| Imidazole | |
|---|---|
 |
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| IUPAC name | 1,3-diazole |
| Other names | Imidazole 1,3-diazacyclopenta-2,4-diene |
| SMILES | n1c[nH]cc1 |
| Identifiers | |
| CAS number | [288-32-4] |
| RTECS number | N13325 1985-86 |
| Properties | |
| Molecular formula | C3H4N2 |
| Molar mass | 68. IUPAC Nomenclature is a system of naming Chemical compounds and of describing the science of Chemistry in general CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to Registry of Toxic Effects of Chemical Substances ( RTECS) is a Database of Toxicity information compiled from the open scientific literature without reference A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Molar mass, symbol M, is the Mass of one mole of a substance ( Chemical element or Chemical compound) 08 g/mol |
| Appearance | white or pale yellow solid |
| Density | 1. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 23 g/cm3, solid |
| Melting point |
89-91 °C (362-364 K) |
| Boiling point |
256 °C (529 K) |
| Solubility in water | miscible |
| Acidity (pKa) | pKa=6. The melting point of a solid is the temperature range at which it changes state from solid to Liquid. The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. Water is a common Chemical substance that is essential for the survival of all known forms of Life. 993 |
| Structure | |
| Crystal structure | monoclinic |
| Coordination geometry |
planar 5-membered ring |
| Dipole moment | 12. In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. In Crystallography, the monoclinic Crystal system is one of the 7 lattice Point groups A crystal system is described by three vectors. The term coordination geometry is used in a number of related fields of chemistry and solid state chemistry/physics In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a 8 Cm*1030 |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | Corrosive |
| R-phrases | R20 R22 R34 R41 |
| S-phrases | S26 S36 S37 S39 S45 |
| Flash point | 146 °C |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Imidazole is a heterocyclic aromatic organic compound. A material safety data sheet ( MSDS) is a form containing data regarding the properties of a particular substance Occupational safety and health is a cross-disciplinary area concerned with protecting the Safety, Health and welfare of people engaged in R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous R-phrases (short for Risk Phrases) are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. The flash point of a flammable liquid is the lowest Temperature at which it can form an ignitable mixture in air In Chemistry, the standard state of a material is its state at 1 bar (100 Kilopascals exactly An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. It is further classified as an alkaloid. This article is about the chemical compounds alkaloids For the Pharmaceutical company in the Republic of Macedonia see Alkaloid (company. Imidazole refers to the parent compound C3H4N2, whereas imidazoles are a class of heterocycles with similar ring structure but varying substituents. This ring system is present in important biological building blocks such as histidine, and the related hormone histamine. Histidine (abbreviated as His or H) is one of the 20 standard Amino acids present in Proteins In the Nutritional sense in Histamine is a Biogenic amine involved in local immune responses as well as regulating physiological function in the gut and acting as a Neurotransmitter Imidazole can act as a base and as a weak acid. In Chemistry, a base is most commonly thought of as an aqueous substance that can accept Protons This refers to the Brønsted-Lowry theory of acids and In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are Imidazole exists in two tautomeric forms with the hydrogen atom moving between the two nitrogens. Tautomers are Organic compounds that are interconvertible by a Chemical reaction called tautomerization. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Many drugs contain an imidazole ring, such as antifungal drugs and nitroimidazole. An antifungal drug is Medication used to treat fungal Infections such as Athlete's foot, Ringworm, Candidiasis (thrush Nitroimidazoles are Imidazole Heterocycles with a Nitro group that have been used to combat anaerobic Bacterial and Parasitic [1][2][3][4][5]
Contents |
Discovery
Imidazole was first synthesized by Heinrich Debus in 1858, but various imidazole derivatives had been discovered as early as the 1840s. His synthesis, as shown below, used glyoxal and formaldehyde in ammonia to form imidazole. Glyoxal is an Organic compound with the formula OCHCHO This yellow-coloured liquid is the smallest Dialdehyde (two Aldehyde groups Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor [6] This synthesis, while producing relatively low yields, is still used for creating C-substituted imidazoles.
