288-32-4 Usage
chemical properties
Imidazole is between the two nitrogen atoms of five membered heterocyclic compounds containing. The unshared electron pair of 1-bit nitrogen atom in imidazole ring participates in the cyclic conjugation, reduces the electron density of the nitrogen atom, and makes hydrogen of the nitrogen atom easily leave in the form of hydrogen. Therefore imidazole has weak acidity, and can form salt with strong base.
The unshared electron pair of 3-bit nitrogen atom in imidazole ring doesn’t participates in the cyclic conjugation, while it occupies the sp2 hybridized orbital, can accept protons, and form salt with strong acid. Alkaline of imidazole is slightly stronger than pyrazole and pyridine.
There is tautomerism in the imidazole ring. The hydrogen on the 1-bit nitrogen atom can be transferred to the 3-atom, therefore, imidazole derivatives with same substituent respectively on 4-bit and 5-bit are tautomers.
Imidazole is stable to acid, and has antioxidant activity. Imidazole derivatives are widely found in nature, such as histamine, histidine and benzimidazole, etc.
There are some interesting reagents in acyl imidazole compounds. For example, 1-acetyl imidazole is a stable acylating agent, after reaction with pyrrole, it becomes 1-acetyl pyrrole. Furthermore, in general, 1-acetyl imidazole can get ketones and aldehydes using Grignard reagent and reducing agent. Reaction of N, N-carbonyldimidazole and carboxyl will get useful reagent acyl imidazole. The relationship between imidazole and natural compounds is very close. For example, pyrimidine ring turns into purine derivatives after condensation. In addition to being like 6-amino purine and guanine the nucleic acid bases, it also exists in the organisms of uric acid, caffeine and theophylline. The catalytic action of imidazole, such as accelerated enzyme hydrolysis, still under study. As the cause of allergic skin, its toxicity is similar todiamine. Rat oral LD501880mg/kg.
imidazole structure
Physical characteristics
In nature, there are only imidazole derivatives and no free imidazole. The precipitation from benzene is a colorless crystalline prism, with scents of ammonia. Relative molecular mass 68.08. Relative density 1.0303(101/4℃) . Melting point 89～91℃，boiling point 257℃，165℃～168℃(2.67×103Pa) and 138.2℃(1.60×103Pa). Flash point 145℃. Refractive index 1.4801(101℃). Viscosity 2.696mPa·s(100℃). Slightly soluble in benzene, petroleum ether, soluble in ether, acetone, chloroform and pyridine, easily soluble in water (at normal temperature 70) and ethanol. It appears weak alkaline. As the-NH-bond on 1 bite and-N= bond on 3 bit forms hydrogen bond, the boiling point is quite high; when 1 bit hydrogen is substituted, hydrogen bond cannot be formed, hence the boiling point decreases. As to thermal stability, it rarely dissolves under 250℃ (decomposition temperature is 590℃). It is also very stable to reducing agent and oxidant, but can form stable salt with inorganic acid. Owning some certain aromatic properties, also could get halogenation, nitration, sulfonation and hydroxymethylation in the presence of catalyst. Can be coupled with the heavy nitrogen salt in 2 bit. In addition, due to the =NH (1 bit) connected to the two double bonds, with some of the "acid", it can be replaced by metal to get salt. In addition, 3 bit nitrogen ions have coordination effect on metal ions, which can form chelate compounds. Although it is difficult to restore, but can be combined with the proton to generate cation type with resonance structure, and get of a stable form. Tautomers of imidazole ring are very easy to change, so it is hard to tell isomers on 4 bit or 5 bit.
The above information is edited by the lookchem He Liao Pu.
Chemical Properties
Imidazole is a moderately strong base (pKb= 7.0), and a weak acid (pKa= 14.9). Imidazoles substituted with electron-withdrawing groups are stronger acids than imidazole itself; e.g., 4(5)-nitroimidazole has a pKa of 9.3. Imidazole is stable at 400°C, possesses considerable aromatic character, and undergoes the usual electrophilic aromatic substitution reactions. Nitration and sulfonation require, however, far more drastic conditions than the corresponding reactions with benzene. Other substitution reactions of imidazole include halogenation, hydroxymethylation, coupling with aromatic diazonium salts, and carboxylation.
