Dramatic Change in Viscosities of Pure Ionic Liquids upon Addition of Molecular Solvents

Viscosities of binary mixtures of pyridinium based ionic liquids (1-butyl pyridinium tetrafluoroborate, [BP][BF4], 1-butyl 3-methyl pyridinium tetrafluoroborate [3-MBP][BF4], 1-butyl 4-methyl pyridinium tetrafluoroborate, [4-MBP][BF4]), and phosphonium based ionic liquids, (tetrabutyl phosphonium alaninate, [TBP][Ala]; tetrabutyl phosphonium valinate, [TBP][Val]) with the molecular solvents, water, methanol and dichloromethane, have been measured at 298.15 K. A Brookfield ultra-rheometer was employed to measure the reported viscosities. The drop in viscosity in the close vicinity of pure ionic liquid is more prominent in polar solvents like water compared to less polar solvents. The temperature dependence of this observation was also studied for binary mixtures of [4-MBP][BF4] with water in range of 298.15–323.15 K. The Vogel-Fulcher-Tamman (VFT) equation was employed to investigate the temperature dependence of the viscosities of pure pyridinium-based ionic liquids in the temperature range from 298.15–323.15 K.

[1]  K. Seddon,et al.  Viscosity and Density of 1-Alkyl-3-methylimidazolium Ionic Liquids , 2002 .

[2]  R. Ludwig,et al.  The association of water in ionic liquids: a reliable measure of polarity. , 2006, Angewandte Chemie.

[3]  T. Vandernoot,et al.  Temperature dependence of viscosity for room temperature ionic liquids , 2004 .

[4]  Kenneth R. Seddon,et al.  Ionic liquids. Green solvents for the future , 2000 .

[5]  Ashok Kumar.  Surface tension, viscosity, vapor pressure, density, and sound velocity for a system miscible continuously from a pure fused electrolyte to a nonaqueous liquid with a low dielectric constant : anisole with tetra-n-butylammonium picrate , 1993 .

[6]  Mingfang Yu,et al.  The Physical Properties of Aqueous Solutions of the Ionic Liquid [BMIM][BF4] , 2006 .

[7]  A. Mele,et al.  The Structure of a Room‐Temperature Ionic Liquid with and without Trace Amounts of Water: The Role of CH⋅⋅⋅O and CH⋅⋅⋅F Interactions in 1‐n‐Butyl‐3‐Methylimidazolium Tetrafluoroborate , 2003 .

[8]  K. Seddon,et al.  Influence of chloride, water, and organic solvents on the physical properties of ionic liquids , 2000 .

[9]  M. Grätzel,et al.  Hydrophobic, Highly Conductive Ambient-Temperature Molten Salts. , 1996, Inorganic chemistry.

[10]  Tom Welton,et al.  Room-temperature ionic liquids: solvents for synthesis and catalysis. 2. , 1999, Chemical reviews.

[11]  J. Brennecke,et al.  Recovery of Organic Products from Ionic Liquids Using Supercritical Carbon Dioxide , 2001 .

[12]  Peter Wasserscheid,et al.  Ionic Liquids in Synthesis , 2002 .

[13]  Anilesh Kumar,et al.  Diels-Alder reactions are faster in water than in ionic liquids at room temperature. , 2006, Angewandte Chemie.

[14]  H. Ohno,et al.  Effect of tetrabutylphosphonium cation on the physico-chemical properties of amino-acid ionic liquids. , 2006, Chemical communications.

[15]  J. Troncoso,et al.  Viscosities for Ionic Liquid Binary Mixtures with a Common Ion , 2008 .

[16]  I. Abdulagatov,et al.  Viscosity of aqueous calcium chloride solutions at high temperatures and high pressures , 2006 .

[17]  G. Voth,et al.  Unique spatial heterogeneity in ionic liquids. , 2005, Journal of the American Chemical Society.

[18]  S. Saha,et al.  Effect of water on the molecular structure and arrangement of nitrile-functionalized ionic liquids. , 2006, The journal of physical chemistry. B.

[19]  T. Welton,et al.  Molecular states of water in room temperature ionic liquids , 2001 .

[20]  B. Han,et al.  Effect of water and organic solvents on the ionic dissociation of ionic liquids. , 2007, The journal of physical chemistry. B.

[21]  Robin D. Rogers,et al.  Ionic liquids : industrial applications for green chemistry , 2002 .

[22]  J. Prausnitz,et al.  Synthesis and Properties of Seven Ionic Liquids Containing 1-Methyl-3-octylimidazolium or 1-Butyl-4-methylpyridinium Cations , 2006 .

[23]  J. Wilkes.  Properties of ionic liquid solvents for catalysis , 2004 .

[24]  Á. Domínguez,et al.  Physical properties of pure 1 -ethyl -3 -methylimidazolium ethylsulfate and its binary mixtures with ethanol and water at several temperatures , 2006 .

[25]  C. Poole.  Chromatographic and spectroscopic methods for the determination of solvent properties of room temperature ionic liquids. , 2004, Journal of chromatography. A.

[26]  M. Watanabe,et al.  Physicochemical properties and structures of room temperature ionic liquids. 2. Variation of alkyl chain length in imidazolium cation. , 2005, The journal of physical chemistry. B.

[27]  C. Chiappe,et al.  Ionic liquids: solvent properties and organic reactivity , 2005 .

[28]  Kikuko Hayamizu,et al.  Physicochemical Properties and Structures of Room Temperature Ionic Liquids. 1. Variation of Anionic Species , 2004 .

[29]  Huizhi Chen,et al.  Densities and Viscosities of 1-Butyl-3-methylimidazolium Tetrafluoroborate + H2O Binary Mixtures from (303.15 to 353.15) K , 2006 .

[30]  C. Hardacre,et al.  Thermodynamics, structure, and dynamics in room temperature ionic liquids: the case of 1-butyl-3-methyl imidazolium hexafluorophosphate ([bmim][PF6]). , 2006, The journal of physical chemistry. B.