Akademik Veri Yönetim Sistemi
28th National Chemistry Congress (with International Participation), Mersin, Türkiye, 15 - 21 Ağustos 2016
The reduction of unsaturated groups is one of the indispensable tools in organic chemistry for the synthesis of wide array of new and valuable organic compounds [1]. Although various reduction methods have been developed so far, the hydrogenation by H2 gas is still widely-used one both in industry and research laboratories. This type of reduction reactions is generally performed in the presence of a nobel metal catalyst under high H2(g) pressure at high temperature in organic solvents [2]. Therefore, a great effort has been dedicated to develop a more facile and generalized route for the hydrogenation of unsaturated organic groups. The transfer hydrogenation is considered to be one of the most promising and green alternative. Up to date, a variety of molecules such as isopropanol and hydrazine have been tested as hydrogen donor in the transfer hydrogenation of unsaturated organic compounds, but they were slow and provided low selectivity. Recently, we have developed a very promising yet efficient transfer hydrogenation route using ammonia borane (AB, NH3·BH3) as a hydrogen source and reduced graphene oxide supported Ni30Pd70 alloy nanoparticles (rGO-Ni30Pd70) as catalysts [3]. In our one-pot methodology, rGO-Ni30Pd70 catalyzes AB dehydrogenation and then in-situ transfer the H2(g) to the unsaturated group in aqueous methanol solution in a thermolysis tube at room temperature.
In this study, we report the application of our new transfer hydrogenation methodology over aromatic nitro, nitrile, and carbonyl compounds to the corresponding primary amines and alcohols, respectively, in the presence of rGO-CoPd catalysts under ambient conditions. Our reduction approach comprises the tandem AB dehydrogenation and hydrogenation of unsaturated organic groups catalyzed by reduced graphene oxide supported Co30Pd70 alloy nanoparticles (rGO-Co30Pd70) in water/methanol mixture (v/v = 7/3) at room temperature. Monodisperse Co30Pd70 alloy NPs were synthesized by using an organic solution phase protocol involving the co-reduction of cobalt(II) acetylacetonate and palladium(II) acetylacetonate in oleylamine and borane-tert-butylamine mixture at 100 oC. The colloidal Co30Pd70 NPs were assembled on reduced graphene oxide (rGO-Co30Pd70) before their use as catalysts in the tandem reactions. A variety of aromatic nitro, nitriles, and carbonyl compounds were tested by the rGO-Co30Pd70 catalyzed tandem reaction and all the corresponding primary amines or alcohols were obtained by the yields reaching up to 99% within reaction times of 5–15 min.