Three‐Component Cascade Reaction in a Tube: In Situ Synthesis of Pd Nanoparticles Supported on mpg‐C 3 N 4 , Dehydrogenation of Ammonia Borane and Hydrogenation of Nitroarenes

We report herein a facile in situ synthesis of Pd nanoparticles (NPs) supported on mesoporous graphitic carbon nitride (mpg‐C 3 N 4 /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) in situ generation of Pd NPs supported on mpg‐C 3 N 4 via reduction of mpg‐C 3 N 4 /Pd(II) nanocomposites by AB, (ii) the mpg‐C 3 N 4 /Pd catalyzed dehydrogenation of AB and (iii) the transfer hydrogenation of nitro groups through the mpg‐C 3 N 4 /Pd catalyst. The scope of the mpg‐C 3 N 4 /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 1–2 min with the yields up to 99 % under ambient conditions. It was also shown that the mpg‐C 3 N 4 /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‐C 3 N 4 /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‐C 3 N 4 /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 .