History
Imidazole[288-32-4] was first synthesized in 1858 by Debus from ammonia and glyoxal; it was originally named glyoxalin. The name imidazole was introduced by Hantzsch. Industrial production of imidazole began in the 1950s; a wide range of derivatives is now available in industrial quantities.
Uses
Imidazole is used as a buffer in the range of pH 6.2-7.8. It is also an histamine antagonist. It acts as a chelator and forms complexes with various divalent cations. It is used as a corrosion inhibitor on certain transition metals such as copper. Its derivatives, like polybenzimidazole (PBI), act as fire retardants. It finds application in photography and electronics. Imidazole salts are used as ionic liquids and precursors to stable carbenes. Imidazole derivatives like ketoconazole, miconazole and clotrimazole are involved in the treatment of various systemic fungal infections. It is a part of the theophylline molecule, present in tea leaves and coffee beans, which stimulates the central nervous system.
Application
Imidazole is a versatile heterocycle used in the preparation of various biologically active compounds such as the amino acid histidine and is present in many antifungal medication. It is also used ext ensively as a corrosion inhibitor on transition metals such as copper.It is used in organic synthesis and as an antiirradiationagent. Imidazole has been used:in the lysis, wash and elution buffer for the purification of histidine tagged Sonic Hedgehog(shh-N) protein.in elution buffer in stepwise gradient for the purification of histidine tagged aldo keto reductases using nickel affinity chromatography.as a component of homogenization buffer for the purification of phagosomal compartments from dendritic cell.
Preparation
Imidazole is formed by reacting glyoxal with formaldehyde in the presence of ammonium acetate in acetic acid. The driving energy is microwave radiation. More generally, this reaction is used to produce substituted imidazoles.Although there had been discoveries of various derivatives of imidazole in 1840, it was first reported in 1858. The synthesis process of imidazole follows the reaction between formaldehyde in ammonia and glyoxal. This process gives low yield of imidazole but it is still used to form imidazole with C-substitution (Wolkenberg et al., 2004).
Definition
ChEBI: Imidazole is an imidazole tautomer which has the migrating hydrogen at position 1. It is a conjugate base of an imidazolium cation. It is a conjugate acid of an imidazolide. It is a tautomer of a 4H-imidazole.
General Description
Imidazole is a heterocyclic compound with a five-membered planar ring. It is amphoteric and highly polar. The pharmacophore of imidazole exists in bioactive compounds including amino acids, plant growth regulators and therapeutic agents.
Health Hazard
It is less toxic relative to pyrrole and otherfive-membered heterocyclic compounds ofnitrogen. Intraperitoneal administration ofimidazole caused somnolence, muscle contractions,and convulsions in mice. Theoral LD50 value in mice is in the range900 mg/kg.
Flammability and Explosibility
Nonflammable
Biochem/physiol Actions
Imidazole derivatives have antibacterial, antifungal and anticancer functionality. It interacts with DNA and also binds to protein and stops cell division. It also acts as a microtubule destabilizing agents and inhibits topoisomerase and Cytochrome P450 Family 26 Subfamily A Member 1 (CYP26A1) enzymes. Imidazole based anticancer drug find applications in cancer chemotherapy. It is used as buffer component for purification of the histidine tagged recombinant proteins in immobilized metal-affinity chromatography (IMAC).
Purification Methods
Crystallise imidazole from *benzene, CCl4, CH2Cl2, EtOH, pet ether, acetone/pet ether and distilled de-ionized water. Dry it at 40o under vacuum over P2O5. Distil it at low pressure. It is also purified by sublimation or by zone melting. [Snyder et al. Org Synth Coll Vol III 471 1955, Bredereck et al. Chem Ber 97 827 1964, Caswell & Spiro J Am Chem Soc 108 6470 1986.] 15N-imidazole crystallises from *benzene [Scholes et al. J Am Chem Soc 108 1660 1986]. [Beilstein 23 II 34, 23 III/IV 564, 23/4 V 191.]
