Tetrahydrothiophene‐Based Ionic Liquids: Synthesis and Thermodynamic Characterizations

Abstract

S‐alkyltetrahydrothiophenium, [CnTHT]+ bis(trifluorosulfonyl)imide, [NTf2]− room temperature ionic liquids (ILs) and tetraphenylborate, [BPh4]− salts with alkyl chain lengths from C4 to C10 have been prepared. The ILs and salts were characterized and their purity verified by 1H‐ and 13C‐nuclear magnetic resonance, elemental analysis, ion chromatography, Karl‐Fischer titration, single crystal X‐ray diffraction as well as thermogravimetric analysis. The experimentally determined density and viscosity decrease with increasing temperature. The experimental solubility of the [CnTHT][NTf2]‐ILs in water (75 to 2.2 mg/L for C4 to C10) was modelled with very good agreement by Perturbed Chain Statistical Associating Fluid Theory (PC‐SAFT), based on the extremely low vapor pressures for the [CnTHT][NTf2]‐ILs measured in this work (4.15 to 0.037 ⋅ 10−7×psat for C4 to C10). PC‐SAFT is able to predict and correlate different thermodynamic properties by estimating the Helmholtz residual energy.

Thermal Decomposition, Low Temperature Phase Transitions and Vapor Pressure of Less Common Ionic Liquids Based on the Bis(trifuoromethanesulfonyl)imide Anion

“…For the presently investigated ionic liquids, it varies from 136 ± 18 kJ/mol for m-C 6 H 4 (CH 2 ImMe)][NTf 2 ] 2 to 147 ± 12 and 147 ± 13 kJ/mol for [DABCO10][NTf 2 ] and [p-C 6 H 4 (CH 2 ImBu)][NTf 2 ] 2 , respectively, and finally to 180 ± 17 kJ/mol for [C 6 Py][NTf 2 ]. These values are consistent with those previously reported for the other ionic liquids [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ].…”

“…These experiments extended the previous measurements to less exploited ions, such as tetraalkylphosphonium cations, which render ILs significantly more volatile than alkyl-imidazolium ILs with comparable chain length [ 16 ]. On the contrary, ILs with the NTf 2 anion and tetrahydrothiophene based cations were reported to have p v similar to the corresponding series with imidazolium cations [ 17 ]. The cations [Ph4P] and Cs decrease the vapor pressure with respect to the imidazolium equivalents [ 18 ].…”

Extremely Low Vapor‐Pressure Data as Access to PC‐SAFT Parameter Estimation for Ionic Liquids and Modeling of Precursor Solubility in Ionic Liquids

“…ILs have already been parametrized with ePC‐SAFT based on liquid density in previous publications [4,17,18] . Therefore, ion‐specific parameters have been regressed including an IL‐cation chain length dependency with a total 16 IL‐anions and 8 IL‐cation groups investigated.…”

“…ILs have already been parametrized with ePC-SAFT based on liquid density in previous publications. [4,17,18] Therefore, ionspecific parameters have been regressed including an IL-cation chain length dependency with a total 16 IL-anions and 8 ILcation groups investigated. Using these pure-component parameters, gas solubility [19] and liquid-liquid equilibria with water [5] and other solvents [5] have been modelled successfully.…”

Crystalline chalcogenidometalate-based compounds from uncommon reaction media

“…1, left) are used, 31–36 or low-melting, eutectic, mixtures. 37 Upon having been applied successfully to the synthesis of oxide materials 38 and metal nanoparticles, 39–42 they were also discovered as excellent reaction medium for the preparation of chalcogenides. 43–45…”