Copper is a low-cost plasmonic metal. Efficient photocatalysts of copper nanoparticles on graphene support are successfully developed for controllably catalyzing the coupling reactions of aromatic nitro compounds to the corresponding azoxy or azo compounds under visible-light irradiation. The coupling of nitrobenzene produces azoxybenzene with a yield of 90 % at 60 °C, but azobenzene with a yield of 96 % at 90 °C. When irradiated with natural sunlight (mean light intensity of 0.044 W cm−2) at about 35 °C, 70 % of the nitrobenzene is converted and 57 % of the product is azobenzene. The electrons of the copper nanoparticles gain the energy of the incident light through a localized surface plasmon resonance effect and photoexcitation of the bound electrons. The excited energetic electrons at the surface of the copper nanoparticles facilitate the cleavage of the NO bonds in the aromatic nitro compounds. Hence, the catalyzed coupling reaction can proceed under light irradiation and moderate conditions. This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.

Copper nanoparticles on graphene support: An efficient photocatalyst for coupling of nitroaromatics in visible light

An iridium(I) N-heterocyclic carbene/phosphine complex has been applied to the C-H activation and hydrogen isotope exchange of quinoline N-oxides. The isotope labelling proceeds under exceptionally low catalyst loadings of 0.25 mol%, and delivers products with high levels of deuterium incorporation selectively at the C8 position. A broad substrate scope is demonstrated, with the method tolerant of electron-poor and -rich substrates, and of substitution adjacent to the site of C-H activation. The isotope label is fully retained under standard deoxygenation conditions to give the corresponding labelled quinoline, and the labelling and deoxygenation can be combined in a one-pot procedure.

Cuijiao Ye

Papers

SO2F2-mediated oxidation of primary and tertiary amines with 30% aqueous H2O2 solution

Synthesis of Diazo Compounds Employing NaN3 and Inexpensive SO2F2