Room-Temperature Degradation of Lignin from Wasted Seed Coats for the Production of Pyrocatechol/Gallol Derivatives

The conversion of lignin, an important sustainable biopolymer, into clearly defined monomer compounds is both a significant and appealing challenge. However, this process configuration normally requires high temperatures, elevated H₂ pressures, and a great amount of solvent used. To address these challenges, this study developed a highly effective catalytic system comprising Lewis-acidic organoboranes [(B(C₆F₅)₃)] and triethylsilane (Et₃SiH) to catalytically depolymerize lignin derived from wasted seed coats (macadamia, camellia, apricot, and walnut) into pyrocatechol/gallol derivatives (yield: 14.6-33.3 wt%) under ambient conditions. The analysis using GC-MS and 2D-NMR spectroscopy revealed that the βO4 bonds within lignin are notably severed after the depolymerization. Reactive screening of different βO4 mimics provides insights into understanding the mechanism of lignin depolymerization in the proposed system. Overall, our results indicated a green and sustainable approach for the production of pyrocatechol/gallol from biomass waste.