Insights into\nthe Role of Deep Eutectic Solvents in\nSorbitol Dehydration: A Combined Experimental and Molecular Dynamics\nStudy

Dehydration of sorbitol catalyzed\nby inorganic acids\nhas been regarded\nas an efficient way to produce isosorbide, which shows application\nin the manufacture of various high value-added compounds. However,\nthese catalysts can cause equipment corrosion and are not recyclable.\nAs a cheap and environmentally friendly catalyst with special tunability\nand stability, a deep eutectic solvent (DES) composed of <i>p</i>-toluenesulfonic acid (<i>p</i>-TSA) and choline chloride\n(ChCl) has emerged to meet the demand for “green production”\nof isosorbide. The conditions for the dehydration of sorbitol catalyzed\nby DESs were systematically investigated. The differences in catalytic\nefficiency stemming from the structural diversity of DESs were explored\nby FT-IR characterization and molecular dynamics simulation. The results\nshowed that isosorbide exhibited notable selectivity (88%) within\nthe DESs (<i>p</i>-TSA:ChCl = 1.2), and achieved a high\nextraction rate (83%) under the synergistic effect of ethyl acetate\nand acetone (4:1). MD simulations indicated that hydrogen bonding\nwas the dominant factor influencing the catalytic activity. The theoretical\nunderstanding of the <i>p</i>-TSA/ChCl structure may provide\na reference for the tunability of novel DESs to meet the requirements\nof catalysis, absorption, and extraction.