Abstract

Copper-Catalyzed Continuous-Flow Transfer Hydrogenation In Ethylene Glycol

Katia Martina, Associate Professor of Organic Chemistry, Università degli Studi di Torino

Conventional protocols are increasingly being replaced by new efficient synthetic processes that use safer chemicals, naturally abundant solvents, atom economy and efficient catalytic systems to yield the desired product with sustainability, scalability and high chemical efficiency. Flow approaches have been demonstrated to show great merit in safety and speed, as well as in their increased yields and quality. Given the importance of this process in both industry and academia, it is not surprising that a vast number of catalytic flow-chemistry hydrogenation protocols have been reported over the last decade with noble metals and that reductions of nitro benzene to aniline and alkyne to alkenes are largely studied. Non-noble metals have also been of great interest to the scientific community due to their economic and environmental advantages. The preparation of a robust supported catalyst that is made up of copper nanoparticles on celite for the selective transfer hydrogenation under continuous flow of nitroarenes and alkynes will be presented. The method is efficient and environmentally benign thanks to the absence of hydrogen gas and precious metals. Long-term stability studies show that the catalytic system is able to achieve very high conversion (> 99%) when working for long time. The versatility of the transfer hydrogenation system has been tested using representative examples with moderate-to-excellent yields being obtained.