Indigo(redirected from Dark Indigo)
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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
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 Owing to the inadequate durability of indigo, it has been replaced by other vat dyes.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
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.