(717g) Mechanistic Study of Diaryl Ether Bond Cleavage during Lignin Hydrogenolysis Using Advanced Lignin Model Compounds
- Conference: AIChE Annual Meeting
- Year: 2019
- Proceeding: 2019 AIChE Annual Meeting
- Group: Forest and Plant Bioproducts Division
- Time: Thursday, November 14, 2019 - 5:18pm-5:36pm
As a polymer biosynthesized via the general phenylpropanoid pathway, three monolignols, p-coumaryl alcohol (H), coniferyl alcohol (G), and sinapyl alcohol (S), are involved in lignification. The extra methoxyl, phenol, and sidechain on the aromatic ring dramatically affect the electron distribution and the chemical properties of the substrate. Thus, using proper lignin model compounds is crucial for lignin depolymerization studies; minor changes in the structure of lignin model compounds may have a huge effect on the reaction mechanism. Diaryl ether linkages in lignin, the presence of which was recently confirmed by using appropriate lignin model compounds, are more complicated than simple diphenyl ethers. Thus, it is necessary to examine the reaction mechanism of diaryl ethers in lignin using authentic lignin model compounds under catalytical hydrogenolysis condition.
In this work, a set of lignin model compounds from dimers to tetramers has been subjected to the hydrogenolysis reaction. A set of new meta-substituted aromatic products were first identified by NMR and high-resolution MS. The mechanism of the formation of the rearrangement products and sidechain-truncation products are discussed.