Upon exposure to commercial bleach (approximately 5% aqueous sodium hypochlorite), nickel(II) chloride or nickel(II) acetate is transformed quantitatively into an insoluble nickel species, nickel oxide hydroxide. This material consists of high surface area nanoparticles (ca. 4 nm) and is a useful heterogeneous catalyst for the oxidation of many organic compounds. The oxidation of primary alcohols to carboxylic acids, secondary alcohols to ketones, aldehydes to carboxylic acids, and alpha, beta-unsaturated carboxylic acids to epoxy acids is demonstrated using 2.5 mol % of nickel catalyst and commercial bleach as the terminal oxidant. We demonstrate the controlled and selective oxidation of several organic substrates using this system affording 70-95% isolated yields and 90-100% purity. In most cases, the oxidations can be performed without an organic solvent, making this approach attractive as a "greener" alternative to conventional oxidations.

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Oxidation O 0212An Efficient and Practical System for the Catalytic Oxidation of Alcohols, Aldehydes, and α,β-Unsaturated Carboxylic Acids. -In the presence of commercial bleach and NiCl2 or Ni(O-Ac)2, primary and secondary alcohols as well as aldehydes and α,β-unsaturated carboxylic acids undergo oxidation to carboxylic acids, ketones, and epoxy acids, respectively. However, staring from acrylic acid and 3-butenoic acid the expected epoxy acids are not obtained. Acrylic acid provides the chloroacetic acids (XV) and (XVI) and 3-butenoic acid gives fumaric acid. -(GRILL, J. M.; OGLE, J. W.; MILLER*, S. A.; J. Org. Chem. 71 (2006) 25, 9291-9296; Dep. Chem., Tex. A&M Univ., College Station, TX 77843, USA; Eng.) -Jannicke 16-036