Imidazolium‐Based Ionic Liquids as Efficient Reagents for the C−O Bond Cleavage of Lignin
Les liquides ioniques de type imidazolium : réactifs efficaces pour la rupture des liaisons C−O dans les lignines
Abstract
Lignin chemical demethylation in ionic liquids was investigated using pure lignin-model monomers and dimer together with dioxan isolated lignins from poplar, miscanthus and maize. Different methylimidazolium ionic liquids (ILs) were compared, according to two different heating processes, microwave irradiation or conventional heating in sealed tube. The conversion yield and influence of the treatments on lignin structure were assessed by 31 P NMR, size exclusion chromatography and thioacidolysis. The acidic IL [HMIM][Br] was shown to be an effective combination solvent/reagent for the demethylation and even depolymerisation of lignin. The relatively mild reaction conditions, the clean work-up, and the ability to reuse the ionic liquid made the described procedure an attractive and new green method for the lignin conversion to produce phenol-rich lignin oligomers.
Domains
Polymers| Origin | Files produced by the author(s) |
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