Indole
General
Systematic name	Indole
Other names	2,3-Benzopyrrole, ketole, 1-benzazole
Molecular formula	C8H7N
SMILES	C1(NC=C2)=C2C=CC=C1
Molar mass	117.15 g/mol
Appearance	White solid
CAS number	120-72-9
Properties
Density and phase	1.22 g/cm3, solid
Solubility in water	0.19 g/100 ml (20 °C) Soluble in hot water
In ethanol, ether In benzene	Highly soluble Soluble
Melting point	52 - 54°C (326 K)
Boiling point	253 - 254°C (526 K)
Acidity (pKa)	16.2 (21.0 in DMSO)
Basicity (pKb)	17.6
Structure
Molecular shape	Planar
Crystal structure	?
Dipole moment	2.11 D in benzene
Hazards
MSDS	External MSDS
Main hazards	?
NFPA 704	0 1 0
Flash point	121°C
R/S statement	R: 21/22-37/38-41-50/53 S: 26-36/37/39-60-61
RTECS number	NL2450000
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related aromatic compounds	benzene, benzofuran, carbazole, carboline, indene, indoline, isatin, methylindole, oxindole, pyrrole, skatole
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references

Indole is an aromatic heterocyclic organic compound. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. The participation of the nitrogen lone electron pair in the aromatic ring means that indole is not a base, and it does not behave like a simple amine. Image File history File links Indole_chemical_structure. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... This article or section does not cite any references or sources. ... The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... It has been suggested that this article or section be merged with Solution. ... This article describes water from a scientific and technical perspective. ... Grain alcohol redirects here. ... This article is about the chemical compound. ... Benzene, also known as benzol, is an organic chemical compound with the formula C6H6. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... The acid dissociation constant (Ka), also known as the acidity constant or the acid-ionization constant, is a specific equilibrium constant for the reaction of an acid with its conjugate base in aqueous solution [1]. // When an acid dissolves in water, it partly dissociates forming hydronium ions and its conjugate... Dimethyl sulfoxide (DMSO) is the chemical compound (CH3)2SO. This colorless liquid is an important dipolar aprotic solvent. ... The acid dissociation constant (Ka), also known as the acidity constant or the acid-ionization constant, is a specific equilibrium constant for the reaction of an acid with its conjugate base in aqueous solution [1]. // When an acid dissolves in water, it partly dissociates forming hydronium ions and its conjugate... four sp³ orbitals three sp² orbitals In chemistry, hybridisation or hybridization (see also spelling differences) is the concept of mixing atomic orbitals to form new hybrid orbitals suitable for the qualitative description of atomic bonding properties. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... The Earths magnetic field, which is approximately a dipole. ... The debye (symbol: D) is a non-SI and non-CGS unit of electrical dipole moment. ... Benzene, also known as benzol, is an organic chemical compound with the formula C6H6. ... An example MSDS in a US format provides guidance for handling a hazardous substance and information on its composition and properties. ... The examples and perspective in this article or section may not represent a worldwide view. ... NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ... Image File history File links NFPA_704. ... The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture with air. ... Risk and Safety Statements, also known as R/S statements, R/S numbers, R/S phrases, and R/S sentences, is a system of hazard codes and phrases for labeling dangerous chemicals and compounds. ... RTECS, also known as Registry of Toxic Effects of Chemical Substances, is a database of toxicity information compiled from the open scientific literature that is available for charge. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... Infrared spectroscopy (IR Spectroscopy) is the subset of spectroscopy that deals with the IR region of the EM spectrum. ... It has been suggested that NMR Data Processing be merged into this article or section. ... Mass spectrometry (also known as mass spectroscopy (deprecated)[1] or informally, mass-spec and MS) is an analytical technique used to measure the mass-to-charge ratio of ions. ... The term aromatic compound may also refer to: any organic compound possessing a strong olfactory aroma aromatic hydrocarbons (originally named as a subset of the above; however, aromatic hydrocarbons do not necessarily possess any smell whatsoever) ... Benzene, also known as benzol, is an organic chemical compound with the formula C6H6. ... Benzofuran, also known as Cumaron, Coumarone, or benzo[b]furan, is a heterocyclic aromatic organic compound. ... Chemical structure of carbazole Carbazole is an aromatic heterocyclic organic compound. ... β-Carboline (9H-pyrid-[3,4-b]-indole) is an organic amine that is the prototype of a class of compounds known as β-carbolines. ... Indene is a flammable polycyclic hydrocarbon with chemical formula C9H8 and CAS number 95-13-6. ... Indoline is an aromatic heterocyclic organic compound. ... Isatin or 1H-indole-2,3-dione is a indole derivative. ... A variety of isomers of methyl indole derivatives are known: 1-methylindole 2-methylindole skatole (3-methylindole) 4-methylindole 5-methylindole 6-methylindole 7-methylindole This is a disambiguation page, a list of pages that otherwise might share the same title. ... Chemical structure of oxindole Oxindole is an aromatic heterocyclic organic compound. ... Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H5N. Pyrroles are components of larger aromatic rings, including the porphyrins of heme, the chlorins and bacteriochlorins of chlorophyll, and the corrin ring of vitamin B12. ... Skatole or 3-methylindole is a mildly toxic white crystalline organic compound with chemical formula C9H9N and CAS number 83-34-1. ... In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... Pyridine a simple heterocyclic compound Heterocyclic compounds are organic compounds which contain a ring structure containing atoms in addition to carbon, such as sulfur, oxygen or nitrogen, as part of the ring. ... Benzene is the simplest of the arenes, a family of organic compounds An organic compound is any member of a large class of chemical compounds whose molecules contain carbon and hydrogen; therefore, carbides, carbonates, carbon oxides and elementary carbon are not organic (see below for more on the definition controversy... Benzene, also known as benzol, is an organic chemical compound with the formula C6H6. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H5N. Pyrroles are components of larger aromatic rings, including the porphyrins of heme, the chlorins and bacteriochlorins of chlorophyll, and the corrin ring of vitamin B12. ... A lone pair is an electron pair without bonding or sharing with other atoms. ... Acids and bases: Acid-base reaction pH Self-ionization of water Buffer solutions Systematic naming Acid-base extraction Acidity function Proton affinity Acids: Strong acids Weak acids Superacids Lewis acids Mineral acids Organic acids Bases: Strong bases Weak bases Superbases Lewis bases Organic bases edit In chemistry, a base is... The general structure of an amine Amines are organic compounds and a type of functional group that contain nitrogen as the key atom. ...

