A comparative study of the ruthenium(VI)dioxocarboxylato salts, [PPh4][RuO2(OCOR)Cl2] (R = CH3, CF3, C6H5, C6F5, C5H11), in the oxidation of alcohols

The compounds [PPh4][Ru(O)2(OCOR)Cl2] (R = CH31a, CF31b, C6H51c, C6F51d, C5H111e) were prepared and fully characterised. The fluorinated compounds 1b and 1d were obtained in significantly higher yields than their protonated analogues 1a and 1c and compound 1b was found to be a clearly superior stoichiometric oxidant to compound 1a. The compounds 1a–1e were examined as catalytic oxidants for the oxidation of 1- and 2-hexanol, to hexanal and 2-hexanone respectively, with the co-oxidants H2O2, NaOCl, t-BuOOH, N-methylmorpholine-N-oxide, Me3NO, O2, C6H5IO and Bu4NIO4. Compounds 1c and 1d were further studied in the catalytic oxidation of a wide range of alcohols (using N-methylmorpholine-N-oxide and Bu4NIO4 as co-oxidants) and found to give the corresponding aldehydes or ketones very selectively, with no attack on sensitive linkages or functional groups and no over-oxidation products. Compounds 1c and 1d were also supported on poly(4-vinylpyridine) to give active catalysts.

Graphical abstractThe compounds [PPh4][Ru(O)2(OCOR)Cl2] (R = CH31a, CF31b, C6H51c, C6F51d, C5H111e) were prepared and fully characterised. They were compared in the selective stoichiometric and catalytic oxidation of a number of alcohols to their corresponding carbonyl compounds, with a wide range of co-oxidants.Figure optionsDownload full-size imageDownload as PowerPoint slide