Synthesis, spectroscopic characterization and acoustic, volumetric, transport and thermal properties of hydroxyl ammonium based ionic liquids (original) (raw)
Related papers
Thermophysical and spectroscopic study of pure N-methylcyclohexylammonium based ionic liquids
In this work, four ammonium based ionic liquids were synthesized by neutralization process between N-methylcyclohexylamine (NMC) and acids such as pentanoic acid, hexanoic acid, heptanoic acid and octanoic acid. Synthesized ionic liquids were characterized by spectroscopic methods namely 1 H NMR, 13 C NMR and FT-IR. Further, thermophysical properties viz. density (q) and speed of sound (u) values have been measured at atmospheric pressure (0.1 MPa) as a function of temperature over the range from (293.15 to 343.15) K. Moreover, refractive index was measured at T = 303.15 K and in turn molar refraction (R m) and free volume (f V) were calculated using the Lorentz–Lorenz relation. The experimental density values fitted with linear equation and correlated with the expected density proposed by Gardas– Coutinho model. Knowledge of the experimental density and speed of sound are useful to calculate thermodynamic properties such as thermal expansion coefficient (a) isentropic compressibility (b S) and free length theory (L f). The strength of ionic interaction between the ions was estimated by calculating lattice potential energy (U POT) and standard entropy (S°) as proposed by Glasser. Thermal decomposition temperatures (T d) were investigated using TG analysis. Finally, thermo physical properties of pure ILs were analyzed in terms of chemical structure of IL and its anionic part.
Thermophysical properties of sulfonium- and ammonium-based ionic liquids
Fluid Phase Equilibria, 2014
Experimental data for the density, viscosity, refractive index, and surface tension of four sulfonium-and ammonium-based ionic liquids (ILs) with the common bis(trifluoromethylsulfonyl)imide anion were measured in the temperature range between 288.15 and 353.15 K and at atmospheric pressure. The ILs considered include butyltrimethylammonium bis imide, [N 4111 ][NTf 2 ], tributylmethylammonium bis(trifluoromethylsulfonyl)imide, [N 4441 ][NTf 2 ], diethylmethylsulfonium bis(trifluoromethylsulfonyl)imide, [S 221 ][NTf 2 ], and triethylsulfonium bis(trifluoromethylsulfonyl)imide, [S 222 ][NTf 2
The Journal of Chemical Thermodynamics, 2008
The thermophysical properties of 1-hexyl-3-methyl imidazolium based hydrophobic room temperature ionic liquids (RTILs); with tetrafluoroborate (BF 4), hexafluorophosphate (PF 6), and bis(trifluoromethylsulfonyl)imide (Tf 2 N) anions, namely density q (298.15 to 348.15) K, dynamic viscosity g (288.2 to 348.2) K, surface tension r (298.15 to 338) K, and refractive index n D (302.95 to 332.95) K have been measured. The coefficients of thermal expansion a p values were calculated from the experimental density data using an empirical correlation. The thermal stability of all ILs is also investigated at two different heating rates (10 and 20)°C Á min À1) using thermogravimetric analyzer (TGA). The experimental results presented in this study reveal that the choice of anion type shows the most significant effect on the properties of ILs. The chloride and water contents of ILs (as impurities) are also investigated and reported in the present work.
Thermophysical properties and thermodynamic phase behavior of ionic liquids
Thermochimica Acta, 2006
The thermal stability of many tested ionic liquids (ILs) was investigated by the TGA and DTA curves over the wide temperature range from 200 to 780 K. The TGA curves have mainly a sigmoid shape, which can be split into three segments. The thermal decomposition of the samples was higher than 500 K. For the ammonium salts, C 2 BF 4 , or C 2 PF 6 , or C 2 N(CN) 2 , or C 4 Br, the temperatures of the decompositions were 583.5, 556.1, 545.1 and 525.3 K, respectively. Generally, it was found that the temperature of decomposition of investigated ionic liquid is strongly depended on the type of cation and the anion. Phase equilibria and thermophysical constants were measured also for the dialkoxy-imidazolium ILs, [(C 4 H 9 OCH 2) 2 IM][BF 4 ], [(C 8 H 17 OCH 2) 2 IM][Tf 2 N], [(C 10 H 21 OCH 2) 2 IM][Tf 2 N] and for pyridinium IL, [Pyr][BF 4 ]. The characterization and purity of the compounds were obtained by the elemental analysis, water content (Fisher method) and differential scanning microcalorimetry (DSC) analysis. From (DSC) method, the melting points, the enthalpies of fusion, the temperatures and enthalpies of solid-solid phase transitions and the half C p temperatures of glass transition of all investigated ionic liquids were measured. The phase equilibria of these salts with common popular solvents: water, or alcohols or n-alkanes, or aromatic hydrocarbons have been measured by a dynamic method from 290 K to the melting point of IL, or to the boiling point of the solvent in the whole mole fraction range, x from 0 to 1. These salts mainly exhibit simple eutectic systems with immiscibility in the liquid phase with upper critical solution temperatures (UCST), not only with aromatic hydrocarbons, cycloalkanes and n-alkanes but also with longer chain alcohols. For example the C 2 BF 4 salt show simple eutectic system with water and simple eutectic systems with immiscibility in the liquid phase with upper critical solution temperature with alcohols. The solid-liquid phase equilibria, SLE curves were correlated by means of the different G Ex models utilizing parameters derived from the SLE. The root-mean-square deviations of the solubility temperatures for all calculated data depend on the particular system and the equation used.