Indole is solid at room temperature. It occurs naturally in human feces and has an intense fecal odor. At very low concentrations, however, it has a flowery smell, and is a constituent of many flower scents (such as orange blossoms) and perfumes. It also occurs in coal tar. For other uses, see Solid (disambiguation). ... Feces, faeces, or fæces (see spelling differences) In humans, defecation may occur (depending on the individual and the circumstances) from once every two or three days to several times a day. ... Odor receptors on the antennae of a Luna moth An odor or odour (see spelling differences) is a chemical dissolved in air, generally at a very low concentration, which we perceive by the sense of olfaction. ... Olfaction, the sense of smell, is the detection of chemicals dissolved in air (or, by animals that breathe water, in water). ... For the book Perfume by Patrick Süskind, see Perfume (book). ... Coal tar is the liquid by-product of the distillation of coal to make coke. ...

The indole structure can be found in many organic compounds like the amino acid tryptophan and in tryptophan-containing protein, in alkaloids, and in pigments. Phenylalanine is one of the standard amino acids. ... Tryptophan is an amino acid and essential in human nutrition. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Chemical structure of ephedrine, a phenethylamine alkaloid An alkaloid is, strictly speaking, a naturally occurring amine produced by a plant,[1] but amines produced by animals and fungi are also called alkaloids. ... Natural Ultramarine pigment in powdered form. ...