In one microwave modification the reactants are benzil, formaldehyde and ammonia in glacial acetic acid forming 2,4,5-triphenylimidazole (Lophine). Microwave chemistry is the science of applying Microwave irradiation to chemical reactions. Benzil is the Organic compound with the formula ( C 6 H 5C O)2 generally abbreviated ( PhCO 2 Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor Acetic acid, also known as ethanoic acid, is an organic chemical compound, giving Vinegar its sour taste [7]
Preparation
Imidazole can be synthesized by numerous methods besides the Debus method. Many of these syntheses can also be applied to different substituted imidazoles and imidazole derivatives simply by varying the functional groups on the reactants. In Organic chemistry, functional groups are specific groups of Atoms within Molecules that are responsible for the characteristic Chemical reactions In literature, these methods are commonly categorized by which and how many bonds form to make the imidazole rings. For example, the Debus method forms the (1,2), (3,4), and (1,5) bonds in imidazole, using each reactant as a fragment of the ring, and thus this method would be a three-bond-forming synthesis. A small sampling of these methods is presented below.
- Formation of One Bond
The (1,5) or (3,4) bond can be formed by the reaction of an immediate and an α-aminoaldehyde or α-aminoacetal, resulting in the cyclization of an amidine to imidazole. Amidines are a class of Oxoacid derivatives. The oxoacid from which an amidine is derived must be of the form R n E(=OOH where R is a The example below applies to imidazole when R=R1=Hydrogen.
- Formation of Two Bonds
The (1,2) and (2,3) bonds can be formed by treating a 1,2-diaminoalkane, at high temperatures, with an alcohol, aldehyde, or carboxylic acid. In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon An aldehyde is an organic compound containing a terminal Carbonyl group. Carboxylic acids are Organic acids characterized by the presence of a Carboxyl group, which has the formula -C(=OOH usually written -COOH or -CO2H A dehydrogenating agent, such as platinum with alumina, must be present in the reaction for the imidazole to form. Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 The example below applies to imidazole when R=Hydrogen.
The (1,2) and (3,4) bonds can also be formed from N-substituted α-aminoketones and formamide and heat. Formamide, also known as methanamide is an Amide derived from Formic acid. The product will be a 1,4-disubstituted imidazole, but here since R=R1=Hydrogen, imidazole itself is the product. The yield of this reaction is moderate, but it seems to be the most effective method of making the 1,4 substitution.
- Formation of Four Bonds
This is a general method which is able to give good yields for substituted imidazoles. The starting materials are substituted glyoxal, aldehyde, amine, and ammonia or an ammonium salt. [8]
- Formation from other Heterocycles
Imidazole can be synthesized by the photolysis of 1-vinyltetrazole. Photodissociation, photolysis, or photodecomposition is a Chemical reaction in which a Chemical compound is broken down by Photons Tetrazoles are a class of synthetic organic heterocyclic compound, consisting of a 5-member ring of four Nitrogen and one Carbon This reaction will only give substantial yields if the 1-vinyltetrazole is made efficiently from an organotin compound such as 2-tributylstannyltetrazole. Organotin compounds or stannanes are Chemical compounds based on Tin with Hydrocarbon substituents The reaction, shown below, produces imidazole when R=R1=R2=Hydrogen.
Imidazole can also be formed in a vapor phase reaction. The reaction occurs with formamide, ethylenediamine, and hydrogen over platinum on alumina, and it must take place between 340 and 480 °C. Formamide, also known as methanamide is an Amide derived from Formic acid. Ethylenediamine (abbreviated as en when a Ligand) is the Organic compound with the formula C2H4(NH22 This forms a very pure imidazole product.
