482-89-3

Basic information

• Product Name: Indigo
• Synonyms: (2,2’-biindoline)-3,3’-dione;(2,2'-Biindoline)-3,3'-dione;(delta(2,2’(3h,3’h))-biindole)-3,3’-dione;(delta(2,2’)-biindoline)-3,3’-dione;(delta(sup2,2’)-biindoline)-3,3’-dione;(delta2,2'(3H,3'H)-Biindole)-3,3'-dione;(delta2,2'-Biindoline)-3,3'-dione;11669 Blue
• CAS NO: 482-89-3
• Molecular Formula: C₁₆H₁₀N₂O₂
• Molecular Weight: 262.26
• EINECS: 207-586-9
• Product Categories: Organics;chemical reagent;pharmaceutical intermediate;phytochemical;reference standards from Chinese medicinal herbs (TCM).;standardized herbal extract;Inhibitors
• Mol File: 482-89-3.mol
• Article Data: 46

Chemical Properties

• Melting Point: >300 °C(lit.)
• Boiling Point: 405.51°C (rough estimate)
• Flash Point: >220℃
• Appearance: Dark blue to violet/Powder
• Density: 1.01 g/mL at 20 °C
• Vapor Pressure: 1.27E-06mmHg at 25°C
• Refractive Index: 1.5800 (estimate)
• Storage Temp.: Sealed in dry,Room Temperature
• Solubility: DMSO (Slightly, Heated, Sonicated), DMF (Slightly)
• PKA: -3.83±0.20(Predicted)
• Water Solubility: <0.1 g/100 mL
• Stability: Stable. Incompatible with strong oxidizing agents.
• Merck: 14,4943
• BRN: 88275
• CAS DataBase Reference: Indigo(CAS DataBase Reference)
• NIST Chemistry Reference: Indigo(482-89-3)
• EPA Substance Registry System: Indigo(482-89-3)

Safety Data

• Hazard Codes: Xi,Xn
• Statements: 36/38-36/37/38-48/20/21/22
• Safety Statements: 26-36
• RIDADR: UN 3264 8/PG 3
• WGK Germany: 1
• RTECS: DU2988400
• Hazardous Substances Data: 482-89-3(Hazardous Substances Data)

Usage

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.

Uses

Different sources of media describe the Uses of 482-89-3 differently. You can refer to the following data:
1. 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.
2. 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.
3. As textile dye. In sutures.
4. 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.

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.

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

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.

Occurrence

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

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.

Definition

Different sources of media describe the Definition of 482-89-3 differently. You can refer to the following data:
1. A double indole derivative.
2. 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.

Production Methods

Different sources of media describe the Production Methods of 482-89-3 differently. You can refer to the following data:
1. 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.
2. 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.

General Description

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

Air & Water Reactions

Insoluble in water.

Health Hazard

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

Fire Hazard

Flash point data for Indigo are not available but Indigo is probably combustible.

Flammability and Explosibility

Nonflammable

Safety Profile

Mutation data reported. Whenheated to decomposition it emits toxic vapors of NOx.

Properties and Applications

TEST ITEMS SPECIFICATION APPEARANCE BLUE POWDER SHADE GREENISH HEAT RESISTANCE 180 °C min LIGHT FASTNESS 7 ACID RESISTANCE 3 ALKALI RESISTANCE 4 FASTNESS TO BLEEDING 4 OIL ABSORPTION 40-50% SPECIFIC SURFACE 27 m 2 /g DENSITY 1.60 g/cm 3 RESIDUE ON 80 MESH 5.0% max WATER SOLUBLE 1.0% max VOLATITE 105 °C 1.0% max TINTING STRENGTH 100-105 %

TEST ITEMS

SPECIFICATION

APPEARANCE

BLUE POWDER

SHADE

GREENISH

HEAT RESISTANCE

180 °C min

LIGHT FASTNESS

7

ALKALI RESISTANCE

4

FASTNESS TO BLEEDING

4

OIL ABSORPTION

40-50%

SPECIFIC SURFACE

27 m 2 /g

DENSITY

1.60 g/cm 3

RESIDUE ON 80 MESH

5.0% max

WATER SOLUBLE

1.0% max

VOLATITE 105 °C

1.0% max

TINTING STRENGTH

100-105 %

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.]

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

Synthetic route

2-oxoindole (59-48-3) + 2-chloro-3H-indol-3-one (612-54-4) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
In toluene for 1h; Heating;	96%

indole-2,3-dione (91-56-5) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With tetraphosphorus decasulfide In pyridine at 85℃; for 0.0833333h;	90%
Multi-step reaction with 2 steps 1: PCl5 / benzene / 4 h / Heating 2: 70 percent / thiophenol / benzene / 4 h / Heating; further thiophenols used: 1) p-CH3C6H4SH, 2) p-ClC6H4SH, 3) m-CH3C6H4SH, 4) o-CH3C6H4SH View Scheme
Multi-step reaction with 2 steps 1: benzene; phosphorus pentachloride 2: zinc dust; glacial acetic acid View Scheme

1-acetyl-2,3-dihydro-1H-indol-3-one (16800-68-3) + N,O-diacetylindoxyl (16800-67-2) → 1,2-diacetyl-3-indolinone (110912-08-8) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With sulfuric acid In acetic anhydride at 20℃; for 20h;	A 88.8% B n/a

1-acetyl-2-propionyl-3-indolinone (110912-09-9) → 1-(3-Hydroxy-1H-indol-2-yl)-propan-1-one (110912-10-2) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With sodium hydroxide at 20℃; for 2h;	A 86.4% B n/a

1,2-diacetyl-3-indolinone (110912-08-8) → 1-(3-Hydroxy-1H-indol-2-yl)ethanon (22079-15-8) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With sodium hydroxide at 20℃; for 2h;	A 85.7% B n/a

N,O-diacetylindoxyl (16800-67-2) + propionic acid anhydride (123-62-6) → 1-acetyl-2-propionyl-3-indolinone (110912-09-9) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With sulfuric acid In acetic anhydride	A 72% B n/a

2-chloro-3H-indol-3-one (612-54-4) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With thiophenol In benzene for 4h; Heating; further thiophenols used: 1) p-CH3C6H4SH, 2) p-ClC6H4SH, 3) m-CH3C6H4SH, 4) o-CH3C6H4SH;	70%
With hydrogen iodide; acetic acid
With acetic acid; zinc
With ammonium sulfide
With phosphorous

1-acetyl-2-benzoyl-3-indolinone (110912-11-3) → 2-benzoyl-3-hydroxyindole (22078-82-6) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With sodium hydroxide In methanol at 20℃; for 20h;	A 67.8% B n/a

1-(phenylsulfonyl)-2-trimethylsilylindol-3-yl trifluoromethanesulfonate (144646-98-0) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With tetrabutyl ammonium fluoride In tetrahydrofuran	51%

2,3-dioxo-2,3-dihydro-1H-indole-5-sulfonate (78551-19-6) + 1H-indol-3-ol anion → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) + indirubin-5'-sulfonate

Conditions	Yield
With N,N'-bis(6A-deoxy-β-cyclodextrin-6A-yl)NHCOCONH In water at 20℃; pH=10.0; Product distribution; Further Variations:; Reagents;	A 1.8% B 36%

3-methylbenzo[c]isoxazole (4127-53-1) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
at 300℃; for 2h; spray vacuum pyrolysis;	15%

oxirane (75-21-8) + aniline (62-53-3) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With potassium hydroxide; sodium hydroxide; sodium amide at 200℃; Reaktion ueber mehrere Stufen;

pyridine (110-86-1) + indolin-3-one (3260-61-5) + 2-chloro-3H-indol-3-one (612-54-4) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

indole (120-72-9) + Perbenzoic acid (93-59-4) + chloroform (67-66-3) → N-formyl-2-aminobenzaldehyde (25559-38-0) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

indole (120-72-9) + Perbenzoic acid (93-59-4) → N-formyl-2-aminobenzaldehyde (25559-38-0) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With chloroform

indole (120-72-9) → indoxyl (480-93-3) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

indole (120-72-9) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With air; sodium sulfite
With air; sodium hydrogensulfite
With dihydrogen peroxide; sodium hydrogencarbonate

2-acetylnitrobenzene (577-59-3) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With soda lime; methyllithium; calcium carbonate; zinc
Multi-step reaction with 5 steps 1: H2 / Pd-C 2: aq NaNO2, 1:1 dil aq HCl / 0 °C 3: aq NaN3/NaOAc / 0.17 h 4: xylene / Heating 5: 15 percent / 2 h / 300 °C / spray vacuum pyrolysis View Scheme
Multi-step reaction with 4 steps 1: H2 / Pd-C 2: aq NaNO2, 1:1 dil aq HCl / 0 °C 3: aq NaN3/NaOAc / 0.17 h 4: 0.5 g / 2 h / 300 °C / spray vacuum pyrolysis View Scheme

2-chloro-3H-indol-3-one (612-54-4) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) + indirubin (479-41-4)

Conditions	Yield
With acetic acid; zinc

2-formyl-3-hydroxyindole (172984-51-9) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
Oxydieren;

1H-indole-3-carboxylic acid (771-50-6) → anthranilic acid (118-92-3) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With sodium hydroxide; ozone; acetone

3-hydroxy-1H-indole-2-carboxylic acid (6245-93-8) + 3-(2-nitrophenyl)-2-propynoic acid (530-85-8) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With sodium carbonate

3-hydroxy-1H-indole-2-carboxylic acid (6245-93-8) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

1-hydroxy-1H-indole-2-carboxylic acid (16264-71-4) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With sulfuric acid

2'-nitro-chalcone (16619-38-8) → benzaldehyde (100-52-7) + benzoic acid (65-85-0) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
Sonnenlicht;

2-phenylimino-indolin-3-one (6411-55-8) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With hydrogen sulfide

D-glucose (50-99-7) + 2-Nitrobenzoylessigsaeure (22751-16-2) + furan-2,3,5(4H)-trione pyridine (1:1) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

β-(2-Nitrophenyl)-β-propiolacton (78992-73-1) + acetic acid (64-19-7) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

1-nitro-2-(2-nitrovinyl)benzene (5670-66-6, 5670-67-7, 3156-39-6) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With sodium dithionite

3-(2-nitrophenyl)-2-propynoic acid (530-85-8) → 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3)

Conditions	Yield
With hydrogen sulfide; sodium carbonate
With potassium xanthate; water; potassium carbonate
With D-glucose

iodobenzene (591-50-4) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → N,N'-diphenyl-indigo

Conditions	Yield
With copper; potassium carbonate In 1,2-dichloro-benzene for 10h; Heating;	91.7%

1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → indole-2,3-dione (91-56-5)

Conditions	Yield
With potassium dichromate; sulfuric acid In water at 40 - 45℃; for 1.5h;	90%
With sodium hydroxide Erwaermen des Reaktionsprodukts mit Salpetersaeure (15%ig) die Chromsaeure enthaelt, nach Filtern und den Rueckstand in Natronlauge Loesen und Behandeln mit Saeure;
With nitric acid
With chromic acid
With oxygen; methylene blue In dimethylsulfoxide-d6 for 8h; Irradiation;

di-tert-butyl dicarbonate (24424-99-5) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 1,1'-bis(tert-butoxycarbonyl)-bis(2,2'-indolidene)-3,3'-dion

Conditions	Yield
With dmap In dichloromethane at 20℃; for 48h; Inert atmosphere;	90%
With dmap In dichloromethane at 20℃;	89%
With dmap In N,N-dimethyl-formamide at 20℃; for 20h;	85.2%

acetic acid (64-19-7) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 2,2'-diacetoxy-1,2,1',2'-tetrahydro-[2,2']biindolyl-3,3'-dione (908835-88-1)

Conditions	Yield
With potassium permanganate at 20℃;	88%
With lead dioxide
With manganese(IV) oxide

acetic anhydride (108-24-7) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 1H,1'H-2,2'-­bisindol-­3-­yl acetate (69423-26-3)

Conditions	Yield
With tin; acetic acid at 64 - 66℃; reductive acetylation;	88%
With tin In acetic acid at 64 - 66℃;	85%
With tin; acetic acid at 64 - 66℃; for 3h;	85%
With iron; acetic acid at 64 - 66℃; for 2.5h;	82%

acetic anhydride (108-24-7) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 2,2'-biindole (40899-99-8) + 1H,1'H-2,2'-­bisindol-­3-­yl acetate (69423-26-3)

Conditions	Yield
With tin In acetic acid at 64 - 66℃; for 2.5h;	A 1% B 88%

acetic anhydride (108-24-7) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 2,2'-biindole (40899-99-8) + 1-acetyl-2,3-dihydro-2,2'-bisindole (172950-81-1) + 1H,1'H-2,2'-­bisindol-­3-­yl acetate (69423-26-3)

Conditions	Yield
With acetic acid; zinc at 60 - 62℃; for 8h;	A 3% B 82% C 3%
With zinc In acetic acid at 60 - 62℃; for 8h;	A 3% B 82% C 3%
With zinc In acetic acid at 49 - 52℃; for 8h; Product distribution; var. metal, temp., time, atm.;	A 46% B 21% C 18%

4-iodo-benzoic acid hexyl ester (501102-39-2) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → N,N'-di(p-hexanoxycarbonylphenyl)indigo

Conditions	Yield
With copper; potassium carbonate In 1,2-dichloro-benzene for 17h; Heating;	80.7%

1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → dibenzo{b,g}{1,5}-naphthiridin-6,12(5,11H)-dione (17352-37-3)

Conditions	Yield
In gas at 460℃;	80%

2-propynyl chloride (624-65-7) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 1-(prop-2-yn-1-yl)-[2,2'-biindolinylidene]-3,3'-dione + 6-methylene-6,7-dihydropyrazino[1,2-a:4,3-a']diindole-13,14-dione (1447733-33-6)

Conditions	Yield
Stage #1: 1H,1H'-2,2'-Biindolylidene-3,3'-dione With caesium carbonate In N,N-dimethyl-formamide at 88℃; for 1h; Inert atmosphere; Molecular sieve; Stage #2: 2-propynyl chloride In N,N-dimethyl-formamide for 0.0833333h; Inert atmosphere; Molecular sieve; Cooling with ice;	A 3% B 79%

para-iodoanisole (696-62-8) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → N,N'-bis-4-methoxyphenylindigo

Conditions	Yield
With copper; potassium carbonate In 1,2-dichloro-benzene for 10h; Heating;	73.8%

allyl bromide (106-95-6) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 8H,16H-pyrido[1,2,3-s,t]-indolo[1,2-a]azepino[3,4-b]indol-17-one (1201851-45-7) + 1-allyl-10'-allyloxy-2'H-spiro(indoline-2,1'-pyrido[1,2-a]indol)-3-one (1201851-44-6)

Conditions	Yield
Stage #1: 1H,1H'-2,2'-Biindolylidene-3,3'-dione In N,N-dimethyl-formamide at 20℃; for 0.5h; Inert atmosphere; Sonication; Stage #2: With caesium carbonate In N,N-dimethyl-formamide at 85 - 88℃; for 0.5h; Inert atmosphere; Molecular sieve; Stage #3: allyl bromide In N,N-dimethyl-formamide at 85 - 88℃; for 3h; Inert atmosphere; Molecular sieve;	A 72% B 15%

acetyl chloride (75-36-5) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → N-acetylindigo (102396-60-1)

Conditions	Yield
In pyridine at 45℃; for 2h;	70%
With sodium hydride 1.) HMPA, 0 deg C, 4 h, 2.) HMPA, 15 h; Yield given. Multistep reaction;

2-methyl-3-bromo-1-propene (1458-98-6) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 7,15-dimethyl-8H,16H-pyrido[1,2,3-s,t]-indolo[1,2-a]azepino[3,4-b]indol-17-one (1201851-47-9) + 3'-methyl-1-[3-(2-methyl)prop-1-enyl]-10'-[3-(2-methyl)-prop-1-enyl]oxy-2'H-spiro(indoline-2,1'-pyrido[1,2-a]indol)-3-one (1201851-46-8)

Conditions	Yield
Stage #1: 1H,1H'-2,2'-Biindolylidene-3,3'-dione In N,N-dimethyl-formamide at 20℃; for 0.5h; Inert atmosphere; Sonication; Stage #2: With caesium carbonate In N,N-dimethyl-formamide at 85 - 88℃; for 0.5h; Inert atmosphere; Molecular sieve; Stage #3: 2-methyl-3-bromo-1-propene In N,N-dimethyl-formamide at 85 - 88℃; for 3h; Inert atmosphere; Molecular sieve;	A 69% B 15%

pyridine-3-carbonyl chloride hydrochloride (20260-53-1) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → N,N'-dinicotinoyl-2,2'-bi-indolinylidene-3,3'-dione (95201-47-1)

Conditions	Yield
With pyridine at 50℃; for 5h;	68%

μ-diiodo-di((η5-pentamethylcyclopentadienyl)(iodo)iridium) + phthalocyaninatotin(II) (15304-57-1) + tetrabutylammomium bromide (1643-19-2) + 1,2-dichloro-benzene (95-50-1) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 2C16H36N(1+)*0.5C16H12N2O2*2.5C6H4Cl2*2C58H39IrN10O2Sn(1-)

Conditions	Yield
Stage #1: phthalocyaninatotin(II); tetrabutylammomium bromide; 1,2-dichloro-benzene; 1H,1H'-2,2'-Biindolylidene-3,3'-dione With fluorenone radical anion sodium contact ion pair at 80℃; for 24h; Stage #2: μ-diiodo-di((η5-pentamethylcyclopentadienyl)(iodo)iridium) at 80℃; for 24h;	67%

1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → d2-indigo (78347-23-6)

Conditions	Yield
With pyridine; d(4)-methanol for 12h; 1.)reflux, 2 h 2.)20 deg C, 12 h;	66.2%

(E)-1-Bromo-2-butene (4784-77-4, 39616-19-8, 29576-14-5) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 2'-methyl-1-[1-(but-2-enyl)]-10'-[1-(but-2-enyl)]oxy-2'H-spiro(indoline-2,1'-pyrido[1,2-a]indol)-3-one