Indole undergoes electrophilic substitution, mainly at position 3. Substituted indoles are structural elements of (and for some compounds the synthetic precursors for) the tryptophan-derived tryptamine alkaloids like the neurotransmitter serotonin, melatonin, the hallucinogens psilocybin, DMT, 5-MeO-DMT, or the ergolines like LSD. Other indolic compounds include the plant hormone Auxin (indolyl-3-acetic acid, IAA), the anti-inflammatory drug indomethacin, and the betablocker pindolol. Electrophilic substitution reactions are chemical reactions in which an electrophile displaces another group, typically but not always hydrogen. ... Tryptamine (3-(2-aminoethyl)indole) is a monoamine compound that is widespread in nature. ... Chemical structure of D-aspartic acid, a common amino acid neurotransmitter. ... Serotonin (5-hydroxytryptamine, or 5-HT) is a monoamine neurotransmitter synthesized in serotonergic neurons in the central nervous system (CNS) and enterochromaffin cells in the gastrointestinal tract of animals including humans. ... Melatonin, 5-methoxy-N-acetyltryptamine, is a hormone found in all living creatures from algae[1] to humans, at levels that vary in a diurnal cycle. ... The general group of pharmacological agents commonly known as hallucinogens can be divided into three broad categories: psychedelics, dissociatives, and deliriants. ... Psilocybin (also known as psilocybine) is a psychedelic alkaloid of the tryptamine family, found in psilocybin mushrooms. ... Dimethyltryptamine (DMT), also known as N,N-dimethyltryptamine, is a psychedelic tryptamine. ... 5-MeO-DMT is a very powerful psychedelic tryptamine. ... Chemical structure of ergoline Ergoline is a chemical compound whose structure serves as the skeleton for a diverse range of alkaloids and synthetic drugs. ... Lysergic acid diethylamide, commonly called LSD, LSD-25, or acid. ... IAA appears to be the most active Auxin in plant growth. ... Indole-3-acetic acid, also known as IAA, is a member of the group of phytohormones called auxins. ... Indomethacin (USAN) or indometacin (INN) is a non-steroidal anti-inflammatory drug commonly used to reduce fever, pain, stiffness, and swelling. ... Beta blockers or beta-adrenergic blocking agents are a class of drugs used to treat a variety of cardiovascular conditions and some other diseases. ... Pindolol is a beta blocker drug. ...

The name indole is portmanteau of the words indigo and oleum, since indole was first isolated by treatment of the indigo dye with oleum. A portmanteau (IPA pronunciation: ) is a word or morpheme which fuses two or more words or parts of words to give a combined or loaded meaning. ... Indigo dye indigo molecule Indigo dye is an important dyestuff with a distinctive blue color (see indigo). ... Oleum refers to a solution of sulfur trioxide in sulfuric acid or sometimes more specifically to pyrosulfuric acid, disulfuric acid. ...

History

Baeyer's original structure for indole, 1869

Indole chemistry began to develop with the study of the dye indigo. This was converted to isatin and then to oxindole. Then, in 1866, Adolf von Baeyer reduced oxindole to indole using zinc dust.^[1] In 1869, he proposed the formula for indole (left) that is accepted today.^[2] Image File history File links Baeyer_indole_structure. ... Image File history File links Baeyer_indole_structure. ... Indigo dye indigo molecule Indigo dye is an important dyestuff with a distinctive blue color (see indigo). ... Isatin or 1H-indole-2,3-dione is a indole derivative. ... Chemical structure of oxindole Oxindole is an aromatic heterocyclic organic compound. ... 1866 (MDCCCLXVI) is a common year starting on Monday of the Gregorian calendar or a common year starting on Wednesday of the 12-day-slower Julian calendar. ... Johann Friedrich Wilhelm Adolf von Baeyer (October 31, 1835 - August 20, 1917) was a German chemist who synthesized indigo, and was the 1905 recipient of the Nobel Prize in Chemistry . ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Appearance bluish pale gray Standard atomic weight 65. ...

Certain indole derivatives were important dyestuffs until the end of the 19th century. In the 1930s, interest in indole intensified when it became known that the indole nucleus is present in many important alkaloids, as well is in tryptophan and auxins, and it remains an active area of research today.^[3] Face The 1930s (years from 1930–1939) were described as an abrupt shift to more radical and conservative lifestyles, as countries were struggling to find a solution to the Great Depression, also known in Europe as the World Depression. ... Chemical structure of ephedrine, a phenethylamine alkaloid An alkaloid is, strictly speaking, a naturally occurring amine produced by a plant,[1] but amines produced by animals and fungi are also called alkaloids. ... Tryptophan is an amino acid and essential in human nutrition. ... IAA appears to be the most active Auxin in plant growth. ...

