Department of Chemistry, University of Kurdistan, Sanandaj, Iran.
J Phys Chem B. 2011 Nov 17;115(45):13227-40. doi: 10.1021/jp2055188. Epub 2011 Oct 19.
A systematic study of osmotic coefficient, conductivity, volumetric and acoustic properties of solutions of ionic liquid 1-hexyl-3-methylimidazolium chloride ([C(6)mim][Cl]) in various molecular solvents has been made at different temperatures in order to study of ionic association and solvation behavior of [C(6)mim][Cl] in different solutions. Precise measurements on electrical conductances of solutions of [C(6)mim][Cl] in water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and acetonitrile at 293.15, 298.15, and 303.15 K are reported and analyzed with Barthel's low-concentration chemical model (lcCM) to obtain the limiting molar conductivities and association constants of this ionic liquid in the investigated solvents. Strong ion pairing was found for the ionic liquid in 2-propanol, 1-butanol, and 1-propanol, whereas ion association in acetonitrile, methanol and ethanol is rather weak and in water the ionic liquid is fully dissociated. In the second part of this work, the apparent molar volumes and isentropic compressibilities of [C(6)mim][Cl] in water, methanol, ethanol, acetonitrile, 1-propanol, 2-propanol, and 1-butanol are obtained at the 288.15-313.15 K temperature range at 5 K intervals at atmospheric pressure from the precise measurements of density and sound velocity. The infinite dilution apparent molar volume and isentropic compressibility values of the free ions and ion pairs of [C(6)mim][Cl] in the investigated solvents as well as the excess molar volume of the investigated solutions are determined and their variations with temperature and type of solvents are also studied. Finally, the experimental measurements of osmotic coefficient at 318.15 K for binary solutions of [C(6)mim][Cl] in water, methanol, ethanol, 2-propanol, and acetonitrile are taken using the vapor pressure osmometry (VPO) method and from which the values of the solvent activity, vapor pressure, activity coefficients, and Gibbs free energies are calculated. The results are interpreted in terms of ion association, ion-dipole interactions, and structural factors of the ionic liquid and investigated organic solvents. The ionic liquid is solvated to a different extent by the molecular solvents, and ionic association is affected significantly by ionic solvation.
已针对离子液体 1-己基-3-甲基咪唑氯化物 ([C(6)mim][Cl]) 在不同温度下于各种分子溶剂中的渗透系数、电导率、体积和声学性质进行了系统研究，以便研究 [C(6)mim][Cl] 在不同溶液中的离子缔合和溶剂化行为。报告并分析了在 293.15、298.15 和 303.15 K 下，[C(6)mim][Cl] 在水中、甲醇、乙醇、1-丙醇、2-丙醇、1-丁醇和乙腈中的溶液电导率的精确测量值，采用 Barthel 的低浓度化学模型 (lcCM) 获得了该离子液体在研究溶剂中的极限摩尔电导率和缔合常数。发现该离子液体在 2-丙醇、1-丁醇和 1-丙醇中存在强离子对，而在乙腈、甲醇和乙醇中离子缔合较弱，在水中则完全离解。在这项工作的第二部分中，在大气压下，从精确测量的密度和声速中，在 288.15-313.15 K 的温度范围内，每隔 5 K 获得了 [C(6)mim][Cl] 在水中、甲醇、乙醇、乙腈、1-丙醇、2-丙醇和 1-丁醇中的表观摩尔体积和等熵压缩率。确定了在所研究溶剂中 [C(6)mim][Cl] 的自由离子和离子对的无限稀释表观摩尔体积和等熵压缩率值以及所研究溶液的过量摩尔体积，并研究了它们随温度和溶剂类型的变化。最后，使用蒸汽压渗透压法 (VPO) 在 318.15 K 下测量了 [C(6)mim][Cl] 在水、甲醇、乙醇、2-丙醇和乙腈中的二元溶液的渗透压系数，并由此计算了溶剂活度、蒸气压、活度系数和吉布斯自由能的值。结果根据离子缔合、离子-偶极相互作用和离子液体及所研究有机溶剂的结构因素进行了解释。离子液体在不同程度上被分子溶剂溶剂化，离子缔合受到离子溶剂化的显著影响。
