3D Mol Similar

Indigo

: Iupac Name：(2E)-2-(3-oxo-1H-indol-2-ylidene)-1H-indol-3-one; CAS No.: 482-89-3; Molecular Weight：262.268; Modify Date.: 2022-11-29 12:17; Introduction: Indigo, known chemically as indigotin, is a common blue dye that has been highly valuedthroughout history and has played a major role in trade and commerce since ancient times.The term indigo is often used to describe many blue dyes produced from a number of plants.For example, woad, a blue dye obtained from the plant Isatis tinctoria, was used throughoutthe Mediterannean and Europe and is often identified as indigo. True indigo comes fromthe leguminous plant of the genus Indigofera. The Indigofera genus includes several hundredspecies, and indigo has been obtained from a number of these, but the dominant species forthe dye are Indigofera tinctoria grown mainly in India and tropical Asia and Indigofera suff ructiosafrom the tropical Americas. The name indigo comes from the Greek indikon and Latinindicum meaning “dye from India.” There is evidence that indigo was used several thou sandyears b.c.e. Persian rugs containing indigo color exist from several thousand years b.c.e. Textileartifacts from Egyptian tombs provide evidence of indigo’s use by royalty from as far back as2500 b.c.e. The writings of Herodotus from approximately 450 b.c.e. mention indigo’s use inthe Mediterranean area. View more+

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1. Names and Identifiers

: 1.1 Name; Indigo; 1.2 Synonyms; (2,2’-biindoline)-3,3’-dione (2,2'-Biindoline)-3,3'-dione (2E)-2-(3-Oxo-1,3-dihydro-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one (delta(2,2’(3h,3’h))-biindole)-3,3’-dione (delta(2,2’)-biindoline)-3,3’-dione [D2,2'-Biindoline]-3,3'-dione [Δ2,2'-Biindoline]-3,3'-dione 3H-Indol-3-one, 2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-, (2E)- AO201 Blue No 201 C.I. Natural Blue 1 C.I. Pigment Blue 66 d&cblueno.6 D+C Blue No. 6 d+cblueno6 D2,2'-Bipseudoindoxyl EINECS 207-586-9 indigo Blue Indigo J indigo powder indigon Indigotin indigovs MFCD00005722 PIGMENT BLUE 66 trans-indigo Vat Dark Blue VB Δ2,2'-Bipseudoindoxyl; View all

1.3 CAS No.: 482-89-3

1.4 CID: 10215

1.5 EINECS(EC#): 207-586-9

1.6 Molecular Formula: C16H10N2O2 (isomer)

1.7 Inchi: InChI=1S/C16H10N2O2/c19-15-9-5-1-3-7-11(9)17-13(15)14-16(20)10-6-2-4-8-12(10)18-14/h1-8,17,19H

1.8 InChIkey: QQILFGKZUJYXGS-UHFFFAOYSA-N

1.9 Canonical Smiles: C1=CC=C2C(=C1)C(=C(N2)C3=NC4=CC=CC=C4C3=O)O

1.10 Isomers Smiles: C1=CC=C2C(=C1)C(=C(N2)C3=NC4=CC=CC=C4C3=O)O

2. Properties

2.1 Density: 1.417

2.1 Melting point: 390-392℃ (dec.)

2.1 Boiling point: 400.4°Cat760mmHg

2.1 Refractive index: 1.709

2.1 Flash Point: 158.2°C

2.1 Precise Quality: 262.07400

2.1 PSA: 58.20000

2.1 logP: 3.09080

2.1 Solubility: <0.1 g/100 mL

2.2 Λmax: 603(CHCl3)nm

2.3 AnalyticLaboratory Methods: COLUMN CHROMATOGRAPHIC-SPECTROPHOTOMETRIC DETERMINATION OF INDIGO IN CHINESE TRADITIONAL MEDICINE QING-DAI PREPD FROM LEAF OR STEM OF ISATIS TINCTORIA, BAPHICACANTHES CUSIA, INDIOFERA SUFFRUICOSA OR POLYGONUM TINCTORUM.

