Name | Indole |
Synonyms | Indole INDOLE IndoleGr 1H-Indole FEMA 2593 Indole-15N 1-Azaindene BENZO(B)PYRROLE 2,3-Benzopyrrole INDOLE CRYSTALLINE GR Indole, (1-Benzazole) 2,3-Benzopyrrole,OrBenzazole,Indole |
CAS | 120-72-9 |
EINECS | 204-420-7 |
InChI | InChI=1/C8H7N/c1-2-4-8-7(3-1)5-6-9-8/h1-6,9H |
Molecular Formula | C8H7N |
Molar Mass | 117.15 |
Density | 1.22 |
Melting Point | 51-54 °C (lit.) |
Boling Point | 253-254 °C (lit.) |
Flash Point | >230°F |
JECFA Number | 1301 |
Water Solubility | 2.80 g/L (25 ºC) |
Solubility | methanol: 0.1g/mL, clear |
Vapor Presure | 0.016 hPa (25 °C) |
Appearance | White crystal |
Color | White to slightly pink |
Odor | fecal odor, floralin high dilution |
Merck | 14,4963 |
BRN | 107693 |
pKa | 3.17 (quoted, Sangster, 1989) |
PH | 5.9 (1000g/l, H2O, 20℃) |
Storage Condition | 2-8°C |
Stability | Stable, but may be light or air sensitive. Incompatible with strong oxidizing agents, iron and iron salts. |
Sensitive | Light Sensitive |
Refractive Index | 1.6300 |
MDL | MFCD00005607 |
Physical and Chemical Properties | White or fine powder red powder Crystal, there is a bad smell. |
Use | Used as a reagent for the determination of nitrite, also used in the manufacture of spices and medicines |
Risk Codes | R21/22 - Harmful in contact with skin and if swallowed. R37/38 - Irritating to respiratory system and skin. R41 - Risk of serious damage to eyes R50/53 - Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. R36 - Irritating to the eyes R39/23/24/25 - R23/24/25 - Toxic by inhalation, in contact with skin and if swallowed. R52/53 - Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment. |
Safety Description | S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S60 - This material and its container must be disposed of as hazardous waste. S61 - Avoid release to the environment. Refer to special instructions / safety data sheets. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S36/37 - Wear suitable protective clothing and gloves. |
UN IDs | UN 2811 6.1/PG 3 |
WGK Germany | 1 |
RTECS | NL2450000 |
FLUKA BRAND F CODES | 8-13 |
TSCA | Yes |
HS Code | 2933 99 20 |
Hazard Class | 9 |
Packing Group | III |
Toxicity | LD50 orally in rats: 1 g/kg (Smyth) |
Downstream Products | 5-Cyanoindole 1,3,3-trimethyl-2-methyleneindoline |
Reference Show more | 1. [IF=3.738] Shanshan Zhang et al."Indole reduces the expression of virulence related genes in Vibrio splendidus pathogenic to sea cucumber Apostichopus japonicus."Microb Pathogenesis. 2017 Oct;111:168 2. [IF=6.576] Huajie Wang et al."Assessment of Variations in Round Green Tea Volatile Metabolites During Manufacturing and Effect of Second-Drying Temperature via Nontargeted Metabolomic Analysis."Frontiers in Nutrition. 2022; 9: 877132 3. [IF=7.514] Chen-Yang Shao et al."Aromatic Profiles and Enantiomeric Distributions of Chiral Odorants in Baked Green Teas with Different Picking Tenderness."Food Chem. 2022 Apr;:132969 |
There are many methods for the production of indole.
FEMA | 2593 | INDOLE |
olfactory threshold (Odor Threshold) | 0.0003ppm |
LogP | 2.14-2.24 |
NIST chemical information | Information provided by: webbook.nist.gov (external link) |
EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
Properties | Indole is also called "azazindine". Molecular formula C8H7N. Molecular weight 117.15. It is found in dung, coal tar, jasmine oil and neroli oil. Colorless leafy or tabular crystals. There is a strong smell of dung, and the pure product has a fresh flower fragrance after dilution. Melting point 52 ℃. Boiling point 253~254 ℃. Soluble in hot water, benzene and petroleum, easily soluble in ethanol, ether and methanol. It can volatilize with water vapor, be placed in the air or turn red with light, and resin. It is weakly acidic, and forms a salt with alkali metals, and reacts with acid to resin or polymerize. The highly diluted solution has jasmine fragrance and can be used as a spice. Compounds of pyrrole in parallel with benzene. Also known as benzopyrrole. There are two ways of merging, called indole and isoindole. Indole and its homologs and derivatives widely exist in nature, mainly in natural flower oil, such as jasmine, orange blossom, daffodil, fragrant roland, etc. Tryptophan, an essential amino acid of animals, is a derivative of indole; some natural substances with strong physiological activity, such as alkaloids and auxin, are all derivatives of indole. Feces contain 3-methylindole. |
Aromatic heterocyclic organic compound | Indole is an aromatic heterocyclic organic compound with a bicyclic structure in the chemical structure, including a six-membered benzene ring and a five-membered nitrogen-containing pyrrole ring, so it is also called benzopyrrole. Because the lone pair of electrons of nitrogen participates in the formation of aromatic rings, indole is not a base, and its properties are different from simple amines. It is an imine with weak basicity; the double bonds of heterocyclic rings generally do not undergo addition reactions; Under the action of strong acids, dimerization and trimerization can occur; under special conditions, aromatic electrophilic substitution reactions can be carried out, and the hydrogen at the 3 position is preferentially replaced, if reacted with sulfonyl chloride, 3-chloroindole can be obtained. A variety of reactions can also occur at the 3 position, such as the formation of Grignard reagents, condensation with aldehydes, and Mannich reactions. Indole is an important organic raw material and fine chemical products. Its homologs and derivatives are widely found in