New one-pot syntheses of ketals and acetals from oleic acid

• A new one-pot synthesis of ketal derivatives from oleic acid is described.
• The oxidant system consists of hydrogen peroxide and a peroxo-tungsten anion supported on resin as catalyst.
• The acetal formation from alcohols is explained by a double oxidation of alkene and alcohol.
• Several ketals were prepared from various reactants also used as solvents.

Ketals derived from unsaturated fatty acids, such as oleic acid (OA), are widely used as intermediates in the synthesis of various polymers, biologically active compounds and other high-value derivatives. We propose the study of new conditions for one-pot syntheses of ketals and acetals from oleic acid, using acetone or different alcohols as both reactant and solvent. OA was oxidized in a batch reactor in the presence of hydrogen peroxide (H2O2, 30%) as an oxidant and a peroxo-tungsten anion supported on resin as the catalyst. We investigated the influence of several parameters of this process, using 9,10-dihydroxyoctadecanoic acid as the target molecule. The best operating conditions resulted in an OA conversion above 80%, with a good yield (60%) obtained for the OA/H2O2/{PO4[WO(O2)2]4}3− system supported on a resin, at 70 °C for 16 h in acetone. The hydroxyl moiety was oxidized, generating the corresponding aldehyde derivative, when alcohols were used as the solvent.