2.4 Appearance: C.i. vat blue 1 is a dark blue powder with coppery luster. Occurs in isomeric forms (cis and trans). In solid state it is in the trans form. (NTP, 1992)

2.5 Color/Form: DARK-BLUE POWDER WITH COPPERY LUSTER

2.6 Physical: PHYSICAL DESCRIPTION: Dark blue powder with coppery luster. Occurs in isomeric forms (cis and trans). In solid state it is in the trans form. (NTP, 1992)

2.7 pKa: -3.83±0.20(Predicted)

2.8 Water Solubility: SOL IN ANILINE, NITROBENZENE, CHLOROFORM, GLACIAL ACETIC ACID, CONCN SULFURIC ACID

2.9 Spectral Properties: IR: 1620 (Coblentz Society Spectral Collection)
UV: 3-558 (Organic Electronic Spectral Data, Phillips et al, John Wiley & Sons, New York)

2.10 Stability: Stable. Incompatible with strong oxidizing agents.

2.11 StorageTemp: Keep container closed when not in use. Store in a cool, dry, well-ventilated area away from incompatible substances.

3. Use and Manufacturing

3.1 Definition: A double indole derivative.

3.2 General Description: Dark blue powder with coppery luster. Occurs in isomeric forms (cis and trans). In solid state Indigo is in the trans form.

3.3 GHS Classification: Signal: Warning
GHS Hazard Statements
Aggregated GHS information provided by 49 companies from 7 notifications to the ECHA C&L Inventory.

Reported as not meeting GHS hazard criteria by 9 of 49 companies. For more detailed information, please visit ECHA C&L website

Of the 6 notification(s) provided by 40 of 49 companies with hazard statement code(s):

H373 (90%): Causes damage to organs through prolonged or repeated exposure [Warning Specific target organ toxicity, repeated exposure]

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown.

Precautionary Statement Codes
P260, P314, and P501; View all

3.4 History: Indigotin. The blue dye of the ancient world was derived from indigo and woad. Which plant is the oldest is a matter of conjecture. That indigo was known at least four thousand years ago is evident from ancient Sanskrit writings. Cloth dyed with indigotin (CI Natural Blue; CI 75780) has been found in Egyptian tombs and in the graves of the Incas in South America. Indigo belongs to the legume family. The two most important species are Indigo tinctoria and I. suffruticosa, found in India and the Americas, respectively. The leaves of the indigo plant do not contain the dye as such, but in the form of its precursor, a glycoside known as indican.

3.5 Methods of Manufacturing: FIRST SYNTHESIS: BAEYER, BER 11: 1296 (1878); 12: 456 (1879). FIRST COMMERCIAL PROCESS: HEUMANN, BER 23: 3043, 3431 (1890).|HARLEY-MASON, J CHEM SOC 1950, 2907; ZIEGLER, KAPPE, MONATSH 96: 889 (1965).|FROM ANILINE & CHLOROACETIC ACID, & FUSING RESULTING PHENYLGLYCINE WITH ALKALI & SODIUM AMIDE. FORMERLY FROM PLANTS OF GENUS INDIGOFERA.|Condensation of aniline, formaldehyde, and hydrocyanic acid to form N-phenylglycinonitrile, followed by alkaline hydrolysis to yield N-phenylglycine which gives indigo in 94% yields. This is the major commercial route used throughout the world

3.6 Purification Methods: First reduce indigo in alkaline solution with sodium hydrosulfite, and filter. The filtrate is then oxidised by air, and the resulting precipitate is filtered off, dried at 65-70o, ground to a fine powder, and extracted with CHCl3 in a Soxhlet extractor. Evaporation of the CHCl3 extract gives the purified dye. [Brode et al. J Am Chem Soc 76 1034 1954; spectral characteristics are listed, Beilstein 24 II 233, 24 III/IV 1791.] Indigo Preparation Products And Raw materials Raw materials

3.7 Usage: 1. It can be used as food coloring agent with the provisions of China being able to be used in red and green silk and the maximum usage amount of 0.02g/kg; it can be used in the juice (flavor) beverages, carbonated beverages, wine, candy, pastry coloring, dyeing cherry can decorative) and green plum with the maximum usage amount of 0.10g/kg; the maximal usage amount in the dipping pickles of 0.01g/kg.2. It is mainly used for the dyeing of cotton yarn, cotton, wool or silk. 3. Reduced indigo is mainly used for dyeing cotton yarn and cotton cloth, being the major dye for blue dye denim. It is also used for wool, silk dyeing and as food coloring and organic pigments.4. Edible blue pigment;5. It is mainly used for dyeing cotton yarn, cotton cloth, wool or silk. Pure product can be used for the manufacturing of food dyes, or processed into organic pigments.

4. Safety and Handling

4.1 Symbol: GHS08

4.1 Hazard Codes: Xi

4.1 Signal Word: Warning

4.1 Risk Statements: R36/37/38

4.1 Safety Statements: S26;S36

4.1 Exposure Standards and Regulations: D & C BLUE NO 6 (INDIGO) MAY BE USED UNDER FEDERAL FOOD, DRUG, & COSMETIC ACT IN COLORING POLY(ETHYLENE TEREPHTHALATE) NONABSORBABLE SUTURES FOR USE IN GENERAL & OPHTHALMIC SURGERY. SPECIFICATIONS FOR CERTIFICATION ARE GIVEN.

