(720i) Multiscale Solvation Effect of Deep Eutectic Solvents on Reactivity of ?-O-4 Bond of Lignin Dimers

Deep eutectic solvents (DES) emerge as a new media for accelerate the depolymerization of lignin. The large number of DESs create a vast space for searching for suitable candidates. However, one open question is how the solvation of DES may affect the reactivity of β-O-4 bond of lignin. To shed light on this subject, we investigate the solvation effect of three DESs on the reactivity of four lignin dimers using molecular dynamics simulations and quantum mechanical calculations. The three DESs are choline: lactic acid (1:2), choline: levulinic acid (1:2) and choline: oxalic acid (1:1). The four lignin dimers are G-G, G-S, S-S and S-G. We investigate the solvation shell and the exposure area and electrostatic potential of β-O-4. The simulation results show multiscale effect of the solvation on the reactivity of β-O-4 bond. The solvation shells of all four lignin dimers are dominated by positively charged molecules in all three DESs. Such accumulation creates a positively charge shell. The β-O-4 bond also present various exposure areas in DESs, as well as its electrostatic potential. Our simulations imply that DES solution can affect the depolymerization of lignin through multiple paths.