Degradation of a Lignin Model Compound by ROS Generated In Situ through Controlled ORR in Ionic Liquid

The cleavage of the linkage bonds among the C9 units in lignin molecules via selective oxidation method to obtain small-weight aromatic compounds is an important way to lignin valorisation. In this study, the cleavage pathways of bonds in a lignin model compound, GGE (guaiacylglycerol-β-guaiacyl ether), by the reactive oxygen species (ROS) in situ generated through electrochemical oxygen reduction reaction (ORR) in an aprotic ionic liquid ([BMIM]BF4) was investigated. The results indicated that when the main ROS was ·OOH, coniferyl alcohol, guaiacol and vanillin were detected as the degradation products which is supposed to be caused by β-O-4 bonds cleavage; Otherwise, when HO2− was the main ROS, coniferyl alcohol could not be detected and the degradation reaction is believed to be trigerred by Cα-Cβ bonds cleavage.