4.2 Packing Group: I

4.2 Fire Hazard: Flash point data for Indigo are not available but Indigo is probably combustible.

4.3 Hazard Declaration: H373

4.3 Cleanup Methods: INDIGO IS RECOVERED FROM WASTEWATER CONTAINING 0.1 KG/CU M BY FLOCCULATION WITH 0.03 KG/CU M CACL2-MGCL2 & 2.3 KG/CU M NAOH.
WASTEWATER FROM INDIGO DYEING IS FILTERED AT 62 L/MIN ON STAINLESS STEEL SCREEN (128 MESH/CM) & CONCN 100-FOLD BY REVERSE OSMOSIS AT 4.75 M/SEC & 65 DEG/69 BAR THROUGH POROUS STAINLESS STEEL TUBES TO GIVE 4600 L/SQ M/DAY EFFLUENT.

4.4 RIDADR: 50kgs

4.4 Safety Profile: Mutation data reported. Whenheated to decomposition it emits toxic vapors of NOx.

4.5 Caution Statement: P260

4.5 Formulations/Preparations: GRADES: TECHNICAL; PURE

4.6 WGK Germany: 1

4.6 RTECS: DU2988400

4.6 Report: Reported in EPA TSCA Inventory.

4.7 Safety: Hazard Codes:Xi
Risk Statements:36/38-36/37/38
36/38:Irritating to eyes and skin
36/37/38:Irritating to eyes, respiratory system and skin
Safety Statements:26-36
26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice
36:Wear suitable protective clothing
RIDADR:UN 3264 8/PG 3
WGK Germany:1
Hazardous Substances Data:482-89-3(Hazardous Substances Data)

4.8 Specification

The Indigo with the cas number 482-89-3, is also called (2E)-2-(3-oxo-1H-indol-2-ylidene)-1H-indol-3-one named by IUPAC. And it's systemic name are(1)(delta(sup 2,2')-Biindoline)-3,3'-dione; (2)(delta2,2'-Biindoline)-3,3'-dione (8CI) ; (3)2-(1,3-Dihydro-3-oxo-2H-indazol-2-ylidene)-1,2-dihydro-3H-indol-3-one ; (4)2-(1,3-Dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one ; (5)3H-Indol-3-one, 2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-. It belongs to rganics product categories. Besides, it seems like dark blue powder with coppery luster. Indigo occurs in isomeric forms (cis and trans). It is Stable but incompatible with strong oxidizing agents. Water solubility is lower than other edible pigment around 25 ° c. 0.05% solution appears blue. It is soluble in glycerin, propylene glycol, slightly soluble in ethanol, insoluble in grease. It shows darkblue when encounter sulfuric acid, and appear to be blue when diluted. with sodium hydroxide in solution, it turns green and yellow green. And it is sensitive to heat and light. Indigo? is used as a dye for cotton yarn, which is mainly for the production of denim cloth for blue jeans. Small amounts are used for dying wool and silk.

Physical properties about this chemical are: (1)ACD/LogP: 3.72 ; (2)# of Rule of 5 Violations: 0 ; (3)ACD/LogD (pH 5.5): 3.72 ; (4)ACD/LogD (pH 7.4): 3.72 ; (5)ACD/BCF (pH 5.5): 395.55 ; (6)ACD/BCF (pH 7.4): 395.55 ; (7)ACD/KOC (pH 5.5): 2515.82 ; (8)ACD/KOC (pH 7.4): 2515.82 ; (9)#H bond acceptors: 4 ; (10)#H bond donors: 2 ; (11)#Freely Rotating Bonds: 0 ; (12)Polar Surface Area: 40.62?² ; (13)Index of Refraction: 1.709 ; (14)Molar Refractivity: 72.22 cm³ ; (15)Molar Volume: 185 cm³ ; (16)Polarizability: 28.63 ×10^-24cm³ ; (17)Surface Tension: 63.4 dyne/cm ; (18)Density: 1.417 g/cm³ ; (19)Flash Point: 158.2 °C ; (20)Enthalpy of Vaporization: 65.13 kJ/mol ; (21)Boiling Point: 400.4 °C at 760 mmHg ; (22)Vapour Pressure: 1.27E-06 mmHg at 25°C

Prepration of Indigo: Indigo powder sulfonation by sulfuric acid, diluted by water, neutralization with sodium carbonate, refined by salting-out. Indigo powder (100%) 210kg can be produced at the cost of every tons product. It is an synthesis edible pigment and applied to food, medicine and cosmetics.

