Thermal stability and decomposition mechanism of 1-ethyl-3-methylimidazolium halides

Ionic liquids (ILs) as new media for synthesis and as functional fluids in technical applications are still of high interest. Cooling a steel component from an annealing temperature of nearly 850 C down to room temperature in a liquid bath is a technically important process. The use of ionic liquids offers advantages avoiding film boiling of the quenching medium. However, such a high immersion temperature exceeds the thermal stability of the IL, for example such as [EMIm][NTf 2 ]. To obtain information about formation of potential toxic decomposition products, potential fragments at varied states of decomposition of [EMIm][NTf 2 ] were studied by various spectroscopic and gravimetric methods. For the first time it was possible to quantify fluorine-containing products via mass spectrometry coupled directly with thermogravimetric (TG) measurements. While chemical and spectroscopic analysis of thermally stressed ILs revealed no hints concerning changes of composition after quenching hot steel for several times, the mass-spectrometer (MS) coupled TG analysis gives information by comparing the decomposition behaviour of fresh and used ILs. A number of fragments were detected in low amounts confirming the proposed decomposition mechanism.Fig. 1 Chemical structure of [EMIm][NTf 2 ].

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“…8 major signals displayed in Fig. 28 They report, that the cation stays intact. For better understanding Fig.…”

Section: Resultsmentioning

confidence: 93%

Stability studies of ionic liquid [EMIm][NTf₂] under short-term thermal exposure

et al. 2016

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“…There are some theoretical and experimental studies of the thermal stability and decomposition mechanism of EMImBr. [15][16][17] In dynamic measurements EMImBr shows high stability up to temperatures 249• C. [15][16][17] Besides the possible use as the electrolytes in energy storage devices, the ionic liquids containing bromide anions have been reported as good corrosion inhibitors.18,19 For Au(hkl) electrodes in I − and Br − containing room temperature ionic liquids (RTIL) mixtures, the adsorption step charge transfer resistance was non-zero. 11,20,21 All mentioned properties established for EMImBr promise a good practical outcome for electrochemical devices.…”

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confidence: 99%

mentioning

confidence: 99%

“…• C. [15][16][17] Besides the possible use as the electrolytes in energy storage devices, the ionic liquids containing bromide anions have been reported as good corrosion inhibitors.…”

mentioning

confidence: 99%

“…• C. [15][16][17] Besides the possible use as the electrolytes in energy storage devices, the ionic liquids containing bromide anions have been reported as good corrosion inhibitors. 18,19 For Au(hkl) electrodes in I − and Br − containing room temperature ionic liquids (RTIL) mixtures, the adsorption step charge transfer resistance was non-zero.…”

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confidence: 99%

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Electrochemical Investigation of 1-Ethyl-3-methylimidazolium Bromide and Tetrafluoroborate Mixture at Bi(111) Electrode Interface

Siimenson

Lembinen

Oll

et al. 2016

J. Electrochem. Soc.

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Electrochemical characterization of the interface between Bi(111) surface and ionic liquid mixtures of 1-ethyl-3-methylimidazolium tetrafluoroborate with 1-ethyl-3-methylimidazolium bromide (EMImBF 4 + x% EMImBr) has been evaluated by using the electrochemical impedance spectroscopy, cyclic voltammetry methods and density functional theory calculations. Dependence of the experimental data on the bromide concentration and on the electrode potential has been analyzed. Comparison of adsorption data with Bi(111) | EMImBF 4 + x% EMImI interface shows that adsorption activity of halide ions from EMImBF 4 follows a similar trend as from the aqueous and organic electrolyte solutions. The adsorption activity of anions increases in order Cl − < Br − < I − , despite the fact that the solvation properties of relevant media are significantly different. We discuss this trend in the light of a possible application of the RTIL mixtures as an electrolyte for electrochemical energy storage devices like supercapacitors. The ionic liquids as electrolytes have been studied since the early 20 th century, but there is still much to be understood regarding some fundamental aspects. [1][2][3][4][5][6] Theoretical models that explain the dependence of the differential capacitance values on the electrode potentials have been worked out for the aqueous and non-aqueous electrolytes and molten salts. 7,8 However, in the case of the specific adsorption, there are no detailed models for the electrical double layer capacitance, that analyze the influence of the surface-active anion concentration and electrode potential on the specific interaction energy (including charge transfer) and on the distance of the closest approach of anions onto the metal electrode surface.5,9,10 Therefore, the detailed analysis and characterization of these complex electrode | ionic liquid interfaces (with the addition of ions that might have strong chemical interactions and high interaction energies with electrode surface layer atoms, demonstrating very negative Gibbs adsorption energy values, so-called strong specific adsorption properties) is considered our high priority. Bismuth, as an electrode material, has been studied widely and has shown good electrochemical stability and high reproducibility of the data. The properties are inevitable for detailed investigation of interfacial adsorption and faradaic charge transfer processes. The amount of previously measured adsorption data from different electrolytes (including electrochemical impedance spectroscopy and in situ STM methods) enables to develop more realistic, i.e. complex models for the electrical double layer capacitance, that analyze the influence of the surface-active anion addition on the inner layer structure, dielectric permittivity, effective dipoles moment for dipole created at metal|RTIL interface, etc. 7,[11][12][13][14] To continue with the systematic research of halide ions, 1-ethyl-3-methylimidazolium bromide (EMImBr) was selected for the source of bromide ions. There are some theoretical and e...

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Synthesis and Physical Properties of Tunable Aryl Alkyl Ionic Liquids (TAAILs)

Lerch

Straßner

2021

Chemistry A European J

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Tunable aryl alkyl ionic liquids (TAAILs) based on the imidazolium cation were first reported in 2009. Since then, a series of TAAILs with different properties due to the electron-donating or -withdrawing effect of the substituents at the aryl ring has been developed. Herein, a wide variety of those ionic liquids (ILs) is presented in terms of their cation structure. The authors synthesized ILs containing the bromide or bis(trifluoromethane)sulfonimide anion and 1-aryl-3-alkyl imidazolium cations with various substituents in the ortho and/ or para position of the phenyl ring and alkyl chains of different lengths varying from butyl to dodecyl. The differences of their physical properties (melting point, thermal decomposition, viscosity, electro-chemical window) of these ILs are reported according to their structure.

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Thermal stability and decomposition mechanism of 1-ethyl-3-methylimidazolium halides

Cited by 74 publications

References 22 publications

Stability studies of ionic liquid [EMIm][NTf₂] under short-term thermal exposure

Stability studies of ionic liquid [EMIm][NTf₂] under short-term thermal exposure

Electrochemical Investigation of 1-Ethyl-3-methylimidazolium Bromide and Tetrafluoroborate Mixture at Bi(111) Electrode Interface

Synthesis and Physical Properties of Tunable Aryl Alkyl Ionic Liquids (TAAILs)

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Thermal stability and decomposition mechanism of 1-ethyl-3-methylimidazolium halides

Cited by 74 publications

References 22 publications

Stability studies of ionic liquid [EMIm][NTf2] under short-term thermal exposure

Stability studies of ionic liquid [EMIm][NTf2] under short-term thermal exposure

Electrochemical Investigation of 1-Ethyl-3-methylimidazolium Bromide and Tetrafluoroborate Mixture at Bi(111) Electrode Interface

Synthesis and Physical Properties of Tunable Aryl Alkyl Ionic Liquids (TAAILs)

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Stability studies of ionic liquid [EMIm][NTf₂] under short-term thermal exposure

Stability studies of ionic liquid [EMIm][NTf₂] under short-term thermal exposure