Comparison of hydrogenolysis with thioacidolysis for lignin structural analysis

Abstract

Mild hydrogenolysis has been compared with thioacidolysis as a method for degrading lignins in situ and in isolated form before analysis by gas chromato graphy/ mass spectrometry and quantitative 31 P nuclear magnetic resonance (NMR) spectroscopy. Both degradation methods gave similar levels of β-aryl ether-linked phenylpropane units that were released as monomers. Degradation by hydrogenolysis generally gave lower levels of total phenylpropane units when analyzed by 31 P NMR, especially in the case of lignins with high levels of condensed units. Overall, these results indicate that mild hydrogenolysis could offer an alternative to thioacidolysis for probing lignin structure.

Syringyl lignin production in conifers: Proof of concept in a Pine tracheary element system

“…Pyrolysis-GC/MS revealed approximately twofold higher S/G ratios (0.15–0.18) compared with those determined by 2D-NMR (0.06–0.09). Such differences are not surprising as NMR measures the S/G of the entire lignin polymer whereas pyrolysis-GC/MS preferentially cleaves and analyzes monomers released from noncondensed interunit linkages in the lignin polymer that are more abundant in S than G lignin units, resulting in an overestimation ( 38 ).…”

Recent Research Progress on Lignin-Derived Resins for Natural Fiber Composite Applications

“…In contrast, the second degradation occurred at 425-650 • C due to breaking the aromatic moiety's C-C bond [71]. Van de Pas et al [72] have introduced the bio-based lignin epoxy resin monomer, prepared by reacting epichlorohydrin with wood, followed by wood's hydrogenolysis in the presence of Pd/C [73,74]. The blend of hydrogenolysis epoxy prepolymer (LHEP) and oligomer lignin hydrogenolysis epoxy pre-polymer (LHOEP) with bisphenol A diglycidyl ether (BADGE) was prepared using curing agents, namely, isophorone diamine (IPDA) and DETA.…”

Comparison of the Structural Characteristics of Cellulolytic Enzyme Lignin Preparations Isolated from Wheat Straw Stem and Leaf

“…Alternatively, cellulolytic enzyme lignin (CEL) has commonly been used for the structural analysis of cell wall lignin, which utilizes cellulolytic enzyme hydrolysis prior to dioxane/water extraction of ball-milled wood meal to remove carbohydrates and achieve lignin with high yield and purity. , For decades, a lot of work was devoted to understanding the structural features of lignin from a plant cell wall; for example, the monomeric content of lignin polymer and some other structural features were analyzed with different chemical degradation methods such as alkaline nitrobenzene oxidation, ozonation, thioacidolysis, and derivatization followed by reductive cleavage that uses acetyl bromide for derivatization and zinc for reductive cleavage . These wet chemical methods can be very precise for specific functional groups and structural moieties.…”