1. N-phenylglycine is treated with a molten mixture of sodium hydroxide, potassium hydroxide, and sodamide. This highly sensitive melt produces indoxyl, which is subsequently oxidised in air to form indigo.

2. An alternative and also viable route to indigo involves heating N-(2-carboxyphenyl)glycine to 200 °C in an inert atmosphere with sodium hydroxide. Indoxyl-2-carboxylic acid is generated. This material readily decarboxylates to give indoxyl, which oxidises in air to form indigo.

When you are using this chemical, please be cautious about it as the following: It is quite irritating to eyes, respiratory system and skin. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.?Before you are using it, please wear suitable protective clothing. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.?

You can still convert the following datas into molecular structure :
(1).SMILES: O=C/4c1ccccc1NC\4=C3\C(=O)c2ccccc2N3
(2).InChI:InChI=1/C16H10N2O2/c19-15-9-5-1-3-7-11(9)17-13(15)14-16(20)10-6-2-4-8-12(10)18-14/h1-8,17-18H/b14-13+

Toxic information of Indigo can be showed as follows:

Organism	Test Type	Route	Reported Dose (Normalized Dose)	Effect	Source
mouse	LD50	intraperitoneal	2200mg/kg (2200mg/kg)	?	"Zhongliu Yanjiu" Cancer Review, Yu, R., et al., eds., Shanghai Science/Technology Publisher,Peop. Rep. China, 1994Vol. -, Pg. 173, 1994.
mouse	LD50	oral	> 32gm/kg (32000mg/kg)	?	"Zhongliu Yanjiu" Cancer Review, Yu, R., et al., eds., Shanghai Science/Technology Publisher,Peop. Rep. China, 1994Vol. -, Pg. 173, 1994

View all

4.9 Toxicity: LD50 oral in mouse: > 32gm/kg

5. MSDS

2.Hazard identification

2.1 Classification of the substance or mixture

Specific target organ toxicity \u2013 repeated exposure, Category 2

2.2 GHS label elements, including precautionary statements

Pictogram(s)
Signal word	Warning
Hazard statement(s)	H373 May cause damage to organs through prolonged or repeated exposure
Precautionary statement(s)
Prevention	P260 Do not breathe dust/fume/gas/mist/vapours/spray.
Response	P314 Get medical advice/attention if you feel unwell.
Storage	none
Disposal	P501 Dispose of contents/container to ...

2.3 Other hazards which do not result in classification

none

6. NMR Spectrum

Mass spectrum (electron ionization)

7. Synthesis Route

482-89-3Total: 153 Synthesis Route

91-56-5 207 Suppliers

482-89-3 198 Suppliers

Literatures:
Bergman, Jan; Stlhandske, Claes Tetrahedron Letters, 1994 , vol. 35, # 29 p. 5279 - 5282
Yield: ~91%

612-54-4 3 Suppliers

482-89-3 198 Suppliers

Literatures:
Katritzky, Alan R.; Fan, Wei-Qiang; Koziol, Anna E.; Palenik, Gus J. Journal of Heterocyclic Chemistry, 1989 , vol. 26, p. 821 - 828
Yield: ~70%

552-89-6 290 Suppliers

482-89-3 198 Suppliers

Literatures:
Baudisch Biochemische Zeitschrift, 1918 , vol. 89, p. 280
Yield: null

View all

8. Precursor and Product

precursor:

577-59-3

612-42-0

771-50-6

120-72-9

612-54-4

552-89-6

612-41-9

91-56-5

122-57-6

610-14-0

610-33-3

586-96-9

608-08-2

480-93-3

551-93-9

530-85-8

119-68-6

103-01-5

View all

product :

40899-99-8

6374-92-1

2475-31-2

15206-55-0

617-48-1

118-48-9

615-57-6

6537-68-4

605-18-5

69423-26-3

894-86-0

874-17-9

2903-89-1

138574-86-4

480-93-3

172984-51-9

6374-91-0

88-06-2

1768-31-6

38505-89-4

552-89-6

479-41-4

87-69-4

87-48-9

172950-81-1

6417-56-7

View all

9. Other Information

9.0 Chemical properties: It appears as blue powder, being odorless and slightly soluble in water, ethanol, glycerol and propylene glycol, insoluble in oil. At 25 ℃, the solubility is 1.6% (water), 0.5% (25% ethanol), 0.6% (25% propylene glycol). The 0.05% aqueous solution exhibits dark blue. It has poor performance on all the following aspects: light resistance, heat resistance, acid resistance, alkali resistance, salt tolerance, oxidation resistance and resistance to bacteria. Upon reduction, the color will fade, but the dye is good. The maximum absorption wavelength (610 ± 2) nm. Rat oral LD50: 2g/kg, mice oral LD50 2.5g/kg, ADI 0-5mg/kg (FAO/WHO, 1994).
Indigo Aluminum precipitate is a fine powder with violet blue color, being odorless. It can’t dissolve in water and organic solvents with better light resistance and heat resistance than indigo.

