Reactive Oligomeric Protic Cationic Linear Ionic Liquids with Different Types of Nitrogen Centers

Reactive linear oligo(ethylene oxides) containing terminal secondary hydroxyl groups and secondary amino groups combined with nitrogen heterocyclic fragments are synthesized by the reaction of oligo(oxyethylene glycol) α,ω-diglycidyl ether (М = 1.0 × 10³) with 1-(3-aminopropyl)imidazole, 2-aminopyridine, or 2-amino-3-methylpyridine. Protonation of the synthesized compounds by ethanesulfonic acid and p-toluenesulfonic acid at their different ratios is studied. This process makes it possible to obtain oligomeric linear protic cationic ionic liquids capable of condensation. The proton conductivity of oligomeric ionic liquids is investigated under anhydrous conditions in the temperature range of 40–120°С. The highest conductivity (1.36 × 10^–3 S/cm) is attained in the case of methylpyridinium ethanesulfonate oligomeric ionic liquid at 120°С. These compounds are thermally stable to a temperature of 250–290°С. They show promise for the synthesis of polymeric analogs of block ionic liquids suitable in the production of electrochemical devices for various purposes.     

Effect of Hydroxyl Groups in a Cation Structure on the Properties of Ionic Liquids

Two series of imidazolium ionic liquids with the bis(trifluoromethylsulfonyl)imide anion were synthesized, which differ by the presence of a hydroxyl group at the ω-position of the alkyl substituent in the cation structure (n_C = 2–8). The properties of the liquids were studied by DSC, TGA, and IR and NMR spectroscopy. Their thermal stability was studied, and the melting points, viscosity, and volatility in vacuum were measured. The effect of OH groups in the structure of the ionic liquid on its properties was evaluated.     

Synthesis and physicochemical properties of <Emphasis Type="Italic">N</Emphasis>-decylpyridinium salts with inorganic anions

Ionic liquids with N-decylpyridinium cation and inorganic anions SO ₄ ^2– , NO ₃ ^– , SCN^–, NO ₂ ^– , BF ₄ ^– were synthesized. The structure and composition of the synthesized compounds was proved by elemental analysis and IR spectroscopy. Electroconductivity of aqueous solutions of new ionic liquids was studied, critical concentrations of micelle formation was determined, and thermal stability in air in the temperature range 25–500°С was investigated.     

Physicochemical properties of compounds of alkyl sulfates and cationic copper(II) complexes with some organic reagents

Compounds of alkyl sulfates and cationic copper(II) complexes with some organic reagents (pyridine, 1,10-phenanthroline, 2,2'-dipyridyl) were prepared, and their physicochemical characteristics (composition, thermal stability, solubility) were determined. The synthesized compounds are poorly soluble (solubility product K_S = n×10^–20–n×10^–22) and thermally stable (90–260°С). An effect of the hydrophobilicity of alkyl sulfates on the UV characteristics of the copper(II)–organic reagent systems and on the solubility of the studied compounds was evaluated.     

Alkylation of 4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-imidazole-2-thiol with iodomethylsilanes and -siloxanes

The alkylation of 4,5-dihydro-1H-imidazole-2-thiol with 1-iodomethyl(dimethyl)phenylsilane, 1-(iodomethyl)-1,1,3,3,3-pentamethyldisiloxane, and 1,3-bis(iodomethyl)-1,1,3,3-tetramethyldisiloxane involved iodine-catalyzed cleavage of the Si–C_sp ² and Si–O bonds with liberated (in situ) hydrogen iodide to afford 2-({[(4,5-dihydro-1H-imidazolium-2-ylsulfanyl)methyl]-1,1,3,3-tetramethyldisiloxanylmethyl}sulfanyl)-4,5-dihydro-1H-imidazolium di- and tetraiodides. Replacement of iodide ion in the products by triiodide gives new organosilicon ionic liquids with several charged fragments.     

