Cyan Indoaniline Dyes

35 the design of the ballast side chain is particularly important for reducing the unwanted green and blue absorptions of the cyan chromophore. The selection of the acyl groups is important for adjusting the absorption maximum to the proper wavelength [48], 

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Certain dyes derived from somep-phenylenediamines satisfy the requirements of practical image dyes. For example, the developer of Scheme 5 gives yellow and magenta azamethine dyes, respectively, with benzoylacetanilides and 2-pyrazolin-5-ones as couplers, and cyan indoaniline dyes result from phenols and naphthols. 

Hydroxy-2-Naphthalenecarboxylic Acid. l-Hydroxy-2-naphthoic acid is made similarly to the isomer (2-hydroxy-1-naphthoic acid) by reaction of dry sodium 1-naphthalenolate with CO2 in an autoclave at ca 125°C. It has been used in making triphenylmethane dyes and metalli able a2o dyes. Alkylamides and arylamides of l-hydroxy-2-naphthalenecarboxyhc acid are cyan couplers, ie, components used in indoaniline dye formation in color films (see Color PHOTOGRAPHY). 

Some widely used developers are shown in Fig. 13.41. They can be used to produce the yellow, magenta, and cyan dyes shown in Fig. 13.42. These dye structures demonstrate that acetoacetanilide, pyrazolone, and indoaniline intermediates are useful for producing yellow, magenta, and cyan colors, respectively. 

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