Premium
Depolymerization of Lignin into Monophenolics by Ferrous/Persulfate Reagent under Mild Conditions
Author(s) -
Bao Hanxi,
Sagues William J.,
Wang Yigui,
Peng Wenbo,
Zhang Lin,
Yang Shunchang,
Xiao Dequan,
Tong Zhaohui
Publication year - 2020
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.202002240
Subject(s) - depolymerization , chemistry , persulfate , reagent , lignin , radical , ferrous , bond cleavage , gel permeation chromatography , organic chemistry , reaction mechanism , yield (engineering) , photochemistry , inorganic chemistry , catalysis , polymer , materials science , metallurgy
This study aimed to use a persulfate together with transition metal ions as the reagent to effectively depolymerize lignin into monophenolic compounds under mild conditions (ambient pressure, temperature <100 °C). The Box‐Behnken experimental design in combination with the response surface methodology was applied to obtain optimized reaction conditions. The results showed that this reagent could depolymerize up to 99 % of lignin dimers to mainly veratraldehyde. This reaction also successfully depolymerized industrial lignins with a high yield of phenolic oils and monophenolic compounds. Quantum chemistry calculations using the density functional theory level indicated that the persulfate free radical attacks C β to break the β‐O‐4 bond of lignin through a five‐membered ring mechanism. This mechanism using persulfate free radicals has a lower activation barrier than that using hydroxyl radicals. Gel permeation chromatography and 2D‐NMR spectroscopy demonstrated the effective cleavage of the β‐O‐4 bonds of lignin after depolymerization.