Patent GB-571025-A (GB)
Title: New azamethine dyestuffs useful as photographic densitisers
IPC: C09B23/16
Filed: 1943-10-16
Abstract: Compounds regardable as anils are prepared by condensing a 1-alkyl- or 1-aryl-2-aryl-3-nitrosoindole, which may carry simple substituents such as halogen, nitro, alkyl, or alkoxy, with 2 - methylthiazole, 2 - methylselenazole, 2 : 3 : 3-trimethylindolenine or with pyridine substituted by methyl in at least one of the 2-or 4-positions or with a corresponding benz-substituted compound or with a corresponding quaternary ammonium compound.  The nitroso compound may be 1-ethyl-2-phenyl-3-nitrosoindole, 1 - ethyl - 2 - p - chlorophenyl - 3 - nitroso - indole, 1 : 2-diphenyl-3-nitrosoindole, or 1-ethyl-2 - phenyl - 3 - nitroso - 5 - ethoxyindole.  The heterocyclic nitrogen compound may be a -picoline methiodide, lepidine methiodide, 2 : 3 : 3-trimethylindolenine methiodide, or the methyl chloride quaternary salts of g -picoline quinaldine, 2-methylbenzthiazole, 2-methylbenzselenazole, or 2 - methyl - 4 : 5 : 6 : 7 - tetra-hydrobenzthiazole.  The condensation may be effected in the absence of a catalyst or in the presence of a catalyst such as piperidine, pyridine, or sodium hydroxide.  The compounds may be used as desensitizers for silver halide emulsions before or after coating and before or after exposure.  In examples: (1) 1-ethyl-2-phenyl - 3 - nitrosoindole and a  - picoline methiodide are condensed in presence of pyridine or sodium hydroxide solution; (2) 1-ethyl-2-phenyl-3-nitrosoindole and lepidine methiodide are condensed in presence of piperidine; (3) 1 - ethyl - 2 - phenyl - 3 - nitrosoindole and 2 : 3 : 3-trimethylindolenine hydriodide are condensed; (4) 1 - ethyl - 2 - phenyl - 3 - nitrosoindole and quinaldine methiodide are condensed in presence of piperidine; (5) 1-ethyl-2-phenyl-3-nitrosoindole and quinaldine ethiodide are condensed in presence of piperidine; (6) 1-ethyl-2-phenyl-3-nitrosoindole and lepidine ethiodide are condensed in presence of piperidine; (7) 1-ethyl-2-phenyl-3-nitrosoindole and g -picoline methiodide are condensed in presence of sodium hydroxide; (8) 1 - ethyl - 2 - phenyl - 3 - nitrosoindole and 2-methylbenzthiazole ethiodide are condensed; (9) 1 - ethyl - 2 - phenyl - 3 - nitrosoindole and 2 - methyltetrahydrobenzthiazole methiodide are condensed in presence of piperidine; (9) 1-ethyl-2-phenyl-3-nitrosoindole and nitro-2 : 3 : 3-trimethylindolenine methobromide are condensed; (11) 1 : 2-diphenyl-3-nitrosoindole and lepidine methiodide are condensed in presence of piperidine; (12) 1 : 2-diphenyl-3-nitrosoindole and a -picoline methiodide are condensed in presence of sodium hydroxide and aqueous hydriodic acid added; (13) 1 : 2-diphenyl-3-nitrosoindole and g -picoline methiodide are condensed in presence of sodium hydroxide and aqueous hydriodic acid added; (14) 1 : 2-diphenyl-3-nitrosoindole and 2-methylbenzthiazole ethiodide are condensed; (15) 1 : 2-diphenyl-3-nitrosoindole and 2 : 3 : 3 - trimethylindolenine methiodide are condensed; (16) 2 - p - chlorphenyl - 1 - ethyl - 3 - nitrosoindole and lepidine methiodide are condensed in presence of piperidine; (17) 2-p-chlorphenyl-1-ethyl-3-nitrosoindole and a -picoline methiodide are condensed in presence of sodium hydroxide; (18) 2 - p - chlorphenyl - 1 - ethyl - 3 - nitrosoindole and g -picoline methiodide are condensed in presence of sodium hydroxide and aqueous hydriodic acid is added; (19) 2-p-chlorphenyl-1 - ethyl - 3 - nitrosoindole and 2 - methylbenz - thiazole ethiodide are condensed together; and (20) 2 - phenyl - 1 - ethyl - 5 - ethoxy - 3 - nitrosoindole and lepidine methiodide are condensed in presence of piperidine. Comparative data are given for the desensitizing action of the anils and of Pinacryptol Yellow when used for bathing emulsions.