Recent advances in the development of palladium nanocatalysts for sustainable organic transformations

Synthetic organic transformations using large amount of hazardous raw materials, solvents, catalysts and energy as well as producing large amount of chemical waste are vital for the production of a large variety of pharmaceuticals, polymers, agrochemicals, intermediates, and fine chemical products. However, due to the increasing concern on the environmental problems and the obvious adverse effects of global warming in the world, all chemical industries using uneco-friendly organic transformations are required to make revolutionary changes in their manufacturing processes to make them greener and more sustainable. To develop organic transformation strategies possessing the objectives of sustainable and green chemistry, catalysis is a key technology. Palladium (Pd) has been a popular choice as a catalyst for various chemical reactions owing to its superior activity, selectivity and stability under different reaction conditions, but it is the second most expensive metal nowadays with a rapid increase in its price in last years. In this regard, the use of Pd nanocatalysts instead of unrecyclable homogeneous Pd complexes in the industrially important organic transformations is advantageous in terms of the development of more sustainable transformations. In this review, we highlight the Pd nanocatalysts that have been used in the development of sustainable organic transformations including transfer hydrogenation, C-H bond activation, and C-C coupling reactions (Sonogashira, Suzuki-Miyaura, and Mizoroki-Heck) in the last five years. We focused on examples outlining the principles of sustainable chemistry and a framework to describe greener organic transformations.