Check Digit Verification of cas no
The CAS Registry Mumber 288-32-4 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 2,8 and 8 respectively; the second part has 2 digits, 3 and 2 respectively.
Calculate Digit Verification of CAS Registry Number 288-32:
(5*2)+(4*8)+(3*8)+(2*3)+(1*2)=74
74 % 10 = 4
So 288-32-4 is a valid CAS Registry Number.
InChI:InChI=1/C3H4N2/c1-2-5-3-4-1/h1-3H,(H,4,5)
288-32-4Relevant articles and documents
Relation of the Transition-State Structure for the Water-Catalyzed Hydrolysis of 1-Acetylimidazolium Ion to Solvent Hydrophobicity: Proton Inventories in Water-Acetonitrile Mixtures
Huskey, William P.,Hogg, John L.
, p. 53 - 59 (1981)
The transition-state structure for the water-catalyzed hydrolysis of 1-acetylimidazolium ion has been probed in solvent systems which may mimic the hydrophobic nature of an enzyme's active site.The kinetic solvent deuterium isotope effect kH2O/kD2O, are 2.58, 2.49, and 2.10 in water, in 0.5 vol fraction of acetonitrile in water, and in 0.9 vol fraction of acetonitrile in water, respectively.The proton inventory investigations suggest all three solvent system entertain a transition-state structure composed of a catalytic proton bridge between the reorganizing substrate and a water molecule acting as a general base-catalyst.A "compression" of the transition-state structure in the solvent system containing the largest amount of acetonitrile is suggested to be responsible for the diminished kinetic solvent deuterium isotope effect.The reaction has been shown to be second order with respect to water.
Catalysis of the methanolysis of acetylimidazole by lanthanum triflate
Neverov, Alexei A.,Brown
, p. 1247 - 1250 (2000)
Methanolysis of acetylimidazole (1) and N-acetylimidazolepentamine-Co(III) (2) was found to be markedly accelerated in the presence of La(OTf)3. Potentiometric titration of a solution of La3+(OTf-)3 gave a pKa for the metal bound CH3OH of 7.22. The kinetics of methanolysis of 1 and 2 were measured at 25°C at various pH under buffered conditions as a function of increasing La3+. Analysis of both the kinetic and potentiometric data indicates that the catalytically active species is a La3+-dimer, bridged by two methoxides, (CH3OH)nLa3+(CH3O-) 2La3+(CH3OH)n. The maximum second-order rate constants for attack of the dimer on 1 and 2 are 1.50 × 103 M-1 s-1 and 1.42 × 102 M-1 s-1 respectively and both processes adhere to titration of a La3+(CH3OH) to generate the active form. The results are explained in terms of a mechanism where the methoxy-bridged La3+ dimer transiently breaks a La3+-OCH3 bond to expose both a CH3O- nucleophile and a La3+ which can act as a Lewis acid. Unlike the situation in water, the methanol results indicate that the medium greatly stabilizes and solubilizes the active dimer without the necessity of creating specially designed ligands to stabilize the dinuclear core.
The stability of N, N -carbonyldiimidazole toward atmospheric moisture
Engstrom, Kenneth M.,Sheikh, Ahmad,Ho, Raimundo,Miller, Robert W.
, p. 488 - 494 (2014)
N,N-Carbonyldiimidazole (CDI) is known to be sensitive to degradation by atmospheric moisture. This work details some mechanistic aspects of CDI degradation by atmospheric moisture along with the major contributing factors to degradation rate. Also, several analytical techniques for the measurement of CDI purity that are less cumbersome than the traditional gas-capture assay are described.
