II- from ecological recycling of Pd to greener sonogashira cross-coupling reactions
Résumé
Based on a new process derived from biosorption technology that uses roots from aquatic and wetland plants (Mentha aquatica, Eichhornia crassipes, Pistia stratiotes, Ludwigia peploides, Fallopia japonica), materials rich in lignin (pinecone, bark pine) and wastes rich in tannins (coffee grounds), we were able to prepare a new class of ecocatalyst, called Eco-Pd. The formed Eco-Pd are characterized via MP-AES and XRDP in the order to elucidate the chemical composition and the structure of the new formed materials. Interestingly, the presence of higher-oxidation-state palladium species, namely K2PdCl6, is observed. We describe the use of this new generation of Eco-Pd for a green and sustainable Sonogashira reaction. The absence of copper, ligands, additives, a lower Pd loading (0.05 mol% - 0.1 mol%), the use of green solvents (glycerol/n-BuOH), and the use of biosourced Pd and base (Eco-Ca), are significant advantages of this approach. The combination TON/TOF (103/250 h−1) can be advantageously compared with literature and demonstrates the remarkable practical utility of these new catalysts. Most importantly, the Eco-Pd can be easily recycled by biosorption and reused, that is another asset in terms of sustainable Chemistry.
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