Structure and properties
Imidazole is a 5-membered planar ring, which is soluble in water and polar solvents. "Polar molecule" and "Non-polar" redirect here The compound has an aromatic sextet, which consists of one π electron from the =N- atom and one from each carbon atom, and two from the NH nitrogen. History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Some resonance structures of imidazole are shown below. In Physics, resonance is the tendency of a system to Oscillate at maximum Amplitude at certain frequencies, known as the system's 
Imidazole is a base and an excellent nucleophile. In Chemistry, a nucleophile (literally nucleus lover as in nucleus and phile) is a Reagent that forms a Chemical bond to It reacts at the NH nitrogen, attacking alkylating and acylating compounds. It is not particularly susceptible to electrophilic attacks at the carbon atoms, and most of these reactions are substitutions that keep the aromaticity intact. In Chemistry, an electrophile (literally electron-lover) is a Reagent attracted to Electrons that participates in a chemical reaction by accepting One can see from the resonance structure that the carbon-2 is the carbon most likely to have a nucleophile attack it, but in general nucleophilic substitutions are difficult with imidazole.
Biological significance and applications
Imidazole is incorporated into many important biological molecules. The most obvious is the amino acid histidine, which has an imidazole side chain. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Histidine (abbreviated as His or H) is one of the 20 standard Amino acids present in Proteins In the Nutritional sense in A side chain in Organic chemistry and Biochemistry is a part of a Molecule that is attached to a core structure Histidine is present in many proteins and enzymes and plays a vital part in the structure and binding functions of hemoglobin. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Hemoglobin ( also spelled haemoglobin and abbreviated Hb or Hgb) is the Iron -containing Oxygen -transport Metalloprotein Histidine can be decarboxylated to histamine, which is also a common biological compound. Carboxyl group or CO2H is a Functional group present in Amino acids and Carboxylic acids Its structure is composed of one carbon atom attached Histamine is a Biogenic amine involved in local immune responses as well as regulating physiological function in the gut and acting as a Neurotransmitter It is a component of the toxin that causes urticaria, which is basically an allergic reaction. A toxin ( Greek:, toxikon, lit (poison for use on arrows is a Poisonous substance produced by living cells or organisms that is active at very low Allergy is a disorder of the Immune system often also referred to as Atopy. The structures of both histidine and histamine are: 
One of the applications of imidazole is in the purification of His-tagged proteins in immobilised metal affinity chromatography(IMAC). A polyhistidine-tag is an Amino acid motif in Proteins that consists of at least six Histidine ( His) residues often at the N- or C-terminus Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Chromatography (from Greek χρώμα chroma, color and γραφειν"graphein" to write is the collective term for a family of Laboratory Imidazole is used to elute tagged proteins bound to Ni ions attached to the surface of beads in the chromatography column. Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge An excess of imidazole is passed through the column, which displaces the His-tag from nickel co-ordination, freeing the His-tagged proteins.
Imidazole has become an important part of many pharmaceuticals. Synthetic imidazoles are present in many fungicides and antifungal, antiprotozoal, and antihypertensive medications. Fungicides are Chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores An antifungal drug is Medication used to treat fungal Infections such as Athlete's foot, Ringworm, Candidiasis (thrush Antiprotozoal agents ( ATC code ATC P01 is a class of Pharmaceuticals used in treatment of Protozoan infection. Antihypertensives are a class of drugs that are used in Medicine and Pharmacology to treat Hypertension (high blood pressure Imidazole is part of the theophylline molecule, found in tea leaves and coffee beans, which stimulates the central nervous system. Theophylline, also known as dimethylxanthine, is a Methylxanthine drug used in therapy for Respiratory diseases such as COPD or Asthma In Vertebrates the central nervous system ( CNS) is the part of the Nervous system which is enclosed in the Meninges. It is present in the anticancer medication mercaptopurine, which combats leukemia by interfering with DNA activities. Mercaptopurine (also called 6-Mercaptopurine 6-MP or its brand name Purinethol) is an Immunosuppressive drug used to treat Leukemia. Leukemia or leukaemia (Greek leukos λευκός, "white" aima αίμα, "blood" is a Cancer of the Blood Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known
Industrial applications
Imidazole has been used extensively as a corrosion inhibitor on certain transition metals, such as copper. Preventing copper corrosion is important, especially in aqueous systems, where the conductivity of the copper decreases due to corrosion.
