The depolymerization of lignin in lignocellulosic biomass holds promise as an economical and environmentally attractive process for renewable production of aromatic chemicals. However, there are few reliable and atom-economical routes for obtaining small organic molecules from this complex biopolymer. Several different key linkages are present in the polymeric structure of lignin, the most common of which is β-O-4 linkage; for valorization of lignin, efficient cleavage of the C–O bond in this β-O-4 linkage is imperative. This subject therefore naturally commands substantial research attention. Here we describe a class of simple and efficient base metal catalyst for the selective and atom-economical hydrogenolysis of C–O bonds in a variety of lignin β-O-4 models compounds. The homo- and hetero-bimetallic heterogeneous catalysts described, are prepared using a surface organometallic chemistry (SOMC) approach, and are characterized using a suite of surface analysis techniques. The utility and novelty of this method is demonstrated in the highly efficient and selective hydrogenolysis of 2-(2-methoxyphenoxy)-1-phenylethanol, to give guaiacol and acetophenone, over a SOMC fabricated copper catalyst, under mild conditions. Importantly this simple and scalable one-pot procedure requires no reducing agent, or any other stoichiometric additive, reinforcing the overall ‘greenness’ of this approach. Preliminary mechanistic studies are presented, along with the application of this method to actual lignin samples.

Base metal-catalyzed, additive-free C–O bond cleavage of β-O-4 lignin model compounds

2019 Spring National Meeting

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