nature, mainly in natural flower oil, such as jasmine, sweet orange, white lemon, pomelo peel, citrus, bitter orange flower, daffodil, fragrant Roland, etc. It can be widely used in the manufacture of jasmine, lilac, orange blossom, gardenia, honeysuckle, lotus, narcissus, ylang ylang, grass orchid, white orchid and other floral flavors. It is also often shared with methindole to prepare artificial civet incense. A very small amount can be used in chocolate, Rubus, Strawberry, bitter orange, coffee, nuts, cheese, grapes and fruity compound flavors. Indole structures can be found in many organic compounds, such as an essential amino acid tryptophan and tryptophan-containing protein in animals, auxin (indole -3-acetic acid), anti-inflammatory drug indomethacin (Indene Methyl), vasodilator drug Xinle, alkaloids and pigments also contain indole structures. Indole alkaloids are natural alkaloids that exist widely in nature, it has a wide range of biological activities such as antibacterial, antitumor and antiviral. The name indole indole is composed of indigo (indigo dye) and oleum (fuming sulfuric acid), because indole was first prepared by mixing indigo and fuming sulfuric acid. One-step synthesis of indole from aniline and ethylene glycol is the most economical one among many synthesis methods. |
use | mainly used as raw materials for spices, dyes, amino acids and pesticides. Indole itself is also a kind of spice. It is often used in daily flavor formulas such as jasmine, lilac, lotus and orchid. The dosage is generally a few thousandths. GB 27 60-96 stipulates that edible spices are allowed to be used. It is mainly used to prepare cheese, citrus, coffee, nuts, grapes, strawberries, raspberries, chocolate, assorted fruits, jasmine and lilies. It is used as a reagent for the determination of nitrite, and is also used in the manufacture of spices and medicines It is a raw material for spices, medicines, and plant growth hormone medicines Indole is a plant growth regulator indole acetic acid, Indole butyric acid intermediates. can be widely used in jasmine, lilac, orange blossom, gardenia, honeysuckle, lotus, narcissus, ylang ylang, grass orchid, white orchid and other flower flavor. It is also often shared with methindole to prepare artificial civet incense. A very small amount can be used in chocolate, Rubus, Strawberry, bitter orange, coffee, nuts, cheese, grapes and fruity compound flavors. Indole is mainly used as a raw material for spices, dyes, amino acids, and pesticides. Indole itself is also a kind of spice. It is often used in daily flavor formulas such as jasmine, lilac, lotus and orchid, and the dosage is generally a few thousandths. Verification of gold, potassium and nitrite to produce jasmine-type spices. Pharmaceutical industry. |
content analysis | determined by polar column method in GT-10-4 gas chromatography. |
toxicity | GRAS(FEMA). LD50 1000 mg/kg (rat, oral). |
usage limit | FEMAmg/kg: soft drink 0.26; Cold drink 0.28; Candy 0.50; Baked food 0.58; Pudding 0.02~0.40. Moderate limit (FDA § 172.515,2000). |
production methods | indole has many production methods. 1. Extracted from wash oil fraction in high temperature coal tar, containing about indole 0.10%-0.16%. Generally, it can be extracted from coal tar and wash oil fractions. The wash oil fraction is subjected to alkali washing and acid washing to obtain methyl naphthalene fraction, which is then rectified in a high-efficiency tower of 60 theoretical plates, cut out the 225-256 ℃ fraction, and add potassium hydroxide to melt. The reaction was carried out at 170-240 ℃ for 2-4h and stirred until bubbling stopped. Let it stand, release the lower layer of indole potassium to cool, break it and wash it with benzene at low temperature to remove oil. Then hydrolyze at 50-70 degrees C to obtain crude indole oil, which is distilled in a distillation tower of 20 theoretical plates, taking the reflux ratio of 8-10:1, cutting the top temperature of the tower 170-256 degrees C fraction, cooling, crystallization, centrifugal filtration, that is, refined indole. After pressing, the oil content is below 3%, and recrystallized with ethanol to obtain refined indole with a purity of 99%. 2. Prepared by catalytic dehydrogenation of o-aminoethylbenzene. O-aminoethylbenzene is dehydrocyclized at 550°C in the presence of aluminum nitrate (or aluminum trioxide) in a nitrogen stream, and is distilled under reduced pressure to obtain indole. Dehydrogenated at 640°C to obtain indole. Other preparation methods include the reaction of o-nitrotoluene and oxalate to generate o-nitrophenylpyruvate and then make α-indole carboxylic acid, and finally dry distillation with lime to obtain the product; aniline and acetylene are heated at 600-650 ℃ to synthesize indole; o-carboxyphenylglycine is synthesized into indole by 3-hydroxy-2-indole carboxylic acid and indole; oxidized with concentrated nitric acid or chromic acid to obtain indolone, the latter is distilled with zinc powder to obtain indole. Mixing nitrocinnamic acid with 10 parts of potassium hydroxide powder, adding iron filings and heating to melt the mixture to obtain indole. The Fischer synthesis method is the most universal for the synthesis of indole and its homologs. The aromatic hydrazone of ketones or aldehydes acts under acidic conditions and undergoes a rearrangement reaction similar to benzidine to form indole. It is obtained by reduction of 3-hydroxyindole, 3-hydroxy-2-hydroxyindole or indigo. It is separated from the 220~260 ℃ fraction of coal tar. |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |