Molecular mechanism of the transformation of oxidized lignin to N-substituted aromatics.
Org Biomol Chem
; 21(47): 9356-9361, 2023 Dec 06.
Article
em En
| MEDLINE
| ID: mdl-37927135
The cleavage of C-C bonds in oxidized lignin model compounds is a highly effective methodology for achieving lignin depolymerization, as well the generation of N-substituted aromatics. Here, density functional theory calculations were performed to understand the mechanism of the transformation of an oxidized lignin model compound (ligninox) and hydroxylamine hydrochloride to N-substituted aromatics. The reaction was proposed to proceed via an energetically viable mechanism featuring the initial production of HOAc acting as proton bridge. According to our calculations, Z-type oxime is the major intermediate of the reaction, with an energy barrier of 22.9 kcal mol-1, owing to the weak interactions between methoxy and oximino groups being stronger than that of E-type oxime. Additionally, the hydroxy addition is the rate-determining step, with an energy barrier of 27.0 kcal mol-1. Moreover, the huge net energy change of Beckmann and abnormal Beckmann rearrangements is the main overall thermodynamic driving force for producing N-substituted aromatics from oximes. The theoretical results have provided a clear picture of how ligninox transforms into N-substituted aromatics and are expected to provide valuable theoretical guidance for lignin depolymerization.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Org Biomol Chem
Assunto da revista:
BIOQUIMICA
/
QUIMICA
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
China
País de publicação:
Reino Unido