Thermodynamic Properties of 1-Butyl-3-methylimidazolium Hexafluorophosphate in the Condensed State

Abstract

Thermodynamic functions for 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) are reported in a range of temperatures from (5 to 550) K, based on new measurements by calorimetry. Heat capacities of the crystal, glass, and liquid phases for [C4mim][PF6] were measured with a pair of calorimeters. A vacuum-jacketed adiabatic calorimeter was used at temperatures between (5 and 310) K, and a heat bridge-scanning calorimeter was used from (300 to 550) K. With the adiabatic calorimeter, the fusion T fus = 283.51 K, = 19.60 kJ·mol-1, and the glass transition T g = 190.6 K were observed. The [C4mim][PF6] test sample was determined to have a mole fraction purity of 0.9956 by a fractional melting analysis. Densities of the liquid were measured in a range of temperatures from (298 to 353) K with a pycnometer equipped with a capillary neck. An unexpected endothermal transition, with a very small enthalpy change of 0.25 J·g-1 (0.071 kJ·mol-1), was observed in a range of temperatures from (394 to 412) K. Heat capacity jumps were determined at the glass transition C s = 81.6 J·K-1·mol-1 and fusion C s = 44.8 J·K-1·mol-1, and the observed entropy change at fusion is S (283.51 K) = 69.23 J·K-1·mol-1.

Thermal Properties of Ionic Liquids and Ionanofluids

“…Figure 7 shows the variation of heat capacity with temperature together with the results obtained from various research groups (Holbrey et al, 2003;Kabo et al, 2004;Fredlake et Table 7. Coefficients of equation (7) Fig . -Rebelo et al, 2004;-Kim et al, 2004;-Fredlake et al, 2004;-Waliszewski et al, 2005;-Van Valkenburg et al, 2005;-Garcia-Miaja et al, 2008;-Garcia-Miaja et al, 2009) -Holbrey et al, 2003;-Kabo et al, 2004;-Fredlake et al, 2004;-Troncoso et al, 2006) 2004; Troncoso et al, 2006). With the exception of the data reported by Kabo and co-workers (Kabo et al, 2004) which were obtained using a heat bridge calorimeter, all the remaining data were obtained using DSC.…”

“…Coefficients of equation (7) Fig . -Rebelo et al, 2004;-Kim et al, 2004;-Fredlake et al, 2004;-Waliszewski et al, 2005;-Van Valkenburg et al, 2005;-Garcia-Miaja et al, 2008;-Garcia-Miaja et al, 2009) -Holbrey et al, 2003;-Kabo et al, 2004;-Fredlake et al, 2004;-Troncoso et al, 2006) 2004; Troncoso et al, 2006). With the exception of the data reported by Kabo and co-workers (Kabo et al, 2004) which were obtained using a heat bridge calorimeter, all the remaining data were obtained using DSC. Our data agrees with the data of (Troncoso et al, 2006) between 0.4 and 0.6% and with (Kabo et al, 2004) between 0.8% and 1.2%.…”

“…With the exception of the data reported by Kabo and co-workers (Kabo et al, 2004) which were obtained using a heat bridge calorimeter, all the remaining data were obtained using DSC. Our data agrees with the data of (Troncoso et al, 2006) between 0.4 and 0.6% and with (Kabo et al, 2004) between 0.8% and 1.2%. Results with deviations greater than ± 2% are not included.…”

Ionic liquids as a tool for lignocellulosic biomass fractionation

“…Ionic liquids (ILs) are recognised to facilitate more green applications in reactions and separations due to their unique beneficial properties, such as negligible vapour pressure [8,9] and high thermal stability [10]. Their very low vapour pressure reduces the risk of exposure that is a clear advantage over the use of the classical volatile solvents.…”

Glass Transition Behavior of the Quaternary Ammonium-Type Ionic Liquid: N,N-Diethyl-N-methyl-N-(2-methoxyethyl)ammonium Bromide-H2O Mixtures

“…Although thermodynamic properties including T g have been so far investigated mainly on the imidazolium-based series of pure RTILs [10][11][12], we point out that investigations of glass transition behavior of the RTILs-H 2 O mixtures are still scarce. In previous work, we reported the glass transition behavior of the quaternary ammoniumtype ionic liquid, N,N-diethyl-N-methyl-N- (2- …”