Finding new energy and raw material sources as alternatives to those currently derived from fossil fuels is one of the principal challenges of the 21st century. Lignocellulose is the most abundant non-food source of biomass and is a very attractive feedstock for the production of renewable fuels and chemicals to supplement those derived from fossil sources.1 This feedstock is composed of hemicellulose, cellulose and lignin; the latter consists largely of methoxyphenyl propanoid subunits, which account for ca. 30% of the total lignocellulosic biomass. However, the development of selective catalytic systems to valorize lignin has been a major problem due to its diverse and robust chemical composition.2 In this work, we describe the selective aerobic oxidation of phenoxyethanol, �-O-4 and �-1 lignin models using oxovanadium(V) catalysts.3,4 The selectivity for the catalytic C-H, C-O and C-C bond cleavage is highly dependent on the phenolic substitution in lignin models (�-O-4 and �-1), the solvent employed, and the pressure of air (as an oxidant). The mechanisms involved in these transformations are also discussed. Preliminary results for the selective C-C bond cleavage in polyalcohols using the tripodal oxovanadium(V) triethoxyamine catalyst are presented. Low catalyst loading and high efficiencies are achieved with this catalyst. Our work with real lignin extracts demonstrates successful depolymerisation of organosolv lignin using oxovanadium(V) catalysts as observed by Gel Permeation Chromatography and Quantitative-Heteronuclear Single Quantum Coherence NMR.(1) Corma, A.; Iborra, S.; Velty, A. Chem. Rev. 2007,  107, 2411.(2) Zakzeski, J.; Bruijnincx, P. C. A.; Jongerius, A. L.; Weckhuysen, B. M. Chem. Rev. 2010,  110, 3552.(3) Sedai, B.; D�az-Urrutia, C.; Baker, R. T.; Wu, R.; Silks, L. A. P.; Hanson, S. K. ACS Catal. 2011,  1, 794.(4) D�az-Urrutia, C.; Sedai, B.; Leckert, K.; Baker, R. T.; Hanson, S. K. Curr. Org. Chem. 2014,  in press.

Selective oxidation of lignin models and extracts using homogeneous oxovanadium(V) catalysts

248th National Meeting (2014)

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