Three-Component Cascade Reaction in a Tube: In Situ Synthesis of Pd Nanoparticles Supported on mpg-C3N4, Dehydrogenation of Ammonia Borane and Hydrogenation of Nitroarenes

We report herein a facile insitu synthesis of Pd nanoparticles (NPs) supported on mesoporous graphitic carbon nitride (mpg-C3N4/Pd) during the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of nitroarenes at room temperature. In the presented protocol, a three-component cascade reaction is realized in a pressure tube at room temperature, encompassing (i) insitu generation of Pd NPs supported on mpg-C3N4 via reduction of mpg-C3N4/Pd(II) nanocomposites by AB, (ii) the mpg-C3N4/Pd catalyzed dehydrogenation of AB and (iii) the transfer hydrogenation of nitro groups through the mpg-C3N4/Pd catalyst. The scope of the mpg-C3N4/Pd catalyzed tandem dehydrogenation of AB and hydrogenation reactions were studied over a wide range of nitroarenes (10 examples), which are all selectively converted to the corresponding anilines within only 1-2min with the yields up to 99% under ambient conditions. It was also shown that the mpg-C3N4/Pd catalysts could be scaled up to large scale production of anilines and reused up to ten times without any significant loss in the yields. Additionally, the mpg-C3N4/Pd catalysts were isolated after the hydrogenation reactions and tested as catalysts in the hydrolysis of AB by studying the detailed reaction kinetics. The isolated mpg-C3N4/Pd nanocatalysts showed a very high performance in hydrogen generation from the hydrolysis of AB by providing an initial turnover frequency (TOF) of 66.3 min(-1).