(501b) Reactivity of Biopolymers in Ionic Liquids

Ionic liquids are gaining increasing acceptance as novel solvents for chemical transformations. This has included a recent focus on the use of ionic liquids for the separation of biopolymers (lignin and cellulose). During this process, the biopolymers are susceptible to multiple types of interactions with the ionic solvent, which can lead to depolymerisation (fragmentation or cleavage reactions), solvolysis or solvent addition reactions.

Our recently proposed Ionosolv process focusses on the use of highly acidic ionic liquids for biomass pretreatment. During pretreatment, all biopolymers in solution (lignin, cellulose, hemicelluloses) are subjected to harsh chemical consitions (non-aqueous, highly acidic, moderate temperature) which can induce novel reactivities. This paper will explore several potential reactions of the ionic liquid solvents with these biopolymers, including ether and ester cleavage and anion-induced substitution reactions. A variety of chemical characterisation techniques have been explored to ensure both a qualitative and quantitative measure of this reactivity.

We have also utilised a series of model compounds (esters, ethers and alcohols) to explore the reactivity of individual polymer subunits with the solvent under a variety of consitions. This portion focusses on electronic effects of the substrate and explores reaction kinetics and changes in mechanism with different functional groups.