Reaction Of 1-methylimidazole Research Articles

The use of a microchannel reactor for optimizing the production of 1-alkyl-3-methylimidazolium chlorides

The possibility to use microchannel flow reactors for obtaining kinetic and technological parameters of the synthesis of 1-butyl-3-methylimidazolium chloride (BMIMCl) ionic liquid was demonstrated for the reaction of 1-methylimidazole (MIm) with 1-chlorobutane in the absence of solvents. BMIMCl was produced with high selectivity and specific output in a microchannel flow reactor at temperatures 120–180 °C and contact times 2-45 min at a pressure of 20 bar. The positive result is obtained due to the laminar profile of the flow and a uniform distribution of the reagents’ concentration over the microchannel cross-section. Investigation of the process kinetics in a microchannel flow reactor made it possible to reveal that the reaction moves to the diffusion resistance mode at a temperature above 150 °C. The kinetic data obtained for the BMIMCl synthesis were used to develop methods for the production of 1-ethyl-3-methylimidazolium and 1-hexyl-3-methylimidazolium chlorides (EMIMCl and HMIMCl, respectively) under the conditions of a microchannel flow reactor. The approach suggested in this paper is of interest for the development of flow and batch setups for a small-tonnage production of dialkylimidazolium, ammonium and pyridinium salts by quaternization of the corresponding alkyl chlorides and nitrogen-containing bases.

3,3′-(Dodecane-1,12-diyl)bis(1-methylimidazolium) 5,5′-azotetrazolate heptahydrate

The title compound, C20H36N4·C2N10·7H2O, was obtained by reaction of 1-methylimidazole with 1,12-dibromododecane, followed by repeated ion metathesis (bromide → sulfate → azotetrazolate). An intricate network of hydrogen bonds is formed between anions and water molecules, leading to a layered arrangement parallel to (101).

Six-coordinate nitrosyl complex of Co-meso-tetra-p-tolylporphyrin with a trans-1-methylimidazole ligand

Electron absorption and Fourier-transform IR spectroscopy was used to determine that the reaction of 1-methylimidazole (1-MeIm) with a nitrosyl complex of meso-tetra-p-tolylporphyrinate cobalt (Co(TTP)(NO)) at 210—240 K led to the formation of the six-coordinate complex (1-MeIm)Co(TTP)(NO), which was stable at low temperatures both in the solid state and in a solution of toluene. Based on the temperature dependence of the equilibrium constants, the thermodynamic parameters of complexation were calculated, which indicated a weak binding of the 1-methylimidazole ligand with the Co-porphyrin nitrosyl complex.

Proton transfer and hydrogen bonds in supramolecular, self-assembled structures of imidazolium silanethiolates. X-ray, spectroscopic and theoretical studies

The reaction of 1-methylimidazole, 2-ethyl-4-methylimidazole and 2-ethylimidazole with tris(2,6-diisopropylphenoxy)silanethiol (TDST) leads to the formation of three new salts, which have been characterized by elemental analyses, thermogravimetric analyses, FTIR spectroscopy, and their structures were determined by single-crystal X-ray diffraction. Structural analyses indicate that in all three compounds a proton transfer has occurred from the SH group of TDST onto the imidazole nitrogen atom, giving charge-assisted (+)N–H⋯S(−) hydrogen bonds. The crystallographic characterization of the compounds reveals structural diversity. Compound 1 exhibit zero-dimensional (0-D) hydrogen bonded entities, while compounds 2 and 3 form one-dimensional (1-D) supramolecular networks. The transfer of the proton was confirmed by FTIR spectroscopy in the solid state. Computational studies on the compounds were carried out with the use of the density functional theory (DFT) method with the B3LYP functional at the TZV level.

The synthesis of polysubstituted pyridines using nano Fe3O4 supported hydrogensulfate ionic liquid

Reaction of 1-methylimidazole with 3-(trimethoxysilyl)propyl chloride resulted in formation of 1-methyl-3-(trimethoxysilyl)propyl imidazolium chloride ([pmim]Cl). Anchoring of the ionic liquid on to silica-coated magnetic Fe3O4 particles afforded the corresponding supported ionic liquid MNP-[pmim]Cl. Exchanging the Cl− anion by treatment with H2SO4 gave the Bronsted ionic liquid MNP-[pmim]HSO4. FT-IR, XRD, SEM, TEM, TG/DTG, VSM, and CHN analysis were used to characterize the supported ionic liquid. The results indicated the catalyst was a nanostructure. The catalytic activity of the supported ionic liquid was examined in the synthesis of the polysubstituted pyridines by reaction of aromatic aldehydes, and acetophenones or indan-1-one with ammonium acetate under solvent-free conditions. The catalyst could be easily recovered, by applying an external magnetic field, and reused at least six runs without deterioration of its catalytic activity.

