Mild aerobic oxidation of benzyl alcohols to benzaldehydes in water catalyzed by aqua-soluble multicopper(II) triethanolaminate compounds

The aqua-soluble multinuclear copper(II) compounds [Cu2(μ-H2tea)2{μ3-Na2(H2O)4}(μ6-pma)]n·10nH2O (1) and [O ⊂ Cu4(tea)4(BOH)4][BF4]2 (2) (H3tea = triethanolamine, H4pma = pyromellitic acid) have been applied as efficient catalysts for the mild, selective and clean oxidation of benzyl alcohols to benzaldehydes, which proceeds in sole water as solvent at 50 °C, under atmospheric pressure of air (or O2) as oxidant, and is mediated by TEMPO radical. Molar yields of benzaldehydes (based on alcohol) up to 99% have been achieved (with a high selectivity). Attractive features of these catalytic systems include the use of organic-solvent-free reaction medium, air or dioxygen as oxidant, and aqua-soluble copper catalysts that are readily available by self-assembly.

Aqua-soluble multicopper(II) compounds are shown to act as efficient catalysts for the mild and selective oxidation of benzyl alcohols to benzaldehydes (up to 99% yield), which is mediated by TEMPO radical and does not require the conventional use of any organic solvent or an ionic liquid, proceeding in sole water at 50 °C under atmospheric pressure of air as oxidant.Figure optionsDownload as PowerPoint slide