Synthesis of indoles

Indole is a major constituent of coal-tar, and the 220-260 °C distillation fraction is the main industrial source of the material. Indole and its derivatives can also be synthesized by a variety of methods.^[4][5][6]

Leimgruber-Batcho indole synthesis

The Leimgruber-Batcho indole synthesis is an efficient method of sythesizing indole and substituted indoles. Originally disclosed in a patent in 1976, this method is high-yielding and can generate substituted indoles. This method is especially popular in the pharmaceutical industry, where many pharmaceutical drugs are comprised of specifically substituted indoles. Image File history File links Download high resolution version (1862x482, 9 KB) Description: Reaction scheme of the Leimgruber-Batcho indole synthesis. ... The Leimgruber-Batcho indole synthesis is a series of chemical reactions that produce indoles from o-nitrotoluenes 1. ... Year 1976 (MCMLXXVI) was a leap year starting on Thursday (link will display full calendar) of the 1976 Gregorian calendar. ... This is a list of pharmaceutical and biotech companies that are major manufacturers on global or national markets : Abbott Laboratories Able Laboratories Akzo Nobel Allergan Almirall Prodesfarma Alphapharm Altana (previously Byk Gulden) ALZA, part of Johnson & Johnson Amgen AstraZeneca, formed from the merger of Astra AB and Zeneca Group PLC... It has been suggested that Blockbuster drug be merged into this article or section. ...

Fischer indole synthesis

One of the oldest and most reliable methods for synthesizing substituted indoles is the Fischer indole synthesis developed in 1883 by Emil Fischer. Although the synthesis of indole itself is problematic using the Fischer indole synthesis, it is often used to generate indoles substituted in the 2- and/or 3-positions. Image File history File links Download high resolution version (1199x302, 4 KB) Description: Summary of the Fischer indole synthesis. ... The Fischer indole synthesis is a chemical reaction that produces the aromatic heterocycle indole from a (substituted) phenylhydrazine and an aldehyde or ketone under acidic conditions. ... 1883 (MDCCCLXXXIII) was a common year starting on Monday (see link for calendar). ... Hermann Emil Fischer (October 9, 1852 - July 15, 1919) was a German chemist and recipient of the Nobel Prize for Chemistry in 1902. ...

Other indole forming reactions

• Bartoli indole synthesis
• Bischler-Möhlau indole synthesis
• Gassman indole synthesis
• Hemetsberger indole synthesis
• Larock indole synthesis
• Madelung synthesis
• Nenitzescu indole synthesis
• Reissert indole synthesis
• In the Diels-Reese reaction ^{[7] [8]} dimethyl acetylenedicarboxylate reacts with diphenylhydrazine to an adduct which in xylene gives dimethyl indole-2,3-dicarboxylate and aniline. With other solvents other products are formed: with glacial acetic acid a pyrazolone and with pyridine a quinoline.

The Bartoli indole synthesis (also called the Bartoli reaction) is the chemical reaction of ortho-substituted nitroarenes with vinyl grignard reagents to form substituted indoles. ... The Bischler-Möhlau indole synthesis is a chemical reaction that forms a 2-aryl-indole from a 2-bromo-acetophenone and excess aniline. ... The Gassman indole synthesis is a series of chemical reactions used to synthesize substituted indoles from aniline. ... The Hemetsberger indole synthesis (also called the Hemetsberger-Knittel synthesis) is a chemical reaction that thermally decomposes a 3-aryl-2-azido-propenoic ester into a indole-2-carboxylic ester. ... The Larock indole synthesis is a chemical reaction used to synthesize indoles from ortho-iodoanilines and a disubstituted alkyne. ... The Madelung synthesis is a chemical reaction that produces (substituted or unsubstituted) indoles by the intramolecular cyclization of N-phenylamides using strong base at high temperature. ... The Nenitzescu indole synthesis is a chemical reaction that forms 5-hydroxyindole derivatives from benzoquinone and β-aminocrotonic esters. ... The Reissert indole synthesis is a series of chemical reactions designed to synthesize indole or substituted-indoles from ortho-nitrotoluene 1. ... Dimethyl acetylenedicarboxylate (DMAD) is the organic compound with the formula CH3O2CC2CO2CH3. ... Hydrazine is the chemical compound with formula N2H4. ... The term xylenes refers to a group of 3 benzene derivatives which encompasses ortho-, meta-, and para- isomers of dimethyl benzene. ... Aniline, phenylamine or aminobenzene (C6H5NH2) is an organic chemical compound which is a primary aromatic amine consisting of a benzene ring and an amino group. ... The chemical compound acetic acid (from the Latin word acetum, meaning vinegar), systematically called ethanoic acid, is the acid that gives vinegar its sour taste. ... Pyrazole Phenazone Ampyrone Phenylbutazone Pyrazolone, a five-membered-ring lactam, is a derivative of pyrazole that has an additional keto (=O) group. ... Pyridine is a chemical compound with the formula C5H5N. It is a liquid with a distinctively putrid odour. ... Quinoline, also known as 1-azanaphthalene, 1-benzazine, or benzo[b]pyridine, is a heterocyclic aromatic organic compound. ...

