A further step to sustainable palladium catalyzed oxidation: Allylic oxidation of alkenes in green solvents

• Published in: Applied catalysis. A, General General, 2021-09, Vol.625, p.118349, Article 118349
• Main Authors: dos Santos Costa, Maíra, de Camargo Faria, Amanda, Mota, Rayssa L.V., Gusevskaya, Elena V.
• Format: Article
• Language: English
• Subjects: Acetic acid; Alkenes; Alkenes, allylic oxidation; Benzoquinone; Catalysts; Green solvents; Molecular oxygen; Oxidation; Oxygen; Palladium; Propylene; Selectivity; Solvents; Substrates; Sustainability
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2021.118349

The palladium catalyzed oxidation of alkenes with molecular oxygen is a synthetically important reaction which employs palladium catalysts in solution; therefore, a solvent plays a critical role for the process. In this study, we have tested several green solvents as a reaction medium for the allylic oxidation of a series of alkenes. Dimethylcarbonate, methyl isobutyl ketone, and propylene carbonate, solvents with impressive sustainability ranks and very scarcely exploited in palladium catalyzed oxidations, were proved to be excellent alternatives for the solvents conventionally employed in these processes, such as acetic acid. Palladium acetate alone or in the combination with p-benzoquinone efficiently operates as the catalyst for the oxidation of alkenes by dioxygen under 5–10 atm. For most substrates, the systems in green solvents showed better selectivity for allylic oxidation products as compared to pure acetic acid; moreover, the reactions in propylene carbonate solutions occurred even faster than in acetic acid. [Display omitted] •The palladium catalyzed oxidation of alkenes is an industrially important reaction.•Several green solvents are proposed for the aerobic allylic oxidation of alkenes.•Palladium acetate alone or together with p-benzoquinone operates as the catalyst.•Proposed solvents: dimethylcarbonate, methyl isobutyl ketone and propylene carbonate.•Highly recommended solvents regarding both sustainability and catalyst performance.