Indigo dye
| Names | |
|---|---|
| IUPAC name
[2(2′)E]-[2,2′-Biindolylidene]-3,3′(1H,1′H)-dione
| |
| Other names
2,2′-Bis(2,3-dihydro-3-oxoindolyliden)
Indigo Blue Indigotin | |
| Properties | |
| C16H10N2O2 | |
| Molar mass | 262.27 g/mol |
| Appearance | Dark blue solid |
| Density | 1.35 g/cm3 (20 °C) |
| Melting point | 390–392 °C (734–738 °F; 663–665 K) |
| Boiling point | Decomposes |
| 0.000099 g/100 ml (at 25 °C) | |
| Solubility | Soluble in acetic acid, aniline, chloroform, dichloromethane, DMSO, ethyl acetate, nitrobenzene, propylene glycol, conc. sulfuric acid, toluene, xylene Slightly soluble in acetone Insoluble in alcohols, ethers |
| Vapor pressure | ~0 mmHg |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Lethal dose or concentration (LD, LC): | |
| LD50 (Median dose)
|
6400 mg/kg (rat, oral) |
| Related compounds | |
| Related compounds
|
Isatin |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Indigo dye is an organic compound with a distinctive blue color, commonly used in textile coloring.
Contents
Properties
Chemical
Oxidation of indigo dye gives isatin. Nitric acid can be used.
Indigo is a challenging dye because it is not soluble in water. To be dissolved, it must undergo a chemical change, via reduction, usually done with sodium dithionite. This converts indigo into "white indigo" (leuco-indigo). When a submerged fabric is removed from the dyebath, the white indigo quickly combines with oxygen in the air and reverts to the insoluble, intensely colored indigo.
If powdered indigo is added to molten picric acid, the former will decompose with deflagration.[1]
Physical
Indigo is a blue colored solid, almost insoluble in water, but more soluble in organic solvents.
Availability
Pure indigo can be bought online, from various suppliers.
Indigo dye can be extracted from the leaves of some plants of the Indigofera genus, in particular Indigofera tinctoria, in the form of indican, a glycoside. Hydrolysis of indican yields β-D-glucose and indoxyl, the former oxidizes in air to form indigo dye.
Preparation
There are several main synthetic routes to indigo:
- Baeyer-Emmerling indigo synthesis: isatin reacts with phoshporous pentachloride and then reduced with white phosphorus, yielding indigo. Other reducing agents, like zinc powder can be used.
- Baeyer–Drewsen indigo synthesis: the aldol reaction between 2-nitrobenzaldehyde and acetone.[2]
- Pfleger indigo synthesis: N-phenylglycine is treated with a molten mixture of sodium hydroxide, potassium hydroxide and sodium amide. This highly sensitive melt produces indoxyl, which is subsequently oxidized in air to form indigo.
Projects
- Dye clothings
- Make isatin
- Synthesis of indigo carmine
- Compound collecting
Handling
Safety
Indigo dye is safe to handle ,and poses very little toxicity.
Storage
In closed bottles.
Disposal
No special disposal is required. Can be dumped in trash.
References
- ↑ https://www.proquest.com/openview/6e681eea219fbbfc3947b43d2902d48c/1?pq-origsite=gscholar&cbl=41445
- ↑ https://www.youtube.com/watch?v=6yhR242MnwA