Thermal stability and structure of a new co-crystal of theophylline formed with phthalic acid

A new co-crystal of theophylline and phthalic acid with 1:1 molar ratio has been prepared. It crystallises in the monoclinic crystal system, space group P2₁/c, a=11.5258(9), b=10.1405(6), c=13.9066(12) Å, β=106.827(4)°. The structure of the co-crystal has been revealed by single crystal X-ray diffraction. An infinite helical polymeric chain is formed by intermolecular hydrogen bonds of the two neutral constituents. The hydroxyl group and carbonyl oxygen atom in one of the carboxyl groups of phthalic acid form hydrogen bonds to O6 and to N(7)H atoms of theophylline, respectively, while the other carboxyl OH group of phthalic acid is in hydrogen bond to N9 atom of theophylline by very strong intermolecular interactions proven by 1883 cm^?1 centred peak in FTIR spectrum.Thermal degradation of this new supramolecular compound is a two-step process in air. At first phthalic acid (47.4%) released up to 230°C, meanwhile it loses water and transforms into phthalic anhydride. In EGA-MS spectra, the characteristic fragments of water (m/z=17, 18) appear from about 180°C, while absorption bands of phthalic anhydride are shown in EGA-FTIR spectrum at about 210°C. In the second step theophylline begins to sublime, melts at 276°C, and then evaporates up to 315°C with minute residues.     

Local structure of ionic liquid–monohydric alcohol solutions

The method of molecular dynamics is used to investigate the effect of monohydric alcohols on the formation of the local structure of ionic liquids based on the dimethylimidazolium cation at T = 400 K. The intermolecular interaction energies are analyzed to find that the increase in the length of the alkyl chain in the alcohol molecule reduces the influence of the solute molecule on the formation of the local structure of the dmim⁺/Cl^––solute molecule systems. An analysis of the radial distribution function shows that the change in the structure and physical characteristics of the solute molecule does not affect the interaction between the hydroxyl group proton of the alcohol molecule and the ionic liquid anions, whose interactions form the hydrogen bond H^alcohol…Cl^– with a length of 2.3 Å.     

Synthesis and physico-chemical properties of ionic liquids based on 1-butyl-3-alkylimidazolium with inorganic anions

Ionic liquids with 1-butyl-3-alkylimidazolium (alkyl = C₄H₉, C₈H₁₇, or C₁₀H₂₁) cation and Br^–, BF ₄ ^– , or PF ₆ ^– anions have been obtained. Composition and structure of the compounds have been confirmed by elemental analysis and IR spectroscopy data. Electrical conductivity of solutions of the synthesized compounds in acetonitrile has been studied, and association constant as well as equivalent electrical conductivity at infinite dilution have been calculated. Thermal stability of the prepared ionic liquids in air at 25–500°С has been studied.     

Endic acid diamides. Synthesis and reactivity

A number of symmetric and unsymmetric endo-cis-dicarboxamides of the norbornene series containing dimethyl- and diethylamine, morpholine, perhydroazepine, and p-bromoaniline fragments were synthesized starting from endic anhydride with the aid of N,N′-dicyclohexylcarbodiimide. Oxidation of these amides with organic peroxy acids according to Prilezhaev gave exo-2-hydroxy-5-oxo-4-oxatricyclo[4.2.1.0^3,7]-nonane-endo-9-carboxylic acid salts. The structure of the obtained products was confirmed by IR and ¹H NMR spectroscopy.     

Thermodynamics of the sorption of organic vapors in a carbosilane dendrimer and a hyperbranched polymer

Fluorinated derivatives of the carbosilane G6 dendrimer and the hyperbranched polymer of the same chemical structure are synthesized and characterized via the method of inverse gas chromatography. For various organic compounds (n-alkanes, aromatic hydrocarbons, partially fluorinated and perfluorinated organic compounds), the following thermodynamic parameters of their interaction with the above polymers are defined: solubility coefficient S, the sorption enthalpy, the partial molar enthalpy of mixing, the Flory-Huggins parameter, and the solubility parameter. The thermodynamic behavior of vapors in the dendrimer is similar to that in the hyperbranched polymer. For a dendrimer and a hyperbranched polymer, a linear correlation between the logarithm of S and T _cr ² is established, where T _cr is the critical temperature of a probe. For both polymers, the partial enthalpy of mixing of n-alkanes is shown to be independent of the dimensions of the probe molecules. This behavior is typical of the vapor sorption in linear polymers at temperatures above the glass transition temperature.     

