Immobilized palladium nanoparticles on Schiff base functionalized ZnAl layered double hydroxide: A highly stable and retrievable heterogeneous nanocatalyst towards aryl halide cyanations

In this study, a new nanocatalyst system with economical, environmental, moisture, and air-stable features was developed through immobilization of Pd nanoparticles (Pd NPs) on Schiff base-functionalized Zn-Al layered double hydroxide (ZnAl LDH-Sch). The system was named as Pd NPs@ZnAl LDH-Sch, and its structure was fully authenticated with several techniques. The catalytic potential of Pd NPs@ZnAl LDH-Sch nanocatalyst was then evaluated in the aryl halide cyanations for the fabrication of various benzonitriles using K4[Fe(CN)6]. These tests indicated that Pd NPs@ZnAl LDH-Sch nanocatalyst is tolerant against various functional groups, and the desired benzonitrile products were acquired with good to high yields within 2 h. The hot filtration experiment revealed that Pd NPs@ZnAl LDH-Sch acts heterogeneously in the reactions. Because of its heterogeneous manner, Pd NPs@ZnAl LDH-Sch was readily recovered via simple filtration and reused up to 11 successive runs by protecting its stability/durability. Moreover, it was found that the synthesized Pd NPs@ZnAl LDH-Sch nanocatalyst shows a performance in the aryl halide cyanations better than other reported catalysts.