Chemistry

Oxidative Flow

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Science  02 Jul 2010:
Vol. 329, Issue 5987, pp. 15
DOI: 10.1126/science.329.5987.15-c

Alcohol oxidation is a common step in the synthesis of pharmaceutical intermediates, and oxygen is in many ways the ideal reagent to induce it. The gas is plentiful and nontoxic, and so is the by-product, water, that it's shuffled into as the reaction ensues. Unfortunately, oxygen also has several serious drawbacks that have largely precluded its use in this context. In too pure a form, it can react violently with solvents and other peripheral organic fragments. At the same time, it is a competing challenge to keep enough of the gas mixed with the liquid reaction medium to inhibit catalyst decomposition. As a result, oxidations still often rely on expensive reagents and generate associated toxic by-products. Ye et al. now present a reactor design that makes substantial progress in surmounting these obstacles. They employ a dilute stream of 8% oxygen in nitrogen, so as to avoid combustion hazards, and they implement a continuously flowing reaction process to optimize mixing. Using several previously reported palladium-based catalysts, they demonstrate high alcohol oxidation yields across a diverse substrate pool on scales ranging from tens of grams to a kilogram.

Green Chem. 12, 10.1039/c0gc00106f (2010).

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