DOI: 10.1021/ja206230h (free Supporting Information) Abstract A (bpy)Cu I/TEMPO catalyst system enables an efficient and selective aerobic oxidation of a broad range of primary alcohols, including allylic, benzylic, and aliphatic derivatives, to the corresponding aldehydes using readily available reagents, at room temperature with ambient air as the oxidant.
Combined ultrahigh vacuum electrochemistry is applied to study the effect of sulfur on copper oxidation in aqueous solution.
It results in the phase transformations of the obtained copper (I) oxide and boehmite during the storing in solution.
Phase composition, pore structure characteristics and morphology of the products are considered.
On the S‐free copper surface, oxide covers the surface almost immediately after the pulse.
On the S‐modified copper surface, oxide growth continues for ∼70 s after the pulse.
Copper does not react with water, but it slowly reacts with atmospheric oxygen, forming a layer of brown-black copper oxide.
In contrast to the oxidation of iron by wet air, this oxide layer stops further, bulk corrosion.
Green, non-toxic oxidizing agents have proven hard to come by.
The cycle is proposed to involve hydrogen transfer to the TEMPO nitrogen atom via a 6-membered transition state, which is far more energetically favorable than the alternative hydrogen transfer to the oxygen atom.