Colour Couplers and Derived Dyes

Yellow Couplers and Dyes. All the useful yellow couplers are based on acetanilides, especially the pivaloyl and benzoyl derivatives (2.83), which react to give the azomethine dyes (2.84) absorbing at wavelengths in the region 450 80 nm. 

Cyan Couplers and Dyes. Cyan couplers need to produce very bright dyes absorbing in the region of 630-700 nm and to date only phenols and, to a much lesser degree, naphthols have been found to be commercially acceptable. Typical is the phenol (2.89) used in both eolour reversal and colour negative films, depending on the nature of the R group, to produee indophenols, e.g. (2.90). 

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