Chemical reactions of indole

Nitrogen basicity

Although the indole N-1 nitrogen atom has a lone pair of electrons, indole is not basic like amines and anilines because the lone pair is delocalised and contributes to the aromatic system. The protonated form has an pK_a of -3.6, so that very strong acids like hydrochloric acid are needed to protonate a substantial amount of indole. The sensitivity of many indolic compounds (e.g., tryptamines) under acidic conditions is caused by this protonation. A lone pair is an electron pair without bonding or sharing with other atoms. ... e- redirects here. ... Acids and bases: Acid-base reaction pH Self-ionization of water Buffer solutions Systematic naming Acid-base extraction Acidity function Proton affinity Acids: Strong acids Weak acids Superacids Lewis acids Mineral acids Organic acids Bases: Strong bases Weak bases Superbases Lewis bases Organic bases edit In chemistry, a base is... The general structure of an amine Amines are organic compounds and a type of functional group that contain nitrogen as the key atom. ... Aniline, phenylamine or aminobenzene (C6H5NH2) is an organic chemical compound which is a primary aromatic amine consisting of a benzene ring and an amino group. ... The acid dissociation constant (Ka), also known as the acidity constant or the acid-ionization constant, is a specific equilibrium constant for the reaction of an acid with its conjugate base in aqueous solution [1]. // When an acid dissolves in water, it partly dissociates forming hydronium ions and its conjugate... The chemical compound hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride gas (HCl). ... Protonation is the addition of a proton (H+) to an atom, molecule, or ion. ... Tryptamine (3-(2-aminoethyl)indole) is a monoamine compound that is widespread in nature. ...

Electrophilic substitution

The most reactive position on indole for electrophilic aromatic substitution is C-3, which is 10¹³ times more reactive than benzene. For example, Vilsmeier-Haack formylation of indole^[9] will take place at room temperature exclusively at C-3. Since the pyrrollic ring is the most reactive portion of indole, nucleophilic substitution of the carbocyclic (benzene) ring can take place only after N-1, C-2, and C-3 are substituted. Electrophilic aromatic substitution or EAS is an organic reaction in which an atom, usually hydrogen, in an aromatic system is replaced by an electrophile. ... Benzene, also known as benzol, is an organic chemical compound with the formula C6H6. ... The Vilsmeier-Haack reaction or Vilsmeier reaction is an organic reaction between a substituted amide and a activated arene in the presence of phosphorus oxychloride. ... A Formylation reaction in organic chemistry is the catch-all name for any organic reaction in which an organic compound is functionalized with a formyl group -CH=0. ...

Gramine, a useful synthetic intermediate, is produced via a Mannich reaction of indole with dimethylamine and formaldehyde. Image File history File links Download high resolution version (1128x436, 5 KB) Description: The Vilsmeyer-Haack formylation of indole. ... Gramine (also called donaxine) is a naturally occuring indole alkaloid present in several plant species. ... The Mannich reaction is a chemical reaction in organic chemistry and is a amino alkylation of an acidic proton placed next to a carbonyl functional group with formaldehyde and ammonia or any primary or secondary amine. ... Safety (MSDS) data for dimethylamine General Synonyms: N-methyl-methanamine Molecular formula: C2H7N CAS No: 124-40-3 EINECS No: 204-697-4 EC index no: 612-001-00-9 Physical data Appearance: colourless gas with strong ammonia-like smell Melting point: -92 C Boiling point: 7. ... The chemical compound formaldehyde (also known as methanal) is a gas with a pungent smell. ...

Image File history File links Download high resolution version (984x419, 4 KB) Description: Formation of gramine. ...

