Oxo complexes of ruthenium(VI) and (VII) as organic oxidants

Oxidation of a variety of saturated and unsaturated primary and secondary alcohols by tetraoxoruthen-ate(VI), [RuO4]2–, tetraoxoruthenate(VII), [RuO4]–, barium trans-trioxodihydroxoruthenium(VI), trans-Ba[Ru(OH)2O3], dioxotrichlororuthenate(VI), [RuO2Cl3]–, and dioxodichlorobipyridylruthenate(VI), [RuO2(bipy)Cl2], has been studied; [RuO4]2–may be used catalytically in conjunction with [S2O8]2– under basic aqueous conditions. For some of these systems, the oxidation of several aldehydes and amines were also examined. Both [RuO4]2–and [RuO4]– oxidise primary alcohols to carboxylic acids and secondary alcohols to ketones; the reactivity of these reagents towards unsaturated alcohols was studied in particular. The new species [PPh4][RuO2Cl3] and also [RuO2(bipy)Cl2] cleanly oxidise a wide range of alcohols to aldehydes and ketones without attack of double bonds. Ba[Ru(OH)2O3] functions as a heterogeneous oxidant in dichloromethane, oxidising only the most reactive alcohols to aldehydes.