Chapter 10: Chromium-based Catalysts

Sustainable chemical and energy utilisation is an innovative practice in chemical synthesis, catalyst development and development of reactions for organic transformations. Researchers strive to incorporate sustainable concepts into their work to generate a more economically and environmentally friendly catalyst or chemical reaction. As of late, chromium-based catalysts have been proven to be efficient in several chemical processes, such as polymerisations, oxidations, Diels–Alder reactions, Cannizzaro reactions and Nozaki–Hiyama–Kishi reactions. The advantage of using chromium lies within its chemical nature that allows it to possess multiple oxidation states, giving many types of chromium catalysts. Whether chromium is being used in a bimetallic catalyst or alone as a monometallic catalyst, it has been heavily studied for decades. Chromium-based catalysts have exhibited excellent selectivity towards the desired product and recyclability for additional use in catalytic cycles. Many of the chromium catalysts are low valent and thus provide low toxicity to the reaction system. Also, researchers have used renewable resources such as carbon dioxide, reduced the use of auxiliary solvents and cocatalysts and developed heterogeneous catalysts for improved product/catalyst separation. This chapter will discuss the many organic reactions that have recently been achieved using chromium-based catalysts.