Nitrogen-H acidity and organometallic indole anion complexes

The N-H proton has a pK_a of 21 in DMSO, so that very strong bases like sodium hydride or butyl lithium and water-free conditions are needed for complete deprotonation. Salts of the resulting indole anion can react in two ways. Highly-ionic salts such as the sodium or potassium compounds tend to react with electrophiles at nitrogen-1, whereas the more covalent magnesium compounds (indole Grignard reagents) and (especially) zinc complexes tend to react at carbon-3 (see figure below). For the same reason, polar aprotic solvents such as DMF and DMSO tend to favour attack at the nitrogen, whereas nonpolar solvents such as toluene favour C-3 attack.^[10] Dimethyl sulfoxide (DMSO) is the chemical compound (CH3)2SO. This colorless liquid is an important dipolar aprotic solvent. ... It has been suggested that this article or section be merged into base (chemistry). ... Sodium hydride is a highly flammable, and corrosive chemical compound with formula NaH and CAS number 7646-69-7. ... An organolithium reagent is a carbon nucleophile similar to a Grignard reagent. ... Deprotonation is a chemistry term that refers to the removal of a proton (hydrogen ion H+) from a molecule, forming the conjugate base. ... For other uses, see Salt (disambiguation). ... Electron configurations of lithium and fluorine. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Standard atomic weight 22. ... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Standard atomic weight 39. ... In chemistry, an electrophile (literally electron-lover) is a reagent attracted to electrons that participates in a chemical reaction by accepting an electron pair in order to bond to a nucleophile. ... Covalent bonding is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. ... The Grignard reaction is an organometallic chemical reaction involving alkyl- or aryl-magnesium halides, also called Grignard reagents, with electrophiles. ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Appearance bluish pale gray Standard atomic weight 65. ... The polarity of an object is, in general, its physical alignment of atoms. ... A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ... Dimethylformamide (DMF, N,N-dimethylformamide) is a clear liquid, miscible with water and majority of organic solvents. ... Dimethyl sulfoxide (DMSO) is the chemical compound (CH3)2SO. This colorless liquid is an important dipolar aprotic solvent. ... Toluene, also known as methylbenzene or phenylmethane is a clear, water-insoluble liquid with the typical smell of paint thinners, redolent of the sweet smell of the related compound benzene. ...

Image File history File links Indole_anion_reactions. ...

Carbon acidity and C-2 lithiation

After the N-H proton, the hydrogen at C-2 is the next most acidic proton on indole. Reaction of N-protected indoles with butyl lithium or lithium diisopropylamide results in lithiation exclusively at the C-2 position. This strong nucleophile can then be used as such with other electrophiles. An organolithium reagent is a carbon nucleophile similar to a Grignard reagent. ... Lithium diisopropylamide (LDA), is a strong base, widely used in organic chemistry for the generation of carbanions. ...

Bergman and Venemalm developed a technique for lithiating the 2-position of unsubstituted indole.^[11]

Image File history File links Download high resolution version (1615x320, 6 KB) Description: Reaction scheme of the lithiation of indole at the 2-position. ...

Oxidation of indole

Due to the electron-rich nature of indole, it is easily oxidized. Simple oxidants such as N-bromosuccinimide will selectively oxidize indole 1 to oxindole (4 and 5). Illustration of a redox reaction Redox (shorthand for oxidation/reduction reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ... Flash point None R/S statement R: ? S: ? RTECS number  ? Supplementary data page Structure and properties n, εr, etc. ... Chemical structure of oxindole Oxindole is an aromatic heterocyclic organic compound. ...

Image File history File links Download high resolution version (2540x379, 9 KB) Description: Oxidation of indole with NBS. Author, date of creation: selfmade by ~K, 23 August 2005. ...

Cycloadditions of indole

Only the C-2 to C-3 pi-bond of indole is capable of cycloaddition reactions. Intermolecular cycloadditions are not favorable, whereas intramolecular variants are often high-yielding. For example, Padwa et al.^[12] have developed this Diels-Alder reaction to form advanced strychnine intermediates. In this case, the 2-aminofuran is the diene, whereas the indole is the dienophile. A Cycloaddition is a pericyclic chemical reaction, in which two π bonds are lost and two σ bonds are gained [1] the resulting reaction is a cyclization reaction. ... The Diels-Alder reaction The Diels-Alder reaction is an organic chemical reaction (specifically, a cycloaddition) between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. ... Strychnine (pronounced (British, U.S.), or (U.S.)) is a very toxic (LD50 = 10 mg approx. ... Dienes are hydrocarbons which contain two double bonds. ... A dienophile can only properly be explained by being familar with a Diels-Alder reaction. ...

