Establishing Lignin Structure-Upgradeability Relationships Using Quantitative 1H-13C Heteronuclear Single Quantum Coherence Nuclear Magnetic Resonance (HSQC-NMR) Spectroscopy

Lignin depolymerization could provide an attractive renewable aromatic feedstock for the chemical industry. Past studies have suggested that lignin structural features such as ether content are correlated to lignin’s upgradeability. An obstacle to the development of a conclusive causal relationship between lignin structure and upgradeability has been the difficulty to quantitatively measure lignin structural features. Here, we demonstrated that a modified HSQC-NMR method known as HSQC0 can accurately quantify lignin functionalities in extracted lignin using several synthetic polymer models. We then prepared a range of isolated lignin samples with a wide range of ether contents (6%-46%). By using a simple ether cleavage model, we were able to predict final depolymerization yields very accurately (