Structural Heterogeneities in Solutions of Triethylamine Nitrate Ionic Liquid: 1H NMR and LC Model Study

Abstract

In order to uncover the micro-structural heterogeneities in solutions of ammonium based ionic liquids, triethylamine nitrate (N 222 NO 3 ) has been synthesized using acid-base neutralization and the 1 H NMR spectra of two binary mixtures, namely N 222 NO 3 /dimethyl sulfoxide (DMSO) and N 222 NO 3 /acetone at different concentrations, have been measured at 298.15 K. The internal reference method was adopted to obtain the concentration-dependent chemical shifts of -CH 3 in N 222 NO 3 , which have been correlated using the 1 H NMR local composition (LC) model to obtain the local mole fractions. It has been revealed that within N 222 NO 3 rich region, self-association of the ionic liquid was predominant instead of N 222 NO 3 -solvent interactions. However, in the solvent rich region, N 222 NO 3 mainly interacts with solvent molecules, indicating that the self-association network of N 222 NO 3 has been greatly destroyed by solvents. In addition, the different influences of DMSO and acetone have been detected. DMSO molecules more effectively destroy the original network of the ionic liquid, due to its higher dielectric constant. Also, LC behavior in N 222 NO 3 /DMSO systems is more significant than in N 222 NO 3 /acetone, indicating that DMSO can induce more obvious heterogeneities in DMSO/N 222 NO 3 mixtures, which is consistent with physicochemical properties and cellulose solubility of solutions.

Transport Properties of the 1-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)amide–Trichloromethane Binary System: Indication of Trichloromethane Segregation

“…The presence of molecular solvent pools dispersed throughout the IL framework would allow for faster translational motion of the molecular solvent within these pools. This would explain the fast self-diffusion of CHCl 3 in the IL, faster than expected based on the bulk viscosity …”

“…This would explain the fast self-diffusion of CHCl 3 in the IL, faster than expected based on the bulk viscosity. 46 In summary, the main insights gained from the analysis of the self-diffusion and viscosity data according to eqs 3 and 4 are that (a) an adjustment of the viscosity dependence according to eq 3 can account for some of the deviations from Stokes− Einstein behavior, (b) CHCl 3 is to some extent present in segregated form, and (c) the length scales of the self-diffusing species appear to be constant for the range of 0.1 < x IL < 0.9, which means that changes in the average size of the present speciation or changes in the mass-transport mechanism are only indicated for 0 < x IL < 0.1 and 0.9 < x IL < 1.0. We note that the persistence of the principle IL structure upon the addition of a second component to x IL well below 0.5 has been suggested several times.…”

“…Several thermophysical and transport properties have been measured for a significant number of completely miscible binary IL–molecular solvent systems for the entire composition range, especially volumetric properties, viscosity, acoustic properties, and mixing enthalpies . It has been attempted to classify and correlate some of these properties to the structure of the ILs and molecular solvents. , While a fair number of conductivity studies over large composition ranges of IL–organic solvent exists, − in the case of self-diffusion measurements, such studies have mostly focused on IL–water binary systems, − and self-diffusion studies on IL–organic solvent binary systems that cover wide composition ranges are scarce. , …”

DBU-Based Protic Ionic Liquids for CO2 Capture

“…DBU, imidazole (Im), 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2-isopropylimidazole, 2-ethyl-4-methylimidazole, 2-nitroimidazole, 2-phenylimidazole, 4-methylimidazole, and 4-nitroimidazole were obtained in the highest purity grade possible, and were used as received unless otherwise stated. The ILs were synthesized via neutralization of an appropriate superbase DBU with different substituted imidazole, which has very weak acidity of N–H, that have been used to prepare other protic ILs in our previous work. − After synthetic reaction, all of the IL samples were dried at 60 °C for 24 h before use in the vacuum drying oven (DZF-6020, Shanghai Jing Hong Laboratory Instrument Co., Ltd.), in which the vacuum degree is lower than 133 Pa. The rotary vane vacuum pump (VOP-100, Shanghai Yiheng Instruments Co., Ltd.) is used to supply the limit pressure of 6.7 × 10 –2 Pa.…”

Micelle Formation in Aqueous Solutions of Room Temperature Ionic Liquids: A Molecular Dynamics Study

“…This is a key property to study the structure of liquid systems or any other systems of particles and its behavior could be different depending on the system. This work deals with systems composed by ionic liquids in water solutions, which are heterogeneous systems as it has been extensively reported in literature. − Due to the formation of local structures, as it is the case of micelles, the behavior of RDFs of homogeneous and heterogeneous systems differs. − Hence, RDFs in the present case do not reflect correlations between particles A and B as in a homogeneous system, but still provide valuable information to understand the size of the AB aggregates in a colloidal, nonhomogenous system.…”