Limiting activity coefficients of 1-chlorobutane in water and in aqueous solutions of substances involved in synthesis of ionic liquids

Abstract

Abstract Limiting activity coefficients ( γ 1 ∞ ) were measured for 1-chlorobutane in water and in aqueous solutions of the additives 1-methylimidazole (MeIm), ionic liquid 1-butyl-3-methylimidazolium chloride (BMImCl), and sodium chloride (NaCl) at temperatures from 273.35 to 308.15 K and additive concentrations from 0 to 0.6 mol kg −1 employing the methods of inert gas stripping and exponential saturator. The data measured in this work enabled us to establish recommended temperature dependence for γ 1 ∞ of 1-chlorobutane in water. To this end, the present data were supplemented with (i) compiled and critically evaluated γ 1 ∞ data from the literature and (ii) an estimated value of infinite dilution partial molar heat capacity and subsequently fitted to a suitable model equation. The recommended values of γ 1 ∞ and from them inferred values of solubility, Henry’s law constant, and air–water partition coefficients are reported at several temperatures. The effect of the additives corresponds to either salting-in (MeIm, BMImCl) or salting-out (NaCl). The temperature and additive concentration dependence of γ 1 ∞ were fitted simultaneously using a five-parameter model equation. The enthalpy and entropy of the transfer of 1-chlorobutane from water to aqueous solutions of the additives were further derived, disclosing the thermodynamic origin of the observed salting-in/salting-out processes.