Grirrane Abdessamad, Corma Avelino, García Hermenegildo
Instituto de Tecnología Química, Consejo Superior de Investigaciones (CSIC), Universidad Politécnica de Valencia, 46022-Valencia, Spain.
Science. 2008 Dec 12;322(5908):1661-4. doi: 10.1126/science.1166401.
The selective formation of aromatic azo compounds at preparative or industrial levels requires stoichiometric amounts of environmentally unfriendly transition metals or nitrites. Here, we show that gold nanoparticles supported on titanium dioxide (TiO2) and nanoparticulated cerium dioxide (CeO2) catalyze the aerobic oxidation of aromatic anilines to aromatic azo compounds with yields above 98% under mild reaction conditions. Gold on TiO2 can also act as a reductive catalyst to access the compound directly from nitroaromatics through a two-step, one-pot reaction. The catalytic process shows promise for efficient synthesis of symmetric aromatic azo compounds, and even a range of asymmetric aromatic azo compounds.
在制备或工业规模上选择性地形成芳香族偶氮化合物需要化学计量的对环境不友好的过渡金属或亚硝酸盐。在此，我们表明负载在二氧化钛（TiO₂）和纳米二氧化铈（CeO₂）上的金纳米颗粒在温和的反应条件下催化芳香族苯胺的需氧氧化生成芳香族偶氮化合物，产率高于98%。负载在TiO₂上的金还可以作为还原催化剂，通过两步一锅法反应直接从硝基芳烃获得该化合物。该催化过程为对称芳香族偶氮化合物甚至一系列不对称芳香族偶氮化合物的高效合成带来了希望。