Many compounds of industrial and technological importance contain imidazole. The thermostable polybenzimidazole PBI contains imidazole fused to a benzene ring and linked to a benzene, and acts as a fire retardant. Benzene, or benzol, is an organic Chemical compound and a known Carcinogen with the molecular formula C 6 H 6 Imidazole can also be found in various compounds which are used for photography and electronics.
Salts of imidazole
Salts of imidazole where the imidazole ring is in the cation are known as imidazolium salts (for example, imidazolium chloride). An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge These salts are formed from the protonation or substitution at nitrogen of imidazole. In chemistry protonation is the addition of a proton ( H[[Cation +]] to an Atom, Molecule, or Ion. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 These salts have been used as ionic liquids and precursors to stable carbenes. An ionic liquid is a liquid that contains essentially only ions Some ionic liquids such as Ethylammonium nitrate are in a dynamic equilibrium where at any time more A persistent carbene (also known as a stable carbene or an Arduengo carbene is a type of Carbene demonstrating particular stability despite also being a Reactive Salts where a deprotanated imidazole is an anion are also possible; these salts are known as imidazolide salts (for example, sodium imidazolide). An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge
Related heterocycles
- Benzimidazole, an analog with a fused benzene ring. Benzimidazole is a Heterocyclic Aromatic Organic compound. This bicyclic compound consists of the fusion of Benzene and Imidazole Benzene, or benzol, is an organic Chemical compound and a known Carcinogen with the molecular formula C 6 H 6
- Dihydroimidazole or benzimidazoline, an analog where 4,5-double bond is saturated. Imidazoline is a Nitrogen -containing heterocycle derived from Imidazole.
- Pyrrole, an analog with only one nitrogen atom in position 1. Pyrrole, or pyrrol, is a Heterocyclic Aromatic Organic compound, a five-membered ring with the formula C 4 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny
- Oxazole, an analog with the nitrogen atom in position 1 replaced by oxygen. Oxazole is the parent compound for a vast class of heterocyclic Aromatic Organic compounds Thse are Azoles with an oxygen and a nitrogen Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the
- Thiazole, an analog with the nitrogen atom in position 1 replaced by sulfur. Thiazole, or 13-thiazole, is a clear to pale yellow flammable liquid with a Pyridine -like odor and the molecular formula C3H3NS Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16
- Pyrazole, an analog with two adjacent nitrogen atoms. Pyrazole refers both to the class of Simple aromatic ring Organic compounds of the Heterocyclic series characterized by a 5-membered Ring structure Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14
References
- ^ Alan R. Katritzky; Rees. Alan R Katritzky ( August 13, 1928 &ndash) is a British-American chemist now working at the University of Florida. Comprehensive Heterocyclic Chemistry. Vol. 5, p. 469-498, (1984).
- ^ Grimmett, M. Ross. Imidazole and Benzimidazole Synthesis. Academic Press, (1997).
- ^ Brown, E. G. Ring Nitrogen and Key Biomolecules. Kluwer Academic Press, (1998).
- ^ Pozharskii, A. F, et. al. Heterocycles in Life and Society. John Wiley & Sons, (1997).
- ^ Heterocyclic Chemistry TL Gilchrist, The Bath press 1985 ISBN 0-582-01421-2
- ^ Heinrich Debus (1858). "Ueber die Einwirkung des Ammoniaks auf Glyoxal". Annalen der Chemie und Pharmacie 107 (2): 199 – 208. Official title Annalen der Chemie, 1832–1839 Annalen der Chemie und Pharmacie, 1840–1872 (ISSN 0075-4617 CODEN JLACBF doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Microwave-Mediated Synthesis of Lophine: Developing a Mechanism To Explain a Product Crouch, R. David; Howard, Jessica L. ; Zile, Jennifer L. ; Barker, Kathryn H. J. Chem. Educ. 2006 83 1658
- ^ US6,177,575 (2001-01-23) Anthony J. Arduengo, III Process for Manufacture of Imidazoles
Dictionary
imidazole
-noun
- (organic chemistry) A heterocyclic aromatic organic compound 1,3-diazole containing two nitrogen atoms in a five-membered ring; any of its derivatives
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