Ionic liquid immobilized on Fe3O4 nanoparticles: a magnetically recyclable heterogeneous catalyst for one-pot three-component synthesis of 1,8-dioxodecahydroacridines

A magnetically recoverable nanocatalyst based on 1-methylimidazolium hydrogen sulfate ionic liquid has been synthesized by reaction of 1-methylimidazole with 3-(trimethoxysilyl)propyl chloride group, leading to formation of 1-methyl-3-(triethoxysilyl)propyl imidazolium chloride ([pmim]Cl). The ionic liquid was anchored onto silica-coated magnetic Fe3O4 particles, and Cl− anion exchange by treatment with H2SO4 afforded the corresponding immobilized ionic liquid MNP-[pmim]HSO4. The synthesized catalyst was characterized by various techniques such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), (differential) thermogravimetry (TG/DTG), CHN analysis, and vibrating-sample magnetometry (VSM), revealing the superparamagnetic nature of the particles. From electron microscopy (SEM and TEM) studies it can be inferred that the particles were mostly spherical in shape with average size of 20 nm. The loading amount of ionic liquid supported on the magnetic particles was indicated to be 0.98 mmol/g by the results of elemental and thermogravimetric analyses (CHN and TG). The catalytic activity of the supported ionic liquid was examined in synthesis of 1,8-dioxodecahydroacridines by condensation reaction of cyclic diketones with aromatic aldehydes and ammonium acetate or primary amines under solvent-free conditions. The catalyst could be easily recovered by applying an external magnetic field and reused for at least nine runs without deterioration in catalytic activity.

Ionic liquid based Ru(II)–phosphinite compounds and their catalytic use in transfer hydrogenation: X-ray structure of an ionic compound 1-chloro-3-(3-methylimidazolidin-1-yl)propan-2-ol

The compound 1-chloro-3-(3-methylimidazolidin-1-yl)propan-2-ol chloride (1) was prepared from the reaction of 1-methylimidazole with epichlorohydrine. The corresponding phosphinite ligands were synthesized by the reaction 1-chloro-3-(3-methylimidazolidin-1-yl)propan-2-ol chloride, [C7H15N2OCl]Cl with one equivalent of chlorodiphenylphosphine or chlorodicyclohexylphosphine, in anhydrous CH2Cl2 and under an inert argon atmosphere. [Ru(η6-arene)(μ-Cl)Cl]2 dimers readily react with the phosphinite ligands [(Ph2PO)–C7H14N2Cl]Cl (2) or [(Cy2PO)–C7H14N2Cl]Cl (3) at room temperature to afford the cationic derivatives [Ru((Ph2PO)–C7H14N2Cl)(η6-arene)Cl2]Cl and [Ru((Cy2PO)–C7H14N2Cl)(η6-arene)Cl2]Cl {arene: benzene (4), (5); p-cymene (6), (7)}. The structures of these ligands and their corresponding complexes have been elucidated by a combination of multinuclear NMR and IR spectroscopy, TGA/DTA and elemental analysis. The molecular structure of the ionic compound 1 was also determined by an X-ray single crystal diffraction study. Furthermore, the catalytic activity of complexes 4–7 for the transfer hydrogenation of various ketones was investigated and these complexes were found to be efficient catalysts in the transfer hydrogenation of various ketones, with excellent conversions up to 99%. Specifically, [Ru((Cy2PO)–C7H14N2Cl)(η6-benzene)Cl2]Cl (5) and [Ru((Cy2PO)–C7H14N2Cl)(η6-p-cymene)Cl2]Cl (7) act as excellent catalysts, giving the corresponding alcohols in 98–99% conversions in 5min (TOF⩽1188h−1).

Novel benzyl-substituted N-heterocyclic carbene–silver acetate complexes: synthesis, cytotoxicity and antibacterial studies