9.1 Uses: 1. It can be used as food coloring agent with the provisions of China being able to be used in red and green silk and the maximum usage amount of 0.02g/kg; it can be used in the juice (flavor) beverages, carbonated beverages, wine, candy, pastry coloring, dyeing cherry can decorative) and green plum with the maximum usage amount of 0.10g/kg; the maximal usage amount in the dipping pickles of 0.01g/kg.
2. It is mainly used for the dyeing of cotton yarn, cotton, wool or silk.
3. Reduced indigo is mainly used for dyeing cotton yarn and cotton cloth, being the major dye for blue dye denim. It is also used for wool, silk dyeing and as food coloring and organic pigments.
4. Edible blue pigment;
5. It is mainly used for dyeing cotton yarn, cotton cloth, wool or silk. Pure product can be used for the manufacturing of food dyes, or processed into organic pigments.

9.2 Production method: It is a kind of edible natural blue pigment made from the leaves of Polygonum tinctorium. The indigo leaves are piled up and frequently subject to watering, to ferment 2 to 3 months to become a black clod like. After ramming using mortar, it is known as the ball indigo with the indigo pigment being 2% to 10%. The wood ash, lime and bran are incorporated into ball indigo and further subject to water mixing, heated to 30~40 ℃, exposed to the air to become insoluble blue indigo.
Phenylglycine is taken as raw material and form indole phenol after subjecting to alkali melting, followed by air oxidation to derive the products. There are many ways to synthesize phenylglycine. In our country, the condensation method of aniline and chloroacetic acid is adopted. For the convenience of the refining of phenylglycine, we can first make its insoluble iron salt to remove the impurities before converting into soluble sodium salt and entering into alkali melting process. .
(1) indigo preparation. Edible indigo is actually indigo disulfonic acid disodium. Indigo is subject to sulfonation with concentrated sulfuric acid, followed by dilution with and then soda ash neutralization. Finally add sodium chloride for salting out, filter, wash and dry to get the finished product.
(2) Preparation of indigo aluminum precipitate. First have aluminum chloride and aluminum sulfate have reaction with alkali such as sodium carbonate for preparation of aluminum hydroxide. Then add it to the indigo water solution for precipitation to derive the products.; View all

9.3 Hazards & Safety Information: Category : Toxic substances
Toxic classification : poisoning
Acute toxicity : Oral-mouse LD50> 32000 mg/kg; celiac-mouse LD50: 2200 mg/kg
Flammability and Hazardous properties : being Combustible with combustion producing toxic nitrogen oxide fumes
Storage and transportation characteristics: Ventilated, low temperature and drying
Fire extinguishing agent : dry powder, foam, sand, carbon dioxide, mist water

9.4 Description: Indigo, known chemically as indigotin, is a common blue dye that has been highly valued throughout history and has played a major role in trade and commerce since ancient times. The term indigo is often used to describe many blue dyes produced from a number of plants. For example, woad, a blue dye obtained from the plant Isatis tinctoria, was used throughout the Mediterannean and Europe and is often identified as indigo. True indigo comes from the leguminous plant of the genus Indigofera.
The Indigofera genus includes several hundred species, and indigo has been obtained from a number of these, but the dominant species for the dye are Indigofera tinctoria grown mainly in India and tropical Asia and Indigofera suff ructiosa from the tropical Americas. The name indigo comes from the Greek indikon and Latin indicum meaning “dye from India.” There is evidence that indigo was used several thou sand years b.c.e. Persian rugs containing indigo color exist from several thousand years b.c.e. Textile artifacts from Egyptian tombs provide evidence of indigo’s use by royalty from as far back as 2500 b.c.e. The writings of Herodotus from approximately 450 b.c.e. mention indigo’s use in the Mediterranean area.; View all

9.5 Chemical Properties: dark violet powder

9.6 Occurrence: Indigo is a perennial shrub found in several regions of the world.

9.7 History: Indigotin. The blue dye of the ancient world was derived from indigo and woad. Which plant is the oldest is a matter of conjecture. That indigo was known at least four thousand years ago is evident from ancient Sanskrit writings. Cloth dyed with indigotin (CI Natural Blue; CI 75780) has been found in Egyptian tombs and in the graves of the Incas in South America. Indigo belongs to the legume family. The two most important species are Indigo tinctoria and I. suffruticosa, found in India and the Americas, respectively. The leaves of the indigo plant do not contain the dye as such, but in the form of its precursor, a glycoside known as indican.

