INDOLE
Indole
CAS: 120-72-9
Molecular Formula: C8H7N
INDOLE - Names and Identifiers
| 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 |
INDOLE - Physico-chemical Properties
| 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 |
INDOLE - Risk and Safety
| 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) |
INDOLE - Upstream Downstream Industry
| Downstream Products | 5-Cyanoindole 1,3,3-trimethyl-2-methyleneindoline |
INDOLE - Reference
| 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 |
INDOLE - Nature
Open Data Verified Data
- colorless crystals with strong fecal odor. Melting point 52.5 ℃, boiling point 254 ℃,128~133 ℃(3. 7kPa), the relative density of 1.22. Soluble in hot water, benzene and petroleum, soluble in ethanol, ether and toluene. Can be volatile with water vapor, placed in the air or see the light to red, and resin. Highly diluted solution can be used as a fragrance.
- indole and its homologs and derivatives widely exist in nature, originally from Indigo degradation; Indole and its homologs also exist in coal tar; Essential oils (such as Jasmine essential oil, etc.) also contains Indole; Feces contain 3 methyl indole; Many vat dyes are derivatives of indole; An essential amino acid tryptophan is a derivative of indole, many indole derivatives in the body are derived from it; Some natural substances with strong physiological activity, such as alkaloids, auxin, etc., are derivatives of indole.
Last Update：2025-06-10 22:55:16
INDOLE - Preparation Method
Open Data Verified Data
There are many methods for the production of indole.
- extraction from wash oil fraction in high temperature coal tar, about 0.1 ~ 0.16% of indole is contained. It is generally extracted from the wash oil fraction of coal tar. The wash oil fraction was subjected to alkali washing and acid washing to obtain methyl naphthalene fraction. Then, the fraction was rectified in a high efficiency column of 60 theoretical trays, cut out a fraction section at 225-256 ° C., and melted with potassium hydroxide to obtain potassium indole.
- synthesis is obtained by catalytic dehydrogenation of O-aminoethylbenzene.
- other methods (1) by O-nitrotoluene and Oxalate Reaction to generate O-nitrophenyl pyruvate, and then made into a-indole carboxylic acid, and finally dry distillation with lime to obtain products;(2) indole was synthesized from aniline and acetylene at 600~650 ℃;(3) indole was synthesized from O-carboxyphenylglycine via 3-hydroxy-2-indole carboxylic acid and indole acid;(4) Indole can be obtained by oxidizing indigo blue with concentrated nitric acid or chromic acid, and the latter can be distilled with zinc powder to obtain indole; Mix the mixed nitrocinnamic acid with 10 minutes of potassium hydroxide powder, and add iron chips, the Indole can also be obtained by melting the mixture by heating.
Last Update：2022-01-01 10:53:43
INDOLE - Introduction
It stinks in dung, but has a pleasant fragrance when diluted. It has a strong smell of dung, highly diluted solution has fragrance, and turns red when exposed to air and light. Can volatilize with water vapor. Soluble in hot water, hot ethanol, ether, benzene and petroleum ether.
Last Update：2022-10-16 17:12:33
INDOLE - Application
Open Data Verified Data
- indole is mainly used as a raw material for spices, dyes, amino acids, and pesticides. Indole itself is also a kind of spice, commonly used in Jasmine, clove, Lotus and orchid and other daily flavor formula, the dosage is generally a few parts per thousand. Some of the indole derivatives are dyes, auxins, and pharmaceuticals. In the dye industry, can be used for the synthesis of sulfur dyes, indigo dyes, can also be used instead of aniline synthesis of 1,3,5 A three methyl methylene indole.
- some European manufacturers use indole to produce tryptophan, which is used for amino acid infusion or as a feed additive. Compared with lysine and methionine, tryptophan is required in much less quantity, but its importance is not inferior. Corn Feed, lysine, methionine, tryptophan content is low, the current world corn production of about 0.4 billion tons, if added 0. 7% lysine, 0.3 methionine, 0.1% tryptophan, the demand is 2.8 million tons, 140,000 tons and 400,000 tons respectively.
- indole is also used in the synthesis of plant growth regulators, such as indole acetic acid and indole butyric acid, etc., it is reported that indole acetonitrile (indole acetonitrile) is used as a plant growth hormone, its use effect is 10 times that of indole acetic acid.
Last Update：2025-08-19 16:24:40
INDOLE - Safety
Open Data Verified Data
- indole-large lOOOmg/kg, which has been reported to induce tumor growth in rats.
- cardboard or iron drum packaging, 25kg/barrel. Mouse oral LD50 indole auxin plastic bag lining.
Last Update：2022-01-01 10:53:43
INDOLE - Reference Information
| 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) |
Last Update：2024-04-09 20:49:11
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