Renewable Feedstocks from Lignin Dissasembly
Selective disassembly of lignin can provide a renewable, sustainable source of feedstock chemicals. Recently, the stable free radical TEMPO (2,2,6,6-tetramethylpiperdine-N-oxyl) has found use in the depolymerization of lignin. While most TEMPO based systems are limited to primary alcohols, we have discovered that coordination of TEMPO to Lewis acids, such as FeCl3 and AlCl3, generates adducts that can oxidize lignin model compounds within minutes at room temperature. We have also found that these adducts can oxidize 9,10-dihydroanthracene to anthracene, suggesting a substrate scope far beyond lignin may be possible with this protocol. We are currently interested in further expanding the substrate scope of these adducts, as well as investigating the reactivity of TEMPO with Lewis acids of varying strengths in order to understand the mechanism of TEMPO catalyzed oxidations.