Imperial College London

Professor Tom Welton

Faculty of Natural SciencesDepartment of Chemistry

Professor of Sustainable Chemistry



+44 (0)20 7594 5763t.welton Website




601AMolecular Sciences Research HubWhite City Campus






BibTex format

author = {De, Gregorio GF and Weber, CC and Gräsvik, J and Welton, T and Brandt, A and Hallett, JP},
doi = {10.1039/C6GC01295G},
journal = {Green Chemistry},
pages = {5456--5465},
title = {Mechanistic insights into lignin depolymerisation in acidic ionic liquids},
url = {},
volume = {18},
year = {2016}

RIS format (EndNote, RefMan)

AB - Acidic anions of ionic liquids have been demonstrated as efficient catalysts for the cleavage of the β-O-4 ether linkage prevalent in the lignin superstructure. Through the use of lignin model compounds with varying functionality and by monitoring reaction kinetics, a full mechanistic investigation into the hydrolysis of the β-O-4 linkage in acidic ionic liquid solutions is reported. Hammett acidities are reported for different 1-butyl-3-methylimidazolium hydrogen sulfate [C4C1im][HSO4] ionic liquid systems with varying acid and water concentrations and were correlated to substrate reactivity. Results show that the rate of ether cleavage increases with an increase in acidity and the initial dehydration of the model compound is the rate-determining step of the reaction. The Eyring activation parameters of the reaction in hydrogen sulfate ionic liquids with a variety of cations are reported, indicating a consistent E1 dehydration mechanism. Hydrogen bonding in protic ionic liquids was shown to significantly influence anion–cation interactions, consequently altering the solvation of the protonated starting material and therefore the overall rate of reaction. Comparison of reaction rates in these ionic liquids with results within aqueous or aqueous/organic media indicate that the ionic liquids facilitate more rapid cleavage of the β-O-4 ether linkage even under less acidic conditions. All the reported results give a complete overview of both the mechanistic and solvation effects of acidic ionic liquids on lignin model compounds and provide scope for the appropriate selection and design of ionic liquids for lignin processing.
AU - De,Gregorio GF
AU - Weber,CC
AU - Gräsvik,J
AU - Welton,T
AU - Brandt,A
AU - Hallett,JP
DO - 10.1039/C6GC01295G
EP - 5465
PY - 2016///
SN - 1744-1560
SP - 5456
TI - Mechanistic insights into lignin depolymerisation in acidic ionic liquids
T2 - Green Chemistry
UR -
UR -
VL - 18
ER -