Photographic color development with pyrazoline developers

795,476. Photographic colour development. AGFA AKT.-GES FUR PHOTOFABRIKATION. July 8, 1955 [July 8, 1954], No. 19856/55. Class 98(2) In photographic colour development, 1- (p - aminophenyl) - 3 - aminopyrazoline or a derivative thereof unsubstituted in both amino groups is used as the colour developing substance. The derivative may be one in which one or more hydrogen atoms in the 1 - phenyl nucleus are replaced by halogen atoms or by alkyl or substituted alkyl alkoxy, or sulpho groups. Derivatives specified are 1 - (41 - amino - 31 - methoxyphenyl)-, 1 (41 - amino - 31-methylphenyl)-, 1 - (41 - amino - 21 - methylphenyl)-, 1 - (41 - amino, - 31 - # - hydroxyethylphenyl)-, and 1 - (41 - amino - 3' - # - carboxyethylphenyl) - 3 - aminopyrazoline dihydrochloride. In Example 1, an exposed silver halide emulsion containing 1 - (41 - sulphophenyl) - 3 - palmityl - 5 - pyrazolone is colour developed in 3 minutes to a gamma of 0.7 in a solution containing 1 - (p-aminophenyl) - 3 - aminopyrazolone dihydrochloride, potassium carbonate, potassium bromide and sodium sulphite, as contrasted with a time of 7 minutes to reach the same gamma in a colour developer containing 4 - amino - N - ethyl : N - # - hydroxyethylaniline. A table is given showing the difference in the colours obtained using the two colour developing agents and the following couplers: 41 - stearylaminobenzoylacet - 3 : 5 - dicarboxyanilide, 1 - p - sulphophenyl - 3 - heptadecyl.- 5 - pyrazolone, 1 - naphthol 4 - sulpho - 2 - N - octadecylnaphthamide, 4 - # - octadecylsuccinamylbenzoylacetonitrile, and 1 - p - sulphophenyl - 3 - (41 - stearylaminobenzamido) - 5 - pyrazolone. Similar data are given for the colour developing agents 1-(41-amino - 3' - methoxyphenyl) - 3 - aminopyrazoline and 1 - (41 amino - 2' - methylphenyl) - 3 - aminopyrazoline, both compared with 4 - amino - N - ethyl : N - # - hydroxyethylaniline, and the coupler 1 - p - sulphophenyl - 3 - heptadecyl - 5 - pyrazolone. In examples 2 to 7, the colour developing agent and the coupler are (2) 1 - (41 - amino - 31 - methoxyphenyl) - 3 - aminopyrazoline dihydrochloride and 1 - (41 - sulphophenyl) - 3 - palmityl - 5 - pyrazolone; (3) 1 - (41 - amino - 31 - chlorophenyl) - 3 - aminopyrazoline dihydrochloride and 1 - hydroxy - 4 - sulpho - 2 - naphthoyl - stearylamilide; (4) 1 - (41 - amino - 31 - methylphenyl) - 3 - aminopyrazoline dihydrochloride and 41 - stearylaminobenzoylacet - 3 : 5 - dicarboxyanilide; (5) 1 - (41 - amino - 21 - methylp