Efficient demethylation of aromatic methyl ethers with HCl in water

Abstract

A green, efficient and cheap demethylation reaction of aromatic methyl ethers with mineral acid (HCl or H2SO4) as catalyst in high temperature pressurized water provided the corresponding aromatic alcohols (phenols,...

Low molecular weight and highly functional RCF lignin products as a full bisphenol a replacer in bio-based epoxy resins

“…Interestingly, given the excellent solubility of RCF lignin, no addition of a co-solvent was necessary which is often the case for lignin glycidylation. 4,7 1 H- 13 C HSQC analysis confirmed introduction of the oxirane moiety on the aromatic part of the lignin structure (Figure S16-S17). The number of oxirane moieties is expressed as the epoxy content (in mmol g -1 ) or the epoxy equivalent weight (EEW; g eq -1 ).…”

“…7,8 This is in stark contrast with the low molecular weight RCF lignin wherein the lignin fraction is composed of highly functional monomers and low Mw oligomers. 5,9 These monomers can be selectively extracted and utilized towards various commodity and specialty chemicals (phenol and propylene production 10 , less toxic bisphenols 11 , terephthalic acid 12 , catechol 13 and pharmaceutical compounds 14,15 ), allowing access to the lignin fractions with low Mw oligomers, high functionality and low Đ (Figure S2A-C). Few groups recently used the RCF lignin oligomers in proof-of-concept application development.…”

“…a. Centre for Sustainable Catalysis and Engineering, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium * corresponding author: e-mail: bert.sels@kuleuven.be Electronic Supplementary Information (ESI) available: [Detailed experimental procedures, Supplementary notes on RCF, separations and 1 H- 13 C HSQC spectroscopy, additional GPC chromatograms, 1 H-NMR spectra, 31 P-NMR spectra, 1 H- 13 C HSQC spectra and additional figures and tables can be found in the supporting information. ].…”

“…4 As reported in Figure S7 for P1 and Figure S8 for F1-4, many lignin inter-unit linkages and end-units resulting from the reactions during RCF can be detected by 1 H-13 C HSQC spectroscopy. Hydrogenolysis of most of the native lignin ether linkages and their selective conversion to RCF analogues is proven by 1 H- 13 C HSQC spectroscopy (Supplementary note 3), In addition, aliphatic end-units -the hydrogenolysis products -are found to a much higher extent (Supplementary note 3). This is in accordance with a recent study on Pd/C-catalyzed RCF.…”

One-pot production of phenazine from lignin-derived catechol

“…27–30 Hydrolyzing the methoxy group in lignin-derived guaiacyl monomers also produces catechols. 31,32 Compared with phenolic monomers, the upgrading of catechyl monomers has been less studied. Currently, the main strategy of conversion is to oxidatively open the ring to produce dicarboxylic acids, such as muconic acid 33,34 as well as C3 and C4 dicarboxylic acids if strong oxidation conditions are applied.…”