Ionic liquids (ILs) have attracted increasing interests as promising solvents for effective biomass fractionation. Kamlet and Taft (K-T) devised three general polarity parameters (dipolarity/polarizability (p*), hydrogen bond donor acidity (a), and hydrogen bond basicity (�)), and K-T parameters have been successfully applied to characterize solvent properties and efficiency for dissolving biomass of various ILs. However, limited knowledge is available for computationally predicting the solvent properties of ILs and correlating these properties with cellulose solvation and lignin depolymerization. In this work, Density functional theory (DFT) based quantum chemical reactivity descriptors were used to develop structure-property-(re)activity solvent polarity parameters (a, �, and p*) of ILs. We examined the relationship between the predicted K-T values and experimentally tested KT parameters on a series of imidazolium based and amino acid based ILs. Furthermore, we established correlations between the K-T parameters of ILs and cellulose digestibility and lignin removal during IL pretreatment. For the first time, we demonstrated that DFT based descriptor is a very useful tool for predicting not only the chemical structure-reactivity of the selected ILs but also the nature of interactions of ILs with lignin and cellulose. We also conducted fully-atomistic molecular dynamics (MD) simulations on cellulose solvation and lignin depolymerization in selected ILs. The models developed in this study will guide the targeted design of ILs on solubilizing lignocellulosic biomass and will advance the development of IL pretreatment technologies.

Predicting Kamlet�Taft parameters using quantum chemical descriptors

246th National Meeting (2013)

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