Indoles also undergo intramolecular [2+3] and [2+2] cycloadditions. Image File history File links Download high resolution version (1045x515, 7 KB) Description: Reaction scheme of a cycloaddition reaction of indole. ...

Applications

Natural jasmine oil, used in the perfume industry, contains around 2.5% of indole. Since 1 kilogram of the natural oil requires processing several million jasmine blossoms and costs around $10,000, indole (among other things) is used in the manufacture of synthetic jasmine oil (which costs around $10/kg). Jasminum. ... An essential oil is a concentrated, hydrophobic liquid containing volatile aromatic compounds from plants. ... Perfume is a mixture of fragrant essential oils and aroma compounds, fixatives, and solvents used to give the human body, objects, and living spaces a pleasant smell. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et...

See also

• Martinet dioxindole synthesis
• Skatole (3-methylindole)
• Stollé synthesis
• Tryptamines
• Jenkem

The Martinet dioxindole synthesis is a chemical reaction used to synthesize dioxindoles 3 from anilines and esters of mesoxalic acid 1. ... Skatole or 3-methylindole is a mildly toxic white crystalline organic compound with chemical formula C9H9N and CAS number 83-34-1. ... The Stollé synthesis is a series of chemical reactions that produce oxindoles from anilines and α-haloacid chlorides (or oxalyl chloride). ... Tryptamine (3-(2-aminoethyl)indole) is a monoamine compound that is widespread in nature. ... Jenkem or jekem is an inhaled gas which can result in dissociation and hallucinations. ...

General references

• Indoles Part One, W. J. Houlihan (ed.), Wiley Interscience, New York, 1972.
• Sundberg, R. J. (1996). Indoles. San Diego: Academic Press. ISBN 0-12-676945-1. 
• Joule, J. A.; Mills, K. (2000). Heterocyclic Chemistry. Oxford, UK: Blackwell Science. ISBN 0-632-05453-0. 
• Joule, J., In Science of Synthesis, Thomas, E. J., Ed.; Thieme: Stuttgart, (2000); Vol. 10, p. 361. ISBN 3-13-112241-2 (GTV); ISBN 0-86577-949-X (TNY).

References

Johann Friedrich Wilhelm Adolf von Baeyer (October 31, 1835 - August 20, 1917) was a German chemist who synthesized indigo, and was the 1905 recipient of the Nobel Prize in Chemistry . ... Johann Friedrich Wilhelm Adolf von Baeyer (October 31, 1835 - August 20, 1917) was a German chemist who synthesized indigo, and was the 1905 recipient of the Nobel Prize in Chemistry . ... Chemische Berichte (usually abbreviated as or ) is a German-language scientific journal featuring chemistry of all disciplines. ... Chemical Reviews (usually abbreviated as ), is a peer-reviewed scientific journal, published since 1900 by the American Chemical Society. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Chemical Reviews (usually abbreviated as ), is a peer-reviewed scientific journal, published since 1900 by the American Chemical Society. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Chemical Reviews (usually abbreviated as ), is a peer-reviewed scientific journal, published since 1900 by the American Chemical Society. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... The Journal of the American Chemical Society (usually abbreviated as , or JACS), is a peer-reviewed scientific journal, published since 1879 by the American Chemical Society. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Organic Syntheses is a scientific journal that Since 1921 has provided the chemistry community with annual collections of detailed and checked procedures for the organic synthesis of organic compounds. ... Organic Syntheses is a scientific journal that Since 1921 has provided the chemistry community with annual collections of detailed and checked procedures for the organic synthesis of organic compounds. ... The Journal of Organic Chemistry (abbreviated as ) is a scientific journal for original contributions of fundamental research in organic and bioorganic chemistry. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Organic Letters (usually abbreviated as ), is a peer-reviewed scientific journal, published since 1999 by the American Chemical Society. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

External links

• Synthesis and reactivity of indoles
• Synthesis of indoles (overview of recent methods)

• Links to external chemical sources