9.8 Uses: In recent years researchers have used genetic engineering using Escherichia coli to convert tryptophan into indigo. The desire for natural organic products has also revived traditional production methods of indigo on a small scale. Indigo's dominant use is as a textile dye, but indigo-related compounds have limited use as indicators and in food coloring.the Food and Drug Administration's FD&C Blue #2 contains indigotine (also known as indigo carmine), which is a sulfonated sodium salt of indigo.

9.9 Uses: As textile dye. In sutures.

9.10 Uses: Indigo is a chemical compound used as a dye in industrial clothing and textile processes. Also used in the synthesis of organic semiconductors. Dyes and metabolites.

9.11 Definition: A double indole derivative.

9.12 Definition: indigo: A blue vat dye, C₁₆H₁₀N₂O₂.It occurs as the glucoside indican inthe leaves of plants of the genus Indigofera,from which it was formerlyextracted. It is now made synthetically.

9.13 Production Methods: The first synthesis of indigo is attributed to Adolf von Baeyer (1835–1917), who began hisquest to synthesize indigo in 1865 but was not able to produce indigo until 1878. The syntheticproduction of indigo was first described by Baeyer and Viggo Drewson in 1882; Baeyeralso identified the structure of indigo in 1882.the Baeyer-Drewson synthesis of indigo startedwith 2-nitrobenzaldehyde and acetone proceeding through a series of steps in alkali solution.Baeyer’s work was not commercially viable, and it was not until 1897 that BASF (BadischeAnalin und Soda Fabrik) started to produce indigo commercially using a process developedby Karl von Heumann (1851–1894) that started with naphthalene. The synthetic productionof indigo spelled the end of traditional methods of indigo production. By the second decadeof the 20th century, nearly all indigo was produced synthetically.

9.14 Production Methods: K. Heumann treated N-phenylglycine with alkali and obtained indoxyl (keto form), which on aerial oxidation converted to indigotin. Later, a variation of the original Heumann process was made: aniline, formaldehyde, and hydrogen cyanide react to form phenylglycinonitrile, which is hydrolyzed to phenylglycine. This is the most widely used process for manufacturing indigotin. The greatest improvement in the manufacture of indigotin came when sodamide was used with alkali in the conversion of phenylglycine to indoxyl. Although there is still demand for indigotin for dyeing blue jeans, it has lost a good part of the market to other blue dyes with better dyeing properties.

9.15 General Description: Dark blue powder with coppery luster. Occurs in isomeric forms (cis and trans). In solid state Indigo is in the trans form.

9.16 Air & Water Reactions: Insoluble in water.

9.17 Health Hazard: ACUTE/CHRONIC HAZARDS: Indigo may cause irritation of the skin and mucous membranes.

9.18 Fire Hazard: Flash point data for Indigo are not available but Indigo is probably combustible.

9.19 Safety Profile: Mutation data reported. Whenheated to decomposition it emits toxic vapors of NOx.

9.20 TEST ITEMS: SPECIFICATION

9.21 APPEARANCE: BLUE POWDER

9.22 SHADE: GREENISH

9.23 HEAT RESISTANCE: 180 °C min

9.24 LIGHT FASTNESS: 7

9.25 ACID RESISTANCE: 3

9.26 ALKALI RESISTANCE: 4

9.27 OIL ABSORPTION: 40-50%

9.28 SPECIFIC SURFACE: 27 m ² /g

9.29 DENSITY: 1.60 g/cm ³

9.30 RESIDUE ON 80 MESH: 5.0% max

9.31 WATER SOLUBLE: 1.0% max

9.32 TINTING STRENGTH: 100-105 %

9.33 Purification Methods: First reduce indigo in alkaline solution with sodium hydrosulfite, and filter. The filtrate is then oxidised by air, and the resulting precipitate is filtered off, dried at 65-70o, ground to a fine powder, and extracted with CHCl3 in a Soxhlet extractor. Evaporation of the CHCl3 extract gives the purified dye. [Brode et al. J Am Chem Soc 76 1034 1954; spectral characteristics are listed, Beilstein 24 II 233, 24 III/IV 1791.]

