Patent GB-682665-A (GB)
Title: Improved photographic light-sensitive materials
IPC: G03C7/29
Filed: 1948-02-26
Abstract: Azo dyes for use in photography have the following general structure: [-B(-Ar1-N=N-)a Ar]n which is formed by a plurality of low molecular weight members -B(-Ar1-N=N-)a Ar2 wherein one of Ar1 and Ar2 stands for the residue of a diazo compound, and the other one stands for the residue of an azo coupling component; B stands for a conjugation-interrupting bond connecting two dye units (Ar1-N=N)a Ar2, such as a carbon to carbon linkage, -Ar-O-, -O-, -S-, -SO2-, -CO-, -NH-CO-, alkylene, arylene, -O-alkylene-O-, -O-arylene-O-, N­, -NH-CO-NH-, -Ar-CO-, -SO2NH-, or -NH-X-NH-, -NH-g -NH where X is the divalent radical of a dibasic organic acid and g  is a bivalent hydrocarbon residue; n stands for an integer greater than 1 and a stands for an integer from 1 to 4, the product of a and n being greater than 2.  The dye units (Ar1-N=N)a-Ar may be monazo, disazo, trisazo or polyazo dyes, and the units linked together by conjugation-interrupting bonds are not all identical.  They may contain solubilizing groups such as sulphonic, carboxylic, hydroxyalkyl, polyhydroxyalkyl, hydroxy-amino-alkyl or quarternary amino groups.  In examples: (1) aniline is diazotized and coupled with 1-[4-amino-phenyl]-5 pyrazolone-3-carboxylic acid, the resulting dye is again diazotized coupled with more of the same pyrazolone and these processes are repeated once more, to give a dye which shows only slight diffusion with gelatin.  After two further diazotizations and couplings there is no diffusion. The aniline can be replaced by o-, m- or p-chloroaniline or metanilic acid and the pyrazolone can be replaced, in any or all of the couplings, by 5-(p-amino-benzoyl-amino) phenol-2-sulphonic acid; (2) diazotized acetyl-p-phenylene diamine is coupled with the pyrazolone of example (1) the dye salted out, boiled with potassium hydroxide to split off the acetyl group and treated with phosgene gas, to yield a polymeric dye in which the units <FORM:0682665/IV (c)/1> are linked by C6H4-NH-CO-NH groups.  The same dye is obtained by tetrazotizing diamino-diphenylurea and coupling in pyridine solution with carbonyl-bis-1-(4-amino-phenyl)-5-pyrazolone-3-carboxylic acid; (3) the monoazo dye of example 2 is reacted with succinyl chloride or with ethylene bromide to produce a polymeric azo dye; (4) benzidine-2,21-disulphonic acid 1 or the 3,31-isomer, is tetrazotized and coupled with 1,11[2,21-disulphodiphenylene - (4,41)] - bis - (5 - pyrazolone - 3-carboxylic acid); (5 and 6) benzidine 2,21-disulphonic acid, or the 3,31-isomer is tetrazotized, reacted with H acid, and polymerized with the aid of pyridine; (7) 3,31-diamino-4,41-dimethoxy - diphenylamine chlorohydrate is tetrazotized and coupled with p-amino-benzoyl-H-acid and the resulting dye is tetrazotized and again coupled with p-amino-benzoyl-H-acid twice more; (8) diazotized 4-oxalyamino-aniline-2-sulphonic acid is coupled with 1-amino - naphthalene - 7 - sulphonic acid, the resulting dye is diazotized and coupled with 1 - amino - naphthalene - 6 - sulphonic acid and the product again diazotized and coupled with 2 - amino - 5 - naphthol - 7 - sulphonic acid; the oxalyl group is split off and the dye polymerized by treatment with phosgene. Specification 445,806, [Group XX], is referred to.