Lignin is an encrusting material that makes up part of the wood matrix. Because there are many hydroxy groups present in the lignin molecule, potential aromatic aldehydes that could be useful precursors for agrochemicals or other fine chemicals could be made available upon oxidation or oxidative cracking.
Narayan Hosmane, Northern Illinois University, USA, and colleagues explore the use of ionic liquid (IL)-stabilized metal nanoparticles for the efficient, robust, and recyclable oxidation of benzyl alcohols and lignin for the production of aromatic aldehydes. The use of IL-stabilized metal nanoparticles as catalysts should overcome the solubility limitation of lignin and favor its oxidative conversion. They use a pyridinium salt of iron bis(dicarbollide) as cocatalyst and oxygen gas as oxidant. To explore this system, a variety of substituted benzyl alcohols were used as substrates.
The optimized reaction conditions were applied to lignin, and a conversion of 72 % was achieved. Moreover, the recovered catalyst could be used in three subsequent reactions with only minor reduction in lignin conversion. Detailed studies and further exploration of this approach are ongoing.
- An Efficient and Recyclable Catalytic System Comprising Nanopalladium(0) and a Pyridinium Salt of Iron Bis(dicarbollide) for Oxidation of Substituted Benzyl Alcohol and Lignin,
Y. Zhu, L. Chuanzhao, M. Sudarmadji, N. Hui Min, A. Oh Biying, J. A. Maguire, N. S. Hosmane,
ChemistryOpen 2012, 1(2), 67–70.