Development of a method for the quantification of clotrimazole and itraconazole and study of their stability in a new microemulsion for the treatment of sporotrichosis
Ferreira, Patricia Garcia,de Souza Lima, Carolina Guimar?es,Noronha, Letícia Lorena,de Moraes, Marcela Cristina,de Carvalho da Silva, Fernando,Vi?osa, Alessandra Lifsitch,Futuro, Débora Omena,Ferreira, Vitor Francisco
, (2019)
Sporotrichosis occurs worldwide and is caused by the fungus Sporothrix brasiliensis. This agent has a high zoonotic potential and is transmitted mainly by bites and scratches from infected felines. A new association between the drugs clotrimazole and itraconazole is shown to be effective against S. brasiliensis yeasts. This association was formulated as a microemulsion containing benzyl alcohol as oil, Tween 60 and propylene glycol as surfactant and cosurfactant, respectively, and water. Initially, the compatibility between clotrimazole and itraconazole was studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (PXRD). Additionally, a simple and efficient analytical HPLC method was developed to simultaneously determine the concentration of clotrimazole and itraconazole in the novel microemulsion. The developed method proved to be efficient, robust, and reproducible for both components of the microemulsion. We also performed an accelerated stability study of this formulation, and the developed analytical method was applied to monitor the content of active ingredients. Interestingly, these investigations led to the detection of a known clotrimazole degradation product whose structure was confirmed using NMR and HRMS, as well as a possible interaction between itraconazole and benzyl alcohol.
EFFECT OF THE SURFACE AREA OF PLATINUM ON THE ACTIVITY OF A BIFUNCTIONAL ALUMINOPLATINUM CATALYST IN THE SYNTHESIS OF ALKYLIMIDAZOLES FROM DIAMINES AND CARBONYL ACIDS
Gitis, K. M.,Raevskaya, N. I.,Zaitsev, A. V.,Borovkov, V. Yu.,Kozan, S. B.,Isagulyants, G. V.
, p. 1547 - 1550 (1992)
An investigation has been conducted into the effect of the acid and dehydrogenating functions of an aluminoplatinum catalyst on the synthesis of 2-methylimidazole from ethylenediamine and acetic acid.It has been established that formation of the intermediate 2-methylimidazoline involves the acid Al2O3 centers and its rate of formation is greater than the rate of its subsequent dehydrogenation to 2-methylimidazole on the Pt centers.The symbatic nature of the variations in the 2-methylimidazole yield and the surface area of the platinum in the aluminoplatinum catalyst has been demonstrated.Keywords: C-alkylimidazoles, 2-methylimidazole, aluminoplatinum catalyst.
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Shulman,Simmonds
, p. 1040 (1968)
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Method for protecting sulfonyl of deamination amine
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Paragraph 0048-0050, (2021/11/03)
The invention discloses a method for removing sulfenyl protection of amine. The method comprises the following steps: dissolving N - sulfonyl-protected amine and a base in a reaction solvent, then adding diphenylphosphine to uniformly mix and maintain 90 °C. When TCL detection reaction is complete, a recrystallization method or an extraction separation method is adopted to obtain the target product. The method disclosed by the invention adopts diphenylphosphine as an extraction reagent, is good in reaction activity, high in selectivity and wide in application range, and can replace the use of a hazardous reagent under the basic heating condition. Prodrug research and development and industrial production are of great significance.
Indirect reduction of CO2and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
Liu, Xin,Werner, Thomas
, p. 10590 - 10597 (2021/08/20)
The reduction of polar bonds, in particular carbonyl groups, is of fundamental importance in organic chemistry and biology. Herein, we report a manganese pincer complex as a versatile catalyst for the transfer hydrogenation of amides, carbamates, urea derivatives, and even polyurethanes leading to the corresponding alcohols, amines, and methanol as products. Since these compound classes can be prepared using CO2as a C1 building block the reported reaction represents an approach to the indirect reduction of CO2. Notably, these are the first examples on the reduction of carbamates and urea derivatives as well as on the C-N bond cleavage in amides by transfer hydrogenation. The general applicability of this methodology is highlighted by the successful reduction of 12 urea derivatives, 26 carbamates and 11 amides. The corresponding amines, alcohols and methanol were obtained in good to excellent yields up to 97%. Furthermore, polyurethanes were successfully converted which represents a viable strategy towards a circular economy. Based on control experiments and the observed intermediates a feasible mechanism is proposed.
