Indigo

Reported in EPA TSCA Inventory.

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: 40.62Ų ; (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: