Patent GB-938862-A (GB)
Title: Improvements in or relating to photographic diffusion-transfer reversal processes and carboxylated azo dyes used therein
IPC: G03C8/16
Filed: 1960-01-06
Abstract: The invention comprises mono- or dis-azo dyes which have one or two residues of formula <FORM:0938862/IV(a)/1> <FORM:0938862/IV(a)/2> where Y is the non-metallic atoms required to form an aryl, preferably benzene or naphthalene nucleus, Z is the residue of a coupling component, R is an alkyl or substituted alkyl group and the products contain not less than one por o-dihydroxyphenyl group or an alkyl or halogen substituted derivative of such a group.  The dyes may be made by oxidizing corresponding o-hydroxy- or o,o1-dihydroxy-azo dyes to yield quinones which are acylated and reduced to reconstitute the dihydroxyphenyl groups.  The dyes are used in colour photography as developers, in diffusion-transfer processes, where light absorption is temporarily shifted so that they absorb actinic energy during exposure at wave lengths shorter than those absorbed by the dye developer ultimately required and other dyes, which have this characteristic, but do not conform to the above formula, are described, e.g. dyes containing acylated p-hydroxy and o- and p-amino substituted phenol residues such as 1- and 4-(p-(b -(hydroquinoylethyl)-phenylazo) -2-trifluorormethylcarboxamido-naphthalenese and 1-acetoxy-4-(p-(b -(hydroquinonyl)-ethyl)-phenylazo)-naphthalene. Illustrative of starting material dyes are 2(41-(411-(2111,5111 -dihydroxyphenethyl)-phenylazo)-naphthalene azo)-, 2-(p(b -(hydroquinonyl)-ethyl)-phenylazo), 2-(21,5dimethoxy-41-(p-(211, 511-dihydroxyphenyl) -phenylazo)-phenylazo)- and 2-(21,51-dimethoxy-41(p-(211, 511-dihydroxyphenyl)-phenylazo)-4-methoxy-1-naphthols, p-(1-hydroxy-4-methoxy-2naphthaleneazo)-phenethyl catechol, 2-(p-(b hydroquinonyl)-ethyl)-phenylazo)-4-n-propoxy-1-naphthol and 2-(p-(41-methyl-21,51-dihydroxyphenylthioethyl) -phenylazo)- and 2(21,51-dimethoxy-31-(2111,5111 -dihydroxybenzoyl)-ethyl)-phenylazo)-4-methoxy-1naphthols. Indicated for R are methyl, ethyl, propyl, butyl and chloromethyl groups. Oxidation to the quinone is effected with an oxidation agent such as benzoquinone or chloranil.  Acylation is preferably effected with an end ester, especially of formula R3C(R2)C(R1)OCOR where R2 and R3 are H or alkyl and R1 is H, alkyl, alkenyl or aryl, in the presence of an acid catalyst.  The hydroxy groups are regenerated by reduction with e.g. 2,5-xylohydroquinone or hydrogen and a catalyst.  Illustrative of specified esters are 1-propen-2-ol, 4-methyl-1,3-pentadiene-2-ol, 1-phenyl-ethanol, 2-osten-2-ol and vinyl acetates and 1-hexen-2-ol chloroacetate.  Examples are provided of the preparation of the dyes and of their use in photography.  Other specified products include 4-(21-acetoxy-41-[211,511 di-hydroxyphenethyl]-phenylazo)-3-methyl-1phenyl-5-pyrazolone, 1-acetoxy-2-(2(acetoxy-41[411-(2111, 5111-dihydroxyphenethyl)-phenylazo [naphthylazo)-4-methoxy-naphthalene, 3-homogentisamido-4-(o-acetoxyphenylazo)-1-phenyl-5pyrazolone, 1-acetoxy-4-acetyl-2-(41-[211, 511dihydroxyphenethyl]-21-acetoxy-phenylazo)-, 1acetoxy-4-(o-hydroxyphenylazo)-2-(p-[21, 51-dihydroxyphenethyl]-phenylazo- and 1-acetoxy-4(o-acetoxyphenylazo)-2-(o-acetoxy-p-[21, 51-dihydroxy-phenethyl]-phenylazo)-naphthalenes, 1acetoxy-4-(21,51-dihydroxyphenylacetamino) -2(o-acetoxy-p-[21,51-dihydroxyphenethyl]-phenylazo) -benzene and 1-acetoxy-2-(21, 51-diacetoxy41-[211-acetoxy-411 -(2111,5111 -dihydroxyphenethyl) -naphthylazo]-phenylazo-4-methoxy-naphthalene. Dyes containing o- or p-amino or phydroxy groups may be acylated with an appropriate acid chloride or anhydride, the silver halide developing functions being protected.  Specifications 684,591, 684,592, 788,696, 802,175, 811,529, 853,478, 853,479, 853,481, 880,021, 898,706 and 938,867 are referred to.