Molecular simulations inform biomass dissolution in ionic liquids in pursuit of benign solvent-system design

Abstract

When we look for a poster child of green chemistry ‘in action’, we do not need to look further than the deconstruction of lignocellulose using ionic liquids (IL) to valorize this renewable resource into useful chemicals. However, there is a caveat: successful development of new chemistries cannot be achieved without systems-based design tools that consider performance in conjunction with potential toxicity. Here, we show that a combination of computational approaches, based on quantum mechanics (QM) calculations and Monte Carlo (MC) simulations, can be leveraged to construct a useful framework for screening existing and designing new ILs capable of safe and selective dissolution of lignocellulosic biomass. With the overwhelming number of IL cation–anion combinations, in silico methods are uniquely suited for this challenge so long as they retain mechanistic relevance to the underlying processes. Our computational approach ensures this criterion by relying on well-correlated linear models of interaction energetics between IL and key biomass building blocks. Functional considerations are supplemented with frontier molecular orbital calculations to determine safety toward aquatic species based on previously established and broadly validated guidelines.