Indigo dye

Recently, bacteria have been genetically engineered to produce indigo dye. 

Indigo is the most important vat dye, dating back to ancient times and produced on an industrial scale since 1880. To replace the indigo dyes, the indanthrone (21) class of dyes was developed. Indanthrone has superior characteristics as a vat dye and became a key material for further development of anthraquinoid vat dyes. There exist a variety of anthraquinone vat dyes differing in the chromophoric system. The color-structure relationship of vat dyes have been rationalized by the Pariser-Parr-Pople molecular orbital (PPP MO) method. Some examples of commercialized anthraquinoid vat dyes are shown in Scheme 6.14... 

The special requirements of the indigo dyeing of cotton warp yarns for denim are capable of being met by indirect electrolysis systems [241]. Examples of four suitable redox systems are shown in Table 12.37. Uniform build-up of depth was observed with each successive step, the results being at least equal to those from the conventional dithionite-based process. Apparendy these processes are amenable to scaling up to bulk production levels [241]. 

Hydroxyacetone In certain applications dithionite can be replaced by hydroxyacetone (e.g. indigo dyeing)... 

Indigo Ring Dyeing Chemistry of Indigo Dyeing. Virkler Company, Charlotte, NC, http //www.virkler.com/expertise/html/chemistry.html... 

Compound 9 when treated with KOH/MeOH gave 2,2 -bis-indole 170, a structural element present in indigo dyes in 89% yield (Scheme 21) <1995T5631>. 

Figure 3.2 Effect of dyebath pH on apparent colour yield in a five-dip indigo dyeing process [29]...

The Chemistry of Indigo Dyeing.—On account of its insolubility the dye itself cannot be applied directly to the fibre. Yet an indirect process of great antiquity is available, for Tyrian purple has been identified as 6 6 -dibromoindigo 1 by Friedlander. The indigo is made soluble... 

A pair of jeans with an overlay of the structure of indigo dye. 

Table 9 Working Conditions and Production Data for a Full-Scale Indigo Dyeing Range...

Examples for such techniques are found in sulfur dyeing for black shades and in a special form in indigo dyeing for denim, where a continuous replenishment of the dyebath is performed for a long period of production. 

Bechtold, T. Burtscher, E. Kiihnel, G. Bobleter, O. Electrochemical processes in indigo dyeing. J. Soc. Dyers Colour. 1997, 113, 135-144. 

Sanroman M, Pazos M, Ricart M, Cameselle C Decolourisation of Textile Indigo Dye by DC Electric Current. Engineering Geology 2005, 77 (3-4),253-61... 

Klessinger M, Liittke W (1963) Theoretical and spectroscopi investigation of indigo dyes II. The chromophore system of the indigo dyes. Tetrahedr Lett 19 (suppl. 2) 315-335. 

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