Thermophysical properties of ammonium and hydroxylammonium protic ionic liquids
In this work, five protic ionic liquids having propylammonium, 3-hydroxy propylammonium as cations and formate, acetate, trifluoroacetate as anions have been synthesized. Thermophysical properties such as density (q), viscosity (g) and sound velocity (u) have been measured at various temperatures ranging from (293.15 to 343.15) K at atmospheric pressure. The experimental density and viscosity were fitted with second order polynomial and Vogel–Tamman–Fulcher (VTF) equations, respectively. Also experimental densities were correlated with the estimated density proposed by Gardas and Coutinho model. The coefficient of thermal expansion (a) and isentropic compressibility (bs) values have been calculated from the experimental density and sound velocity data using empirical correlations. Lattice potential energy (UPOT) has been calculated to understand the strength of ionic interaction between the ions. Thermal decomposition temperature (Td) and glass transition temperature (Tg) along with crystallization and melting point were investigated using TGA and DSC analysis, respectively. The effect of alkyl chain length and electronegative fluorine atoms on anionic fragment as well as hydroxyl substituent on cationic side chain in the protic ionic liquids has been discussed for studied properties. The effect of DpKa over the studied properties has also been analyzed.
Journal of Chemical & Engineering Data, 2011
Heat capacity, glass-transition, crystallization, and melting temperatures of 1-ethyl-3-methylimidazolium ethylsulfate ([Emim][EtSO 4 ]) and 1-butyl-3-methylimidazolium methylsulfate ([Bmim][MeSO 4 ]) ionic liquids (ILs) have been determined by differential scanning calorimetry (DSC). Their thermal stabilities have been analyzed by thermogravimetric analysis (TGA). Given the effect of the heating rate over the decomposition temperatures, isothermal TGA experiments are proposed as a more appropriate method to evaluate the thermal stability of the ILs. Inside the working range (-150°C to 30°C), [Emim][EtSO 4 ] and [Bmim][MeSO 4 ] present a glass-transition temperature of-78.4°C and-91.9°C, respectively. [Bmim][MeSO 4 ] has a melting temperature of-4.1°C. The C p was determined in a working range (10°C to 100°C) where its value increases lineally with temperature.
Journal of Chemical & Engineering Data
In this work, a series of imidazolium-based ionic liquids with varying functionalities from aliphatic to aromatic groups and a fixed anion, bis[(trifluoromethane)sulfonyl]amide, were investigated. The imidazolium cations included 1-heptyl-3-methylimidazolium, 1-(cyclohexylmethyl)-3-methylimidazolium, 1-benzyl-3-methylimidazolium, 1,3-dibenzylimidazolium, and 1-(2-naphthylmethyl)-3-methylimidazolium. Structureproperty relationships were investigated regarding the substituent effects on the imidazolium cation, including n-alkyl versus cycloalkyl and aromatic versus aliphatic, as well as the effects of cation symmetry and larger aromatic polycyclic functionalities. Thermophysical properties investigated include density, thermal transition temperatures, and decomposition temperatures. The densities of the ionic liquids are governed by the substituents on the cation: n-alkyl < cycloalkyl < aromatic. The group contribution method is applicable for the density estimation of ionic liq...
Fluid Phase Equilibria, 2015
In order to evaluate the impact of the alkyl side chain length and symmetry of the cation on the thermophysical properties of water-saturated ionic liquids (ILs), densities and viscosities as a function of temperature were measured at atmospheric pressure and in the (298.15 to 363.15) K temperature range, for systems containing two series of bis(trifluoromethylsulfonyl)imide-based compounds: the symmetric [C n C n im][NTf 2 ] (with n = 1-8 and 10) and asymmetric [C n C 1 im][NTf 2 ] (with n = 2-5, 7, 9 and 11) ILs. For water-saturated ILs, the density decreases with the increase of the alkyl side chain length while the viscosity increases with the size of the aliphatic tails. The saturation water solubility in each IL was further estimated with a reasonable agreement based on the densities of water-saturated ILs, further confirming that for the ILs investigated the volumetric mixing properties of ILs and water follow a near ideal behaviour.
Industrial & Engineering Chemistry Research, 2018
The isobaric and isochoric heat capacities of six disubstituted imidazolium-based ionic liquids with different anions and two trisubstituted imidazolium-based bis(trifluoromethylsulfonyl)imides were determined at atmospheric pressure in the temperature range from 293.15 K to 323.15 K. The isobaric heat capacities were determined using differential scanning calorimetry. The isochoric heat capacities were determined indirectly by means of the acoustic method from the speed of sound and density measurements. Also, other connected with the speed of sound quantities such as isentropic and isothermal compressibilities as well as internal pressures were determined. The highest compressibilities show both trisubstituted imidazolium-based bis(trifluoromethylsulfonyl) imides, whereas 1-ethyl-3-methylimidazolium thiocyanate shows the lowest compressibility. The critical comparison of the isobaric heat capacity data with the available literature data makes possibility recommendation of the most reliable heat capacity values. Analyzed predictive capability of two heat capacity models based on group contribution method is poor in the case of [C(CN) 3 ]¯ anion. Additionally, based on the speeds of sound the thermal conductivities were calculated using a modified Bridgman relation and compared with values estimated by a group contribution method. Here, the worst results is obtained in the case of [SCN]¯ anion.