisabolol, linalool, nerol, citronelol, citronelal and adoxal was successfully applied, using a palladium(II) based catalyst. The reactions occurred in the presence of the oxidizer hydrogen peroxide, in acetonitrile as solvent. For the oxidation of -bisabolol, a major product was obtained, with selectivity of up to 99%, resulting from the oxidation of its tri-substituted pair, leading to the entry of a hydroxyl in the tertiary carbon. The oxidation of the substrates linalool and nerol led to the formation of a main product for each, with a maximum selectivity of 75% for the product of linalool and 70% for the product of nerol, in both there was also the entry of a hydroxyl in the tertiary carbon of the triple-substituted double bond. As a result of citronellol oxidation, it was found that the tri-substituted duo undergoes an intramolecular nucleophilic attack, involving the participation of the hydroxyl group and leading to the cyclization of the substrate, forming only one product of interest, an eight-membered cyclic ether, with selectivity of 96 %. The oxidation of citronelal and adoxal, gave rise to a main product for each one, resulting from the oxidation of their trisubstitute pairs, also causing the entry of a hydroxyl in the tertiary carbon of the pair, obtaining selectivity of 98% and 85% respectively. The applied catalytic system proves to be very efficient, with selectivity only for the tri-substituted double bond, keeping the other functions of the oxidized molecules intact, in addition to a good conversion rate. Therefore, the applied catalytic system can be an attractive route for obtaining oxygenated products from compounds of bio-renewable origin