Synthesis of Block Copolymers of Styrene with <Emphasis Type="Italic">D</Emphasis>,<Emphasis Type="Italic">L</Emphasis>-Lactide by the Sequential Controlled Cationic Polymerization and Ring-Opening Anionic Polymerization

The cationic polymerization of styrene initiated by the system 2-chloro-2-phenylpropane–TiCl₄–pyridine is studied in a mixture CH₂Cl₂–n-hexane at a temperature of –80°С. It is shown that under these conditions polymerization occurs via the living mechanism at [monomer]: [initiator] ≤ 100. The method of preparing polystyrenes with terminal primary hydroxyl groups (M_n = 4000–10000 g/mol) by the sequential controlled cationic polymerization of styrene and the in situ alkylation of 4-phenoxy-1-butanol by polystyrene macrocations is proposed. The resulting functionalized polystyrenes are used as macroinitiators of anionic-coordination ring-opening polymerization of D,L-lactide in the presence of tin bis(2-ethyl hexanoate) [Sn(Oct)₂] in toluene at 80°С. Copolymers polystyrene-block-poly(D,L-lactide) with the controlled length of the poly(D,L-lactide) block (M_n = 10000–17000 g/mol) and a relatively low molecular-weight distribution (M_w/M_n = 1.6–1.8) are synthesized. Formation of the block copolymers is confirmed by ¹Н NMR spectroscopy, gel-permeation chromatography, and atomic force microscopy.     

Protic cationic oligomeric ionic liquids of the urethane type

Protic oligomeric cationic ionic liquids of the oligo(ether urethane) type are synthesized via the reaction of an isocyanate prepolymer based on oligo(oxy ethylene)glycol with M = 1000 with hexamethylene-diisocyanate followed by blocking of the terminal isocyanate groups with the use of amine derivatives of imidazole, pyridine, and 3-methylpyridine and neutralization of heterocycles with ethanesulfonic acid and p-toluenesulfonic acid. The structures and properties of the synthesized oligomeric ionic liquids substantially depend on the structures of the ionic groups. They are amorphous at room temperature, but ethanesulfonate imidazolium and pyridinium oligomeric ionic liquids form a low melting crystalline phase. The proton conductivities of the oligomeric ionic liquids are determined by the type of cation in the temperature range 80–120°C under anhydrous conditions and vary within five orders of magnitude. The resulting compounds are thermally stable up to 200–270°C.     

Three-Component Reaction of 4-Methylpyridine with Alkyl Propiolates and Secondary Phosphine Chalcogenides

The reaction between 4-methylpyridine, alkyl propiolates, and secondary phosphine oxides proceeded as N-vinylation-C-phosphorylation with stereo- and regioselective formation of (E)-N-ethenyl-C²- phosphoryl-1,2-dihydropyridines [when using bis(2-phenylethyl)phosphine oxide] or (E)-N-ethenyl-C⁴- phosphoryl-1,4-dihydropyridines (when using diphenylphosphine oxide). The process occurred at 60–62°C within 3 h to give functional dihydropyridines in 40–82% yield. Under similar conditions, bis(2-phenylethyl) phosphine sulfide and selenide reacted with alkyl propiolates preferably by nucleophilic PH-monoaddition at the triple bond.     

Synthesis,characterization, DNA binding,antibacterial, and antioxidant activity of new bis-phthalimides

New bis-phthalimides were synthesized by 2: 1 condensation of phthalic anhydride and tetrachlorophthalic anhydride with 1,2,4-triazole-3,5-diamine, pyridine-2,6-diamine, and 4-hydroxypyrimidine- 2,6-diamine. The synthesized compounds were characterized by elemental analyses and IR, ¹H NMR, and mass spectra. Their interaction with calf thymus DNA (ct-DNA) was studied by UV-Vis spectrophotometry, cyclic voltammetry, and viscosity measurements, which revealed intercalative mode of binding to ct-DNA. Antibacterial activity of the synthesized compounds against Escherichia coli and Streptococcus mutans was assessed in vitro by the agar well diffusion method. The antioxidant activity of these compounds was estimated by DPPH assay.     

