A fundamental understanding of lignin solubilization offers structural information that would benefit a variety of value added applications. Small angle neutron scattering (SANS) and nuclear magnetic resonance (NMR) spectroscopy were used to study correlations between the functional groups/substructures and solution structures of lignin in DMSO-d₆ and 0.1 N NaOD. Three types of alkaline lignins (Sigma-Aldrich kraft lignin, poplar wood kraft lignin, and corncob soda lignin), exhibiting different degrees of aggregation in 0.4 wt% solutions, were investigated to identify the major intermolecular interactions that cause lignin aggregation. Intermolecular hydrogen bonding, non-covalent π–π interactions between phenyl rings, lignin chain conformation and the degree of branching were discussed. Different operating forces for lignin solubilization and aggregation were found in DMSO-d₆ and NaOD solutions.

C-lignin is a homo-biopolymer, being made up of caffeyl alcohol exclusively. There is significant interest in developing efficient and selective catalyst for depolymerization of C-lignin, as it represents an ideal feedstock for producing catechol derivatives. Here we report an atomically dispersed Ru catalyst, which can serve as an efficient catalyst for the hydrogenolysis of C-lignin via the cleavage of C−O bonds in benzodioxane linkages, giving catechols in high yields with TONs up to 345. A unique selectivity to propenylcatechol (77%) is obtained, which is otherwise hard to achieve, because this catalyst is capable of hydrogenolysis rather than hydrogenation. This catalyst also demonstrates good reusability in C-lignin depolymerization. Detailed investigations by model compounds concluded that the pathways involving dehydration and/or dehydrogenation reactions are incompatible routes; we deduced that caffeyl alcohol generated via concurrent C−O bonds cleavage of benzodioxane unit may act as an intermediate in the C-lignin hydrogenolysis. Current demonstration validates that atomically dispersed metals can not only catalyze small molecules reactions, but also drive the transformation of abundant and renewable biopolymer.