Indigo

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indigo

[Span.; from Lat.,=Indian], important blue dyestuff used in printing inks and for vat dyeing of cotton (see dyedye,
any substance, natural or synthetic, used to color various materials, especially textiles, leather, and food. Natural dyes are so called because they are obtained from plants (e.g., alizarin, catechu, indigo, and logwood), from animals (e.g.
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). It was anciently produced in India and was known in Egypt, probably c.1600 B.C.; mummies of the XVIII dynasty have been discovered wrapped in indigo-dyed cloth. Indigo is obtained from leguminous plants of the genus Indigofera, chiefly from the Asian species Indigofera tinctoria, but also from several other species. The plants contain a colorless, soluble glucoside called indican. When the macerated plants are allowed to ferment in vats of water the colorless form of indigo is liberated; stirring of the liquid causes oxidation of the colorless material to form a blue sediment. The natural indigo gives a strong blue color of great permanence. Use of the natural dye greatly decreased after the synthesis of indigo was accomplished. Adolf von Baeyer was the first to synthesize it, but others developed the methods used for its commercial production from anilineaniline
, C6H5NH2, colorless, oily, basic liquid organic compound; chemically, a primary aromatic amine whose molecule is formed by replacing one hydrogen atom of a benzene molecule with an amino group.
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 and chloroacetic acid.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Indigo

 

plants containing the glycoside indican, the source of blue indigo dye. Only a few indigo plants contain a sufficient quantity of indican for practical use. The most important indigo plant is Indigofera tinctoria, which is native to southern Asia and was once widely cultivated. After the synthesis of indigo, the significance of this and other indigo plants decreased sharply. In the USSR the species Isatis tinctoria and Polygonum tinctoria are occasionally cultivated


Indigo

 

a dark blue crystalline substance; its structural formula is Its melting point is 390°-392°C (with decomposition). It is insoluble in water and alcohol and slightly soluble in other organic solvents.

Indigo, which has been known since remote antiquity, is a dye obtained from indigo plants (for example, Indigofera tinctoria); it is extensively used for vat dyeing cotton and silk blue. The principal method of obtaining indigo is by reacting aniline with chloroacetic acid to give phenylglycine, which is then fused with alkali to give indoxyl, which in turn is oxidized to indigo by the oxygen in the air. Reduction of indigo gives the leuco compound indigo white, whose sodium salt of sulfuric acid ester is called indigosol. Owing to the inadequate durability of indigo, it has been replaced by other vat dyes. The determination of the structure of indigo and development of methods of synthesizing it at the end of the 19th century was the start of the development of the manufacture of indigoid dyes.

IU. E. GERASIMENKO

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

indigo

[′in·də·gō]
(organic chemistry)
A blue dye extracted from species of the Indigofera bush.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

indigo

1. any of various tropical plants of the leguminous genus Indigofera, such as the anil, that yield this dye
2. 
a. any of a group of colours that have the same blue-violet hue; a spectral colour
b. (as adjective): an indigo carpet
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

Indigo

(1) An earlier family of desktop graphics computers from SGI. The low end were the Indy machines, which included their own digital video camera. The high end included a variety of Indigo workstations, with models specialized for graphics functions such as accelerated texture mapping and image processing. See SGI.

(2) The code name of the messaging system introduced in Windows Vista. See Windows Communication Foundation.
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References in periodicals archive ?
One essential item for your wardrobe this summer has to be a pair of cropped jeans in a dark indigo shade.
Soft Touch features a lighter-weight denim (10 ounces) in two shades, light blue and dark indigo, and is intended for use in bedding, pillows, curtains and any other fabrications that call for a finer hand.
Go for a saturated wash, dark indigo or steel grey, and a flattering fit - skinny, slim or boot cut.
Frill jersey dress with sequins, pounds 35; Yellow prep jumper with three-quarter sleeves, pounds 30; dark Indigo bootcut jeans, pounds 35; leather look tan bag,pounds 30; gold and amber long chain necklace,pounds 8; Indigo frill sleeve dress, pounds 40; selection of gold bangles,pounds 8/pounds 12; Pink bow dress, pounds 45; black and gold ring,pounds 6; Leopard chiffon blouse,pounds 30; black pencil skirt,pounds 30; black suede belt with gold,pounds 18; print bangles,pounds 8 for three; Purple floral dress with tie at back,pounds 38, purple bangle,pounds 12; Red tartan check blouse,pounds 35; indigo front pencil skirt,pounds 30; Grey leopard print dress,pounds 45; Grey jersey cami with sequins,pounds 22; grey jersey long-sleeved hoody, TBC
Girl wears dark indigo denim cropped jeans pounds 18-20, blue/navy stripy T-shirt pounds 12-14 from Boden (0208-453 1535); black on white stripe top pounds 12.99, cords pounds 16.99 from Tesco; rugby top pounds 14.99, jeans pounds 39.99 both from River Island; polo top pounds 14, crew neck T-shirt pounds 5, crew neck long sleeve T-shirt pounds 12, zip-through hooded track jacket pounds 22, ria jeans pounds 35, square shoulder bag pounds 12 from Top Shop
The suiting and separates are in quality fabrics from the white cotton rich shirt (with elastane for comfort, fit and shape retention) to the dark indigo jeans (with stretch Lycra to fit the natural body shape) and joy, a plain, logo-less ribbed polo neck jumper.
Black wool traditional duffle EUR122, Dark indigo silm jeans EUR54
Grey, black and dark indigo denim are the most popular colours this season.
The highwaist jean is really on trend in deep dark indigo, perfect worn with a ditsy print blouse or bow detail cashmere knits.
DARK Indigo Denim Jacket pounds 91 by Swish Jeans (0171 494 1240).
THE dark indigo denim Earl jean explosion happened three years ago and the super-lean styling remains hard to beat.
Victoria Beckham and Jennifer Lopez favour fitted dark indigo stretch jeans from hip US designer Frankie B and Geri Halliwell goes for the bleached Gap versions at a much more reasonable pounds 38.