Controlling lignin solubility and hydrogenolysis selectivity by acetal-mediated functionalization

Existing lignocellulosic biomass fractionation processes produce lignin with random, interunit C-C bonds that inhibit its depolymerization and constrain its use. Here, we exploit the aldehyde stabilization of lignin to tailor its structure, functionality, and resulting properties, expanding its potential uses. We use bifunctional aldehydes to install specific functionality in lignin and thereby control its physical properties. Rational selection of the aldehyde allows for the formation of acetal-stabilised lignins that are soluble in either polar or non-polar solvents such as water and toluene. Exploiting these novel solubility properties, the effect of solvent on lignin hydrogenolysis is elucidated through the hydrogenolysis of select lignins. Through this study, we notably demonstrate the hydrogenolysis of sodium glyoxylate stabilised lignin in water, opening new avenues for the development of green chemical processes.