title: Understanding the Solubility of Acetaminophen in 1-n-Alkyl-3-methylimidazolium-Based Ionic Liquids Using Molecular Simulation.
abstract: During the manufacturing of pharmaceutical compounds, solvent mixtures are commonly used, where the addition of a cosolvent allows for the tuning of the intermolecular interactions present in the system. Here we demonstrate how a similar effect can be accomplished using a room temperature ionic liquid. The pharmaceutical compound acetaminophen is studied in 21 common ionic liquids composed of a 1-n-alkyl-3-methylimidazolium cation with 1 of 7 anions. Using the acetate anion, we predict a large enhancement in solubility of acetaminophen relative to water. We show how this is caused by a synergistic effect of favorable interactions between the ionic liquid and the phenyl, hydroxyl and amide groups of acetaminophen, demonstrating how the ionic liquid cation and anion may be chosen to preferentially solvate different functional groups of complex pharmaceutical compounds. Additionally, while the use of charge scaling in ionic liquid force fields has previously been found to have a minute effect on ionic liquid structural properties, we find it appreciably affects the computed solvation free energy of acetaminophen, which in turn affects the predicted solubility.
authors.affiliation: Department of Chemical, Paper and Biomedical Engineering, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Paluch
authors.affiliation: Instituto de Química, Universidade Federal Fluminense , Outeiro de São João Batista, s/n CEP: 24020-141, Niterói, RJ, Brazil.
authors.forename: Tuanan C
authors.initials: TC
authors.lastname: Lourenço
authors.affiliation: Department of Chemical, Paper and Biomedical Engineering, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Fenglin
authors.initials: F
authors.lastname: Han
authors.affiliation: Instituto de Química, Universidade Federal Fluminense , Outeiro de São João Batista, s/n CEP: 24020-141, Niterói, RJ, Brazil.
authors.forename: Luciano T
authors.initials: LT
authors.lastname: Costa
mesh_terms: D000082:Acetaminophen / Q000737:chemistry*; D000085:Acetates / Q000737:chemistry; D018712:Analgesics, Non-Narcotic / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D012995:Solubility; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D000085:Acetates; D018712:Analgesics, Non-Narcotic; D007093:Imidazoles; D052578:Ionic Liquids; D014867:Water; D000082:Acetaminophen