91-10-1Relevant articles and documents
Wildenhain,Henseke
, p. 479 (1969)
One-Pot Transformation of Lignin and Lignin Model Compounds into Benzimidazoles
Guo, Tao,He, Jianghua,Liu, Tianwei,Zhang, Yuetao
supporting information, (2022/02/07)
It is a challenging task to simultaneously achieve selective depolymerization and valorization of lignin due to their complex structure and relatively stable bonds. We herein report an efficient depolymerization strategy that employs 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant/catalyst to selectively convert different oxidized lignin models to a wide variety of 2-phenylbenzimidazole-based compounds in up to 94 % yields, by reacting with o-phenylenediamines with varied substituents. This method could take full advantage of both Cβ and/or Cγ atom in lignin structure to furnish the desirable products instead of forming byproducts, thus exhibiting high atom economy. Furthermore, this strategy can effectively transform both the oxidized hardwood (birch) and softwood (pine) lignin into the corresponding degradation products in up to 45 wt% and 30 wt%, respectively. Through a “one-pot” process, we have successfully realized the oxidation/depolymerization/valorization of natural birch lignin at the same time and produced the benzimidazole derivatives in up to 67 wt% total yields.
Sustainable Production of Benzylamines from Lignin
Guo, Tenglong,Kühn, Fritz E.,Li, Changzhi,Liu, Yuxuan,Wang, Chao,Xiao, Jianliang,Zhang, Bo,Zhang, Tao,Zhao, Zongbao K.
supporting information, p. 20666 - 20671 (2021/08/25)
Catalytic conversion of lignin into heteroatom functionalized chemicals is of great importance to bring the biorefinery concept into reality. Herein, a new strategy was designed for direct transformation of lignin β-O-4 model compounds into benzylamines and phenols in moderate to excellent yields in the presence of organic amines. The transformation involves dehydrogenation of Cα?OH, hydrogenolysis of the Cβ?O bond and reductive amination in the presence of Pd/C catalyst. Experimental data suggest that the dehydrogenation reaction proceeds over the other two reactions and secondary amines serve as both reducing agents and amine sources in the transformation. Moreover, the concept of “lignin to benzylamines” was demonstrated by a two-step process. This work represents a first example of synthesis of benzylamines from lignin, thus providing a new opportunity for the sustainable synthesis of benzylamines from renewable biomass, and expanding the products pool of biomass conversion to meet future biorefinery demands.
Electro-reductive Fragmentation of Oxidized Lignin Models
Yang, Cheng,Magallanes, Gabriel,Maldonado, Stephen,Stephenson, Corey R. J.
, p. 15927 - 15934 (2021/06/30)
Lignin provides a potential sustainable source for production of electron-rich aromatic compounds. Recently, electrochemical lignin degradation via an oxidation/reduction sequence under mild conditions has garnered much attention within the lignin community, as electrochemistry simplifies redox reactions and offers an electron source/sink for synthesis without using stoichiometric oxidants or reductants. This paper describes a fundamental approach for the electrochemical fragmentation of the primary connection in native lignin, β-O-4. Potential-controlled electrolysis enables selective reduction and provides fragmentation products and/or coupling products in isolated yields of 59-92%.