- Thermal behaviour of mixtures of 1-alkylpyridinium halides with and without a common ion
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The thermal behaviour of mixtures of 1-alkylpyridinium halide salts, comprising either three or four different types of ions, was investigated in order to develop a better understanding of this class of multi-ion systems. A total of six systems was examined, derived from all possible binary combinations of the following four salts: 1-butylpyridinium bromide ([C4Py]Br), 1-butylpyridinium chloride ([C4Py]Cl), 1-ethylpyridinium bromide ([C2Py]Br), and 1-ethylpyridinium chloride ([C2Py]Cl). The systems constituted by two of these salts with a common anion and therefore differing only in the length of the alkyl substituent of the cation (namely [C2Py]Br + [C4Py]Br and [C2Py]Cl + [C4Py]Cl) displayed a eutectic behaviour, with the eutectic compositions qualifying as ionic liquids (melting temperature below 373 K). In contrast, the systems having in common the cation and differing in the halide anion (namely [C2Py]Br + [C2Py]Cl and [C4Py]Br + [C4Py]Cl) showed the formation of solid solutions. The two remaining combinations ([C2Py]Br + [C4Py]Cl and [C2Py]Cl + [C4Py]Br), involving four different types of ions, were also found to display a eutectic behaviour. The melting point depressions of the eutectic points with respect to the parent salts were of about 30–70 K. This was also the liquid range increase achieved with the eutectic compositions, since their thermal stability was nearly the same as the similar thermal stabilities of their parent salts. All six binary combinations of the four 1-alkylpyridinium halides were also interpreted as subsystems of the general 4-ion system [C2Py]x[C4Py]1-xClyBr1-y (where x is the cationic fraction of [C2Py]+ and y is the anionic fraction of Cl?), and an analysis of the melting temperature throughout the domain of this system was carried out.
- Stolarska, Olga,Soto, Ana,Rodríguez, Héctor,Smiglak, Marcin
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- Merging structural frameworks of imidazolium, pyridinium, and cholinium ionic liquids with cinnamic acid to tune solution state behavior and properties
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Solubility in water, interactions with the solvent medium and tuning of molecular conformation in the liquid phase are the key issues to discover new biologically active molecules and to understand the mechanisms of their action. In the present article, we report synthesis, structural and biological activity studies, and computational modeling of new ionic compounds. Structural frameworks of well-known imidazolium, pyridinium and cholinium ionic liquids (ILs) were combined with naturally occurring cinnamic acid (CA), which is known to possess a wide spectrum of biological activity. Different combinations of these two structural elements (IL and Cin (cinnamic moiety)) allowed modulating the solubility, physicochemical properties and biological activity of the resulting molecules. A significant increase in the biological activity was achieved for the three studied hybrid molecules - [C4mim-Cin][Cl], [C4py–Cin][Cl], and [C4mim-Cin][Cin]. Multiparameter cytotoxicity mapping was performed to visualize the biological activity of the 28 studied molecules. Detailed experimental investigation and molecular dynamics simulation were performed to gain insight into the structure–activity relationship. Of note, a folding conformational change in the structure of [Cnmim-Cin][Cl] hybrid molecules in solution resulted in a substantial change in chemical reactivity, with the activation energy of the hydrolysis reaction decreasing from 32.1 to 23.9 kcal/mol.
- Ananikov, Valentine P.,Egorova, Ksenia S.,Gordeev, Evgeniy G.,Posvyatenko, Alexandra V.,Seitkalieva, Marina M.,Strukova, Elena N.,Vavina, Anna V.
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- Does alkyl chain length really matter? Structure-property relationships in thermochemistry of ionic liquids
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DSC was used for determination of reaction enthalpies of synthesis of ionic liquids [Cnmim][Cl]. A combination of DSC with quantum chemical calculations presents an indirect way to study thermodynamics of ionic liquids. The indirect procedure for vaporization enthalpy was validated with the direct experimental measurements by using thermogravimetry. First-principles calculations of the enthalpy of formation in the gaseous phase have been performed for the ionic species using the CBS-QB3 and G3 (MP2) theory. Experimental DSC data for homologous series of alkyl substituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with anions [Cl] and [Br] were collected from the literature. We have shown that enthalpies of formation, enthalpies of vaporization, and lattice potential energies are linearly dependant on the alkyl chain length. The thermochemical properties of ILs generally obey the group additivity rules and the values of the additivity parameters for enthalpies of formation and vaporization seem to be very close to those for molecular compounds.
- Verevkin, Sergey P.,Zaitsau, Dzmitry H.,Emel'Yanenko, Vladimir N.,Ralys, Ricardas V.,Yermalayeu, Andrei V.,Schick, Christoph
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- Alkylation process
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This invention relates to a process for the alkylation of aromatics by reacting an aromatic hydrocarbon with an olefin in the presence of an ionic liquid comprising (a) a compound of the formula Rn MX3-n wherein R is a C1-C6 alkyl radical, M is aluminium or gallium, X is a halogen atom and n is 0, 1 or 2 and, (b) a hydrocarbyl substituted imidazolium halide or a hydrocarbyl substituted pyridinium halide wherein at least one of the said hydrocarbyl substituents in the imidazolium halide is an alkyl group having 1-18 carbon atoms. The process allows ready separation of reaction products from the ionic liquid and improves selectivity to alkylated products.
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- Method for the preparation of 1-alkyl pyridinium chlorides
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A method for preparing alkyl pyridinium chlorides by effecting a direct reaction between the corresponding alkyl chloride and pyridine.
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