9.34 Storage Conditions: FIRST SYNTHESIS: BAEYER, BER 11: 1296 (1878); 12: 456 (1879). FIRST COMMERCIAL PROCESS: HEUMANN, BER 23: 3043, 3431 (1890).|HARLEY-MASON, J CHEM SOC 1950, 2907; ZIEGLER, KAPPE, MONATSH 96: 889 (1965).|FROM ANILINE & CHLOROACETIC ACID, & FUSING RESULTING PHENYLGLYCINE WITH ALKALI & SODIUM AMIDE. FORMERLY FROM PLANTS OF GENUS INDIGOFERA.|Condensation of aniline, formaldehyde, and hydrocyanic acid to form N-phenylglycinonitrile, followed by alkaline hydrolysis to yield N-phenylglycine which gives indigo in 94% yields. This is the major commercial route used throughout the world

9.35 Experimental Properties: SUBLIMES @ ABOUT 300 °C; DECOMPOSES @ 390 °C; DISSOLVES IN NONPOLAR SOLVENTS WITH RED & IN POLAR SOLVENTS WITH BLUE COLOR; WITH FUMING H2SO4 IT FORMS A SOL SULFONIC ACID; OCCURS AS CIS & TRANS ISOMER; TRANS ISOMER IS SOLID|INDIGO...IS A DYE WHICH IS ESSENTIALLY INSOLUBLE IN WATER IN ITS COLORED OXIDIZED FORM, BUT IS SOLUBLE WHEN REDUCED TO A COLORLESS FORM.

9.36 Reactive Group: Amines, Phosphines, and Pyridines

9.37 FDA Requirements: D & C BLUE NO 6 (INDIGO) MAY BE USED UNDER FEDERAL FOOD, DRUG, & COSMETIC ACT IN COLORING POLY(ETHYLENE TEREPHTHALATE) NONABSORBABLE SUTURES FOR USE IN GENERAL & OPHTHALMIC SURGERY. SPECIFICATIONS FOR CERTIFICATION ARE GIVEN.

9.38 Special Reports: A REVIEW OF THE CHARACTERISTICS OF VARIOUS SYNTHETIC ORGANIC DYES USED AS ADDITIVES IN DRUGS (125 REFERENCES).[HELOU JH; ADDITIVES IN DRUGS. CHARACTERISTICS OF VARIOUS SYNTHETIC ORGANIC DYES; AN FARM QUIM SAO PAULO 18(1) 157 (1979)]

9.39 Fire Hazards: Flash point data for this compound are not available but it is probably combustible. (NTP, 1992)

9.40 Nonfire Spill Response: SMALL SPILLS AND LEAKAGE: If you spill this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then dampen the solid spill material with toluene, then transfer the dampened material to a suitable container. Use absorbent paper dampened with toluene to pick up any remaining material. Your contaminated clothing and absorbent paper should be sealed in a vapor-tight plastic bag for eventual disposal. Solvent-wash all contaminated surfaces with toluene followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned. STORAGE PRECAUTIONS: You should store this material in a refrigerator. (NTP, 1992)

9.41 Personal Protective Equipment: RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with an organic vapor/acid gas cartridge (specific for organic vapors, HCl, acid gas and SO2) with a dust/mist filter. (NTP, 1992)

9.42 Cleanup Methods: INDIGO IS RECOVERED FROM WASTEWATER CONTAINING 0.1 KG/CU M BY FLOCCULATION WITH 0.03 KG/CU M CACL2-MGCL2 & 2.3 KG/CU M NAOH.|WASTEWATER FROM INDIGO DYEING IS FILTERED AT 62 L/MIN ON STAINLESS STEEL SCREEN (128 MESH/CM) & CONCN 100-FOLD BY REVERSE OSMOSIS AT 4.75 M/SEC & 65 DEG/69 BAR THROUGH POROUS STAINLESS STEEL TUBES TO GIVE 4600 L/SQ M/DAY EFFLUENT.

9.43 Natural Pollution Sources: PROBABLY THE OLDEST KNOWN COLORING MATTER. ORIGINALLY OBTAINED FROM VARIOUS SPECIES OF INDIGOFERA, LEGUMINOSAE, INDIGENOUS TO BENGAL, JAVA, GUATEMALA, IN WHICH IT OCCURS AS A GLUCOSIDE.

9.44 Mesh: Chemicals and substances that impart color including soluble dyes and insoluble pigments. They are used in INKS; PAINTS; and as INDICATORS AND REAGENTS. (See all compounds classified as Coloring Agents.)

9.45 Absorption: WAS OBSERVED IN 24-HR URINE SAMPLES COLLECTED AT 14-DAY INTERVALS FROM 6 SHEEP GRAZING PASTURE OF OESTROGENIC CLOVER FROM JULY TO LATE OCTOBER. GENERALLY IT OCCURRED IN ONLY 1 URINE SAMPLE AT EACH COLLECTION BUT FROM MID-AUGUST TO MID-SEPTEMBER IT WAS PRESENT IN 3 OR 4 SAMPLES.

9.46 Metabolism: TWO MOLECULES OF INDOLE WERE OXIDIZED TO FORM ONE MOLECULE OF INDIGOTIN (INDIGO) IN PSEUDOMONAS INDOLOXIDANS, WITH INDOXYL BEING DETECTED AS INTERMEDIATE.

9.47 First Aid: EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. If symptoms such as redness or irritation develop, IMMEDIATELY call a physician and be prepared to transport the victim to a hospital for treatment. INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. If symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop, call a physician and be prepared to transport the victim to a hospital. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing. INGESTION: DO NOT INDUCE VOMITING. If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. Be prepared to transport the victim to a hospital if advised by a physician. If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital. (NTP, 1992); View all

9.48 Human Toxicity Excerpts: ...MAN SPLASHED 7% ALKALINE SOLN OF REDUCED FORM INTO HIS EYES, CONJUNCTIVA APPEARED BLUE SEVERAL HR LATER; CORNEA WAS SOMEWHAT TURBID BUT NOT STAINED. IN COURSE OF 10 DAYS CORNEA GRADUALLY CLEARED & SOME FINE BLUE DOTS WERE SEEN IN STROMA. ...DYE APPEARED TO BE RATHER INERT & NONTOXIC IN TISSUES...

9.49 Mesh Entry Terms: (delta-2,2'-biindole)-3,3'-dione

9.50 Production: < 25,000 lb|(1986) No Data

9.51 Formulations: GRADES: TECHNICAL; PURE

9.52 Manufacturing Info: Textiles, apparel, and leather manufacturing|3H-Indol-3-one, 2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-: ACTIVE|A DOUBLE INDOLE DERIVATIVE

9.53 Use Classification: Cosmetics -> Cosmetic colorant; Masking; Tonic

9.54 Merck: 14,4943

9.55 BRN: 88275

10. Computational chemical data

Molecular Weight: 262.268g/mol
Molecular Formula: C₁₆H₁₀N₂O₂
Compound Is Canonicalized: True
XLogP3-AA: 2.7
Exact Mass: 262.074227566
Monoisotopic Mass: 262.074227566
Complexity: 448
Rotatable Bond Count: 1
Hydrogen Bond Donor Count: 2
Hydrogen Bond Acceptor Count: 3
Topological Polar Surface Area: 65.4
Heavy Atom Count: 20
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Isotope Atom Count: 0
Covalently-Bonded Unit Count: 1
CACTVS Substructure Key Fingerprint: AAADccB7MAAAAAAAAAAAAAAAAAAAAWIAAAAwYAAAAAAAAFgB9AAAHgAQCAAADAyBngAwxvLJkgCoA6RyRASCgCAlYiAImSE1bNgKJvrSlZOEcYhm0BnY2ceayPCOAAAAAAACAAAAAAAAAAQAAAAAAAAAAA==

11. Question & Answer

Can Indigo Revolutionize Psoriasis Treatment? Aug 01 2023
General Description Indigo and its formulations have demonstrated significant efficacy in the treatment of psoriasis. They regulate keratinocyte proliferation, differentiation, and apoptosis by inhibi..
Indigo synthesis from anthranilic acid [closed] Nov 15 2021
Synthesis of indigo: In place of anthranilic acid or aniline, you can simply use 2-nitrobenzaldehyde (see: Baeyer–Drewson indigo synthesis). For the mechanism of the reaction see: WIKIPEDIA. Method:..
Origin of different colour for thio analogue of indigo from blue to red Sep 23 2021
Why the thio analogue of indigo is red? What is the reason behind change of colour from indigo to red just by change of N to S. What I get is that there will be electronegativity, lone pair availabil..
Synthesis of indigo from anthranilic acid - reaction not taking place Jun 25 2021
I was trying to synthesise indigo via the Heumann indigo synthesis (II.), which involves heating antrhanilic acid and chloroacetic acid, both dissolved in isopropanol. After heating up, a hydroxide o..

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