Pyrazolones color photography

Pyrazolines, synthesis from aliphatic diazocompounds 85MI4. 5-Pyrazolone couplers for color photography 87YGK151. 

The pyrazolone dye 16 may serve as an example of the use of pyrazolones as couplers in color photography, which react with the developer (e.g., N,N-diethyl-p-phenylenediamine) in an oxidative coupling process during the chromogenic development. 

Hydrazono-5-(p-dialkylaminophenylimino)seienazoles, pyrazolone azomethin selenazoles, quinoid dyes, and formazans are other important dyes used in photography and the color industry (cf. previous sections). 

Pyrazolone azomethin selenazoles, dyes, photography and color industry,... 

Acid Yellow 23 (Tartrazine) contains the pyrazolone nucleus. It is prepared by coupling diazotized sulfanilic acid with 5-oxo-l-(4-sulfophenyl)-2-pyrazoline-3-carboxylic acid or by heating oxidized tartaric acid (1 mole) with phenylhydrazinesulfonic acid (2 moles). Acid Yellow 23 is useful as a dye for basic fibers, paper, and leather. It also is used as a filter dye in photography. The purified dye is used in food coloring as FD C Yellow 5. 

---