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The in situ prepared complex based on copper(II) sulfate and 1,10-phenanthroline (phen) and its performance in the catalytic oxidation of veratryl alcohol (3,4-dimethoxybenzyl alcohol) to veratraldehyde with O 2 in alkaline aqueous solutions have been studied. In aqueous solution, the structure of Cu-phen complexes varies with reaction conditions; by changing either the copper-to-ligand molar ratio or the pH, the amount of coordinated 1,10-phenanthroline and hydroxido ligands in the coordination sphere of copper can be altered in a controlled manner. The highest activities are achieved in the pH range 12.6-13.3, which correlates with the presence of the [Cu(phen)(OH) 2 ] species according to

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Modeled turnover frequencies for varying temperature and total pressure combined with reaction rate controlling regions.

A simple and efficient parallel screening method to evaluate the catalytic activities of homogeneous copper complexes for the oxidation of benzylic alcohols in aqueous solutions with molecular oxygen is reported. Copper(II) sulfate was treated in situ with 22 nitrogen donor ligands, and the catalytic activities of these combinations were studied at four different pH values with two substrates (benzyl alcohol and 3,4-dimethoxy benzyl alcohol (veratryl alcohol)), resulting in 176 oxidation experiments in the primary screening stage. Copper complexes based on N,N,N',N'-tetramethyl ethylenediamine (TMEDA), 9,10-diaminephenanthrene (DAPHEN), and 1,2-diaminocyclohexane (DACH) were determined to be the most active catalysts. In the second screenings, the influence of reaction conditions on Cu(DACH)-, Cu(TMEDA)-, and Cu(DAPHEN)-catalyzed reactions were investigated in more detail. It was found that highly basic reaction conditions favor the reaction with the exception of Cu(TMEDA), which is active at a lower pH range. Under optimized conditions, Cu(DAPHEN) catalyzes the transformation of veratryl alcohol to the corresponding aldehyde with 100% conversion.