Potentiometric sensors based on new active components in the multisensor determination of homologues anionic surfactants

Potentiometric sensors are proposed on the basis of alkyl sulfates and cationic copper(II) complexes with organic reagents selective to anionic surfactants. Physical and chemical properties of the ionophores (composition, thermal stability, solubility) are determined in aqueous solutions and in the membrane phase. The studied compounds are poorly soluble (K _s = n × 10^–22–n × 10^–20) and thermally stable at 80?90°C. The main electroanalytical properties of sensors are estimated, i.e., analytical range in solutions of sodium alkyl sulfates 2 × 10^–7–1 × 10^–2 M; 46 <α < 66 mV/рc; LOD = 1 × 10^–7 M; response time 8–9 s in a solution of sodium dodecyl sulfate with the concentration not lower than 1 × 10^–4 M; potential drift 2–3 mV/day; and lifetime 12 months. The multisensor determination of homologues sodium alkyl sulfates in model mixtures and natural waters is performed using the proposed sensors.     

Tri-<Emphasis Type="Italic">n</Emphasis>-butyl phosphate–ionic liquid mixtures for Li<Superscript>+</Superscript> extraction from Mg<Superscript>2+</Superscript>-containing brines at 303–343 K

Extraction of Li⁺ ions from salt lake brine into an ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₂mim][NTf₂]) mixed with tri-n-butyl was investigated. The extraction mechanism was been studied using UV–Vis spectroscopy From the temperature dependence data, the thermodynamic functions values (ΔG°, ΔH°, and ΔS°) were calculated. Furthermore, stripping of metals from ionic liquid phase to an aqueous phase by hydrochloric acid was accomplished.     

Synthesis and structure of 1-(buta-1,3-dien-2-yl)pyrazoles and their behavior in Diels-Alder reactions

A convenient procedure has been developed for the synthesis of cis-and trans-isomeric 1-(buta-1,3-dien-1-yl)-1H-pyrazoles by reaction of the corresponding pyrazoles with β-methylacrolein diethyl acetal and subsequent 1,4-cleavage of the nucleophilic substitution products. The behavior of the title compounds in Diels-Alder reactions with maleic anhydride has been studied. According to the ¹H NMR data, 1-(buta-1,3-dien-1-yl)-1H-pyrazole is a mixture of cis and trans isomers. Butadienylpyrazoles having methyl groups in the pyrazole ring do not react with maleic anhydride.     

Synthesis of new alkoxysilyl-substituted carboranes

New 1,7-bis(trialkoxysilylpropyl)-m-carboranedicarboxamides were synthesized by the reaction of 3-aminopropyltrialkoxysilanes with either m-carboranedicarboxylic acid chloride in the presence of Et₃N or m-carboranedicarboxylic acid in the presence of N,N´-carbonyl-diimidazole. The synthesized compounds are colorless liquids soluble in benzene, toluene, tetrahydrofuran, diethyl ether, and chloroform and insoluble in water. Structures of the synthesized compounds were established by IR and NMR spectroscopy and confirmed by elemental analysis. The synthesized compounds are interesting starting materials for produc-tion of heat-resistant silicon carborane polymers and metal-carborane-silicon polymers.     

Dicationic polysiloxane ionic liquids

Dicationic ionic liquids with bis(trifluoromethylsulfonyl)imide anions and dimethylimidazolic moieties linked by the polymeric siloxane chain in the cation structure have been synthesized. Thermal stability of the compounds synthesised was studied by TGA; glass transition temperatures, viscosities and volatility in vacuo were measured. Applicability of these ionic liquids as heat carriers under high dynamic vacuum conditions is shown.     

Standard thermodynamic functions of complexation between copper(II) and glycine and L-histidine in aqueous solutions

The Cu²⁺–glycine–L-histidine system is studied calorimetrically at 298.15 K and an ionic strength of 0.2, 0.5, and 1.0 in aqueous solutions containing potassium nitrate. The standard thermodynamic parameters (Δ_rH°, Δ_rG°, Δ_rS°) of complexation processes are determined.