From the reaction of 1-methylimidazole (1a), 4,5-dichloro-1H-imidazole (1b(I)) and 1-methylbenzimidazole (1c) with p-cyanobenzyl bromide (2a), non-symmetrically substituted N-heterocyclic carbene (NHC) [(3a-c)] precursors, 5,6-dimethyl-1H-benzimidazole (1d) and 4,5-diphenyl-1H-imidazole (1e) with p-cyanobenzyl bromide (2a) and benzyl bromide (2b), symmetrically substituted N-heterocyclic carbene (NHC) [(3d-f)] precursors were synthesised. These NHC-precursors were then reacted with silver(i) acetate to yield the NHC-silver complexes (1-methyl-3-(4-cyanobenzyl)imidazole-2-ylidene)silver(i)acetate (4a), (4,5-dichloro-1-(4-cyanobenzyl)-3-methyl)imidazole-2-ylidene)silver(i)acetate (4b), (1-methyl-3-(4-cyanobenzyl)benzimidazole-2-ylidene)silver(i)acetate (4c), (1,3-bis(4-cyanobenzyl)5,6-dimethylbenzimidazole-2-ylidene) silver(i) acetate (4d), (1,3-dibenzyl-5,6-dimethylbenzimidazole-2-ylidene) silver(i) acetate (4e) and (1,3-dibenzyl-4,5-diphenylimidazol-2-ylidene) silver(i) acetate (4f) respectively. Three NHC-precursors 3c-e and four NHC-silver complexes 4b and 4d-f were characterised by single crystal X-ray diffraction. Preliminary in vitro antibacterial activity of the NHC-precursors and NHC-silver complexes was investigated against Gram-positive bacteria Staphylococcus aureus, and Gram-negative bacteria Escherichia coli using the qualitative Kirby-Bauer disk-diffusion method. NHC-silver complexes have shown very high antibacterial activity compared to the NHC-precursors. All six NHC-silver complexes were tested for their cytotoxicity through MTT based in vitro tests on the human renal-cancer cell line Caki-1 in order to determine their IC₅₀ values. NHC-silver complexes 4a-f were found to have IC₅₀ values of 6.2 (±1.0), 7.7 (±1.6), 1.2 (±0.6), 10.8 (±1.9), 24.2 (±1.8) and 13.6 (±1.0) μM, respectively. These values represent improved cytotoxicity against Caki-1, most notably for 4c, which is a three times more cytotoxic than cisplatin (IC₅₀ value = 3.3 μM) itself.

Butyl-3-methylimidazolium Chloride Preparation in Supercritical Carbon Dioxide

A novel process for preparing an ambient-temperature ionic liquid precursor (1-butyl-3-methylimidazolium chloride) was developed. The reaction of 1-methyl imidazole with butyl chloride was conducted in supercritical carbon dioxide (scCO2) and followed by in situ scCO2 extraction for purifying the product, 1-butyl-3-methylimidazolium chloride. The yield of 1-butyl-3-methylimidazolium chloride could be >90%, according to the reaction in a scCO2 reaction environment. The residual reactants could be, in situ, removed completely using scCO2 extraction after the required reaction time. The conversion of the reaction is dependent positively and strongly on the pressure. The kinetics of the reaction in scCO2 could be described using the two-order irreversible reaction model. The reaction rate constant (k) is linearly dependent on the density of CO2 in the logarithmic coordinates. The 1H nuclear magnetic resonance (1H NMR) spectral data of the prepared 1-butyl-3-methylimidazolium chloride product was satisfactoril...

An imidazole-based P–N bridging ligand and its binuclear copper(I), silver(I) and palladium(I) complexes: synthesis, characterizations and X-ray structures

Reaction of 1-methylimidazole with n-BuLi in tetrahydrofuran at −78°C followed by addition of chlorodiphenylphosphine afforded a P–N bridging ligand, 2-(diphenylphosphino)-1-methylimidazole (dpim) in good yield. The structure of the ligand was determined by single crystal X-ray analysis. Reaction of a stoichiometric amount of the ligand with [Cu(MeCN) 4]ClO 4 in acetonitrile led to the binuclear complex [Cu 2(μ-dpim) 3(MeCN)](ClO 4) 2·2CH 3CN ( 1·2CH 3CN), whose structure was determined by single crystal X-ray analysis. The solid state structure shows that the two copper ions are held by three dpim ligands and the coordination geometry around each metal atom is different, one being three- and the other being four-coordinated. One of the copper ions forms a distorted tetrahedral array with two P and one N atoms from the dpim ligand and an additional N atom from an acetonitrile ligand, whereas the other copper ion is three coordinated with two N and one P atoms from the dpim ligand. The nitrate-bridged polymeric silver(I) complex, {[Ag 2(μ-dpim) 2(NO 3)](NO 3)} n ( 2) was prepared by the reaction of equimolar amounts of the ligand and silver nitrate in methanol and was characterized by IR, NMR and X-ray analysis. The dimeric unit, [Ag 2(μ-dpim) 2], possesses an eight-membered annular core structure with two ligands bridging the two metal ions in a head-to-tail configuration. Two types of nitrate ions are present in 2: one makes an infinite one-dimensional chain by joining the dimeric units through its two oxygen atoms in an anti– anti bridging mode whereas the other is disordered with a half occupancy and is located at the left and right sides of the chain. The dynamic behavior of 2 in acetone was also studied by variable temperature 31P NMR. The binuclear palladium(I) complex [Pd 2Cl 2(dpim) 2] ( 4) was prepared by a conproportionation reaction between complex [PdCl 2(dpim) 2] ( 3) and [Pd(dba) 2] (dba=dibenzylideneaceton). Only one geometric isomer, probably head-to-tail (HT), was formed in this reaction. Complex 3 was prepared by treating [PdCl 2(PhCN) 2] with two moles of ligand in dichloromethane solution. In this complex the ligand acts as a P-monodentate. In solution it exists as a mixture of cis and trans isomers.