Martin Nielsen, Henrik Junge, Anja Kammer and Matthias Beller Angew. Chem. Int. Ed.
Innovation in bulk feedstock synthesis is fairly uncommon and usually modestly incremental. As such, it is rare to find new techniques for the synthesis of common simple molecules in the chemical literature.
Matthias Beller, however, reports a catalytic dehydrogenative bulk synthesis of ethyl acetate from ethanol with several distinct advantages over current production protocols.
Ethyl acetate is usually made in bulk by one of three processes: Fischer esterification of acetic acid with ethanol; Tischenko dimerisation of acetaldehyde; or addition of acetic acid to ethylene. This synthesis builds on the work of Gerard van Koten in applying pincer complexes of iridium and ruthenium in dehydrogenative coupling of alcohols.
The groups most interesting result shows that 50 ppm loading of a PNP/Ru complex with a catalytic quantity of ethoxide (0.6 mol%) can give a 77% yield of ethyl acetate with a turnover number exceeding 15000.
The strength of the method lies in lack of undesired byproducts; only hydrogen gas is evolved, and is itself a desirable feedstock. No hydrogen acceptor species is required. Also, both oxidations occur in the same process, requiring only one feedstock for dimerisation.