Affiliation:
1. Institute of Chemistry University of Graz Heinchstrasse 28 A-8010 Graz Austria
2. Stratingh Institute for Chemistry University of Groningen Nijenborgh 4 9747 AG Groningen, Groningen The Netherlands
3. Center for Continuous Flow Synthesis and Processing (CCFLOW) Research Center Pharmaceutical Engineering GmbH (RCPE) Inffeldgasse 13 A-8010 Graz Austria
Abstract
AbstractThe development of environmentally friendly methods for the valorization of important phenolic platform chemicals originating directly from lignin‐first depolymerization into value‐added N‐chemicals, such as aniline derivatives, is of high industrial interest. In this work, we tackle this challenging transformation by the judicious combination of electrochemical conversion and chemical functionalization steps. In the first step, lignin‐derived para‐substituted guaiacols and syringols undergo an atom‐efficient, room‐temperature anodic oxidation using methanol both as solvent and reagent towards the formation of the corresponding cyclohexadienone derivatives, which are subsequently converted to synthetically challenging ortho‐methoxy substituted anilines by reaction with ethyl glycinate hydrochloride under mild conditions. The developed method was applied to crude lignin depolymerization bio‐oils, derived from reductive catalytic fractionation (RCF) mediated either by copper‐doped porous metal oxide (Cu20PMO) or Ru/C, allowing the selective production of 4‐propanol‐2‐methoxyaniline (1Gb) and 4‐propyl‐2‐methoxyaniline (2Gb), respectively, from pine lignocellulose. Finally, the application of 2Gb was further studied in the synthesis of carbazole 2Gc, a lignin‐derived analogue of biologically active alkaloid murrayafoline A.
Funder
European Research Council
Subject
General Energy,General Materials Science,General Chemical Engineering,Environmental Chemistry