Synthetic Indigo

In 1880 Baeyer prepared indigo synthetically from cinnamic acid by various processes [19, 41] —... 

Synthetic carotene. See Cl 40800 Synthetic fluorphlogopite (INCI). See Fluorphlogopite, synthetic Synthetic indigo blue. See Indigo Synthetic iron oxide. See Pigment red 101 Synthetic Japan wax (INCI). See Japan wax, synthetic... 

The THI chromophore is readily synthesized by the interaction of two moles of an o-aminothiophenol (or its salts) with one mole of a 2,3-dihalo-maleic or fitmaric add or their derivatives, as shown in Figure 20-3. The classical indigo synthetic approach is also described. 

Indigoid Base compounds Indigo Synthetic 482-89-3 Widely recognised... 

As early as 2500 bce m India indigo was used to dye cloth a deep blue The early Phoenicians discovered that a purple dye of great value Tyrian purple could be extracted from a Mediterranean sea snail The beauty of the color and its scarcity made purple the color of royalty The availability of dyestuffs underwent an abrupt change m 1856 when William Henry Perkin an 18 year old student accidentally discovered a simple way to prepare a deep purple dye which he called mauveme from extracts of coal tar This led to a search for other synthetic dyes and forged a permanent link between industry and chemical research... 

Piesendy, all ceitified colois aie factory-piepaied materials belonging to one of several different chemical classes. Although a few such as D C Blue No. 6 (indigo) are known to exist in nature, certified colors owe their commercial importance to their synthetic production. Because of the starting materials used in their manufacture in the past, certified colors were once known as coal-tar dyes. Today, since most of the raw materials used in their preparation are obtained from petroleum, this term no longer appHes. 

Humans have used dyes to create color since the dawn of history. Until the mid-nineteenth century, all dyes were of natural origin. Many came from plants, such as indigo, a dark blue dye that was extracted from the leaves of a native East Indian plant. In 1856, the young English chemist William Perkin stumbled upon the first synthetic dye. Perkin was trying to synthesize quinine, a valuable antimalaria dmg. None of his experiments met with success. As he was about to discard the residue from yet another failed reaction, Perkin noticed that it was colored with a purple tinge. He washed the residue with hot alcohol and obtained a purple solution from which strikingly beautiful purple crystals precipitated. Perkin had no idea what the substance was or what reactions had created it, but he immediately saw its potential as a new dye. 

This serendipitous discovery marked the beginning of the synthetic dyestuffs industry, based on coal tar as its main raw material, which is, incidentally, a waste product from another industry, steel manufacture. The development of mauveine was followed by efficient syntheses of natural dyes such as alizarin in 1869 (Graebe and Liebermann, 1869), and indigo in 1878 (Bayer, 1878 Heumann, 1890). The synthetic production of these dyes marked the demise of the agricultural production of these materials and the advent of a science-based, predominantly German chemical industry. The present-day fine chemicals and specialties, e.g. pharmaceuticals, industries developed largely as spin-offs of this coal tar-based dyestuffs industry. 

Yellow to brown compounds are obtained when one or more nitro groups are conjugated with electron-donor substituents such as hydroxy or, of more importance, amino groups. Such dyes are relatively cheap. Picric acid, 2,4,6-trinitrophenol, can be regarded as the oldest synthetic dye it was produced in 1771 by Woulfe by treating indigo with nitric acid. 

CZE using cyclodextrins (CD) as buffer additives has also been employed for the determination of synthetic dyes in various food products. The synthetic dyes New coccine, Erythrosine, Allura red AC, Tartrazine, Sunset yellow FCF, Brilliant blue FCF, Indigo carmine and Fast green FCF were included in the experiments. Measurements were carried out in a used-silica capillary (47 cm length, 40 cm to the detector, 50 pm i.d.). Capillary temperature was 25°C and separation voltage was 20 kV. Pressure injection was performed... 

From these and other similar examples it is clear that the presence of symmetry either in the starting materials or in some of the synthetic intermediates may be very often a complicating factor and the symmetry must be broken in some way in order to proceed along the planned synthetic sequence [10]. This is in contrast with the fact that the presence of symmetry in the target molecule is usually a simplifying factor as we have seen, for example, in the synthesis of indigo discussed in Heading 4.1. 

Uses Manufacturing phthalates, phthaleins, benzoic acid, synthetic indigo, pharmaceuticals, insecticides, chlorinated products, and artificial resins. 

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