Conditions	Yield
Stage #1: 1H,1H'-2,2'-Biindolylidene-3,3'-dione In N,N-dimethyl-formamide at 20℃; for 0.5h; Inert atmosphere; Sonication; Stage #2: With caesium carbonate In N,N-dimethyl-formamide at 85 - 88℃; for 0.5h; Inert atmosphere; Molecular sieve; Stage #3: (E)-1-Bromo-2-butene In N,N-dimethyl-formamide at 85 - 88℃; for 3h; Inert atmosphere; Molecular sieve;	65%

1-Bromo-2-butyne (3355-28-0) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 13-(but-2-yn-1-yl)-7a-methylbenzo[b]indolo[1,2-h][1,7]naphthyridine-8,14-(7aH,13H)-dione

Conditions	Yield
Stage #1: 1H,1H'-2,2'-Biindolylidene-3,3'-dione With caesium carbonate In N,N-dimethyl-formamide at 85℃; for 0.5h; Inert atmosphere; Stage #2: 1-Bromo-2-butyne In N,N-dimethyl-formamide at 85℃; for 0.0666667h; Inert atmosphere;	65%

1,2-dichloro-benzene (95-50-1) + [2.2.2]cryptande (23978-09-8) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 6C18H36N2O6*6C16H10N2O2(1-)*6K(1+)*C16H10N2O2*5.5C6H4Cl2

Conditions	Yield
With potassium graphite at 80℃; Inert atmosphere; Glovebox;	63%

2-methyl-3-bromo-1-propene (1458-98-6) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → 8a-hydroxy-7-methyl-13-(2-methylallyl)-8,13a-dihydroazepino[1,2-a:3,4-b']diindol-14(8H)-one + (E)-1-(2-methylallyl)-[2,2'-biindolinylidene]-3,3'-dione

Conditions	Yield
Stage #1: 1H,1H'-2,2'-Biindolylidene-3,3'-dione In N,N-dimethyl-formamide for 0.5h; Inert atmosphere; Sonication; Stage #2: With caesium carbonate In N,N-dimethyl-formamide at 85 - 88℃; for 0.5h; Inert atmosphere; Stage #3: 2-methyl-3-bromo-1-propene In N,N-dimethyl-formamide for 0.00138889h; Time; Inert atmosphere;	A 7% B 62%

1-Iodonaphthalene (90-14-2) + 1H,1H'-2,2'-Biindolylidene-3,3'-dione (482-89-3) → N-naphthylindigo

Conditions	Yield
With copper; potassium carbonate In 1,2-dichloro-benzene for 13h; Heating;	60%

Upstream product

• 120-72-9 indole 
• 480-93-3 indoxyl 
• 16433-96-8 2-ethynyl-1-nitrobenzene 
• 75-21-8 oxirane 
• 62-53-3 aniline 
• 93-59-4 Perbenzoic acid 
• 67-66-3 chloroform 
• 172984-51-9 2-formyl-3-hydroxyindole 
• 771-50-6 1H-indole-3-carboxylic acid 
• 16264-71-4 1-hydroxy-1H-indole-2-carboxylic acid 
• 6411-55-8 2-phenylimino-indolin-3-one 
• 78992-73-1 β-(2-Nitrophenyl)-β-propiolacton 
• 64-19-7 acetic acid 
• 109407-88-7 2,3-epoxy-3-(2-nitro-phenyl)-propionic acid 

Downstream Products

• 6537-68-4 leucoindigo 
• 1603-79-8 phenylglyoxylic acid ethyl ester 
• 91-55-4 2,3-dimethylindole 
• 6417-52-3 5,14b-diaza-benzo[b]benzo[5,6]cyclohepta[1,2,3-lm]fluorene-10,15-dione 
• 72738-57-9 trans-N,N'-dibenzoylindigo 
• 77251-14-0 1,1'-bis-(4-nitro-benzoyl)-1H,1'H-[2,2']biindolylidene-3,3'-dione 
• 6417-51-2 7,14-diphenyl-diindolo[3,2,1-de;3',2',1'-ij][1,5]naphthyridine-6,13-dione 
• 120-72-9 indole 
• 15206-55-0 methyl 2-oxo-2-phenylacetate 
• 172984-51-9 2-formyl-3-hydroxyindole 
• 118-92-3 anthranilic acid 
• 118-48-9 isatoic anhydride 
• 6374-92-1 5,7-dichloroisatin 
• 17630-76-1 5-chloroindole 2,3-dione 

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