We are pursuing oxidative methods for selective, high-yield conversion of lignin into valuable small molecule products. We recently reported a catalytic method for chemoselective aerobic oxidation of diols,1 and we anticipate that similar methods could be employed to achieve selective oxidation of lignin. Our initial efforts utilize dimeric model compounds (e.g., 1  ) with a �-O-4 linkage to simulate the chemical reactivity expected from authentic samples of lignin. Diverse alcohol oxidation methods have been investigated to establish whether selective oxidation of the primary aliphatic or the secondary benzylic alcohol in 1  could be achieved. Oxidation reactions with traditional chemical oxidants show that TEMPO-based methods enable highly selective oxidation of this substrate. The selectivity for oxidation of the primary aliphatic vs. secondary benzylic alcohol is dependent upon the specific reagent/catalyst and reaction conditions. These results established useful benchmarks for the development of analogous catalytic oxidation methods that use O2as the stoichiometric oxidant. In the best case, exclusive oxidation of the benzylic alcohol is can be achieved in 96% isolated yield. Efforts associated with the development of these methods and their application to selective lignin conversion will be presented.Acknowledgement: This work was funded by the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-FC02-07ER64494).Reference (1) Hoover, J. M.; Stahl, S. S. J. Am. Chem. Soc. 2011  , 133, 16901-16910.

Selective aerobic oxidation methods for lignin conversion to simple aromatic compounds

245th National Meeting (2013)

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