Patent GB-452408-A (GB)
Title: Manufacture of cyanine dyes and of sensitised photographic emulsions
IPC: C09B23/02
Filed: 1934-11-15
Abstract: Cyanine and styryl dyes containing a b b -naphthothiazole nucleus are prepared by subjecting a quaternary ammonium salt of a 2-methyl-b .b <1>-naphthothiazole to condensation with (a) a derivative of a heterocyclic base containing in a -position to the nitrogen a reactive divalent polyatomic grouping (cf. Specification 423,792) or a quaternary ammonium salt of heterocyclic base containing iodine as a substituent in a -position to the nitrogen atom, (b) amylnitrite and acetic anhydride, (c) a quaternary ammonium salt of a heterocyclic base of the quinoline series in alcoholic solution with the aid of an alkaline condensing agent, (d) an orthoformic ester or of another orthocarboxylic acid ester, or diphenylformamidine, or an ester of an arylated thioimidic acid (cf. Specification 412,309), or an acid amide (cf. Specification 439,359) to give in each case symmetrical carbocyanine dyes, (e) a quaternary ammonium salt of another heterocyclic base and diphenylformamidine or an ester of an arylated thioimidic acid, the latter being first condensed with either quaternary salt, to yield finally unsymmetrical carbocyanine dyes, (f) a b -alkoxyacroleinacetal or an a -phenylamino-g -phenyliminopropene hydrohalide to yield pentacarbocyanine dyes, (g) an a  - phenylamino - e  - phenylimino - a  : g  - pentadiene hydrohalide or a dinitrophenyl-pyridinium halide to yield heptacarbocyanine dyes, (h) a dialkylaminobenzaldehyde to yield styryl dyes.  Cyanine and styryl dyes containing a b .b <1> - naphthothiazole nucleus (the term cyanine dye meaning dyes which are characterized by two heterocyclic nuclei containing nitrogen, one of which is tertiary and the other quaternary, the two being linked by a chain of conjugate linkages) are suitable for sensitizing silver halide gelatine emulsions.  They are used in quantities of about 0,5--20,0 milligrams per kilo of uncast emulsion and are incorporated either in the emulsion prior to casting in form of alcoholic solutions, or the finished emulsion is bathed in a solution of the dye.  In examples: (1) 2-methyl-b .b -naphthathiazole diethyl sulphate is condensed with N-ethyl-a -thiotoluquinolone ethiodide in alcoholic piperidine to give a pseudocyanine, with p-toluquinoline ethiodide in alcoholic sodium methanol to give an isocyanine, with p-dimethylaminobenzaldehyde in alcohol containing piperidine to give a styryl dye, with ethylorthoformate, ethylorthoacetate, and ethylorthopropionate in piperidine to give carbocyanine dyes precipitated as the bromides on adding potassium bromide; (2) 2-methyl-b .b <1>-naphthothiazole ethiodide is condensed with methyl- and ethyl-isothioacetanilides in pyridine to give carbocyanine dyes, with 2 - ethylbenzoxazole dimethylsulphate in methanol containing sodium methylate, to give a carbocyanine dye, with b -ethoxyacrolein acetal in pyridine to give a pentacarbocyanine dye, with a -phenylamino-e -phenylimino-a  : g -pentadiene hydrobromide in alcoholic diethylamine to give a heptacarbocyanine dye, with acetic anhydride and amyl nitrite to give a cyanine dye, with 2-acetanilidovinylbenzthiazole ethiodide, 2 - (o  - anilido - methyl) - vinylbenzoxazole ethiodide, 2-(o -anilidoethyl)-vinylbenzthiazole ethiodide and 2-(o -anilidoethyl)-vinyl-5-methoxybenzselenazole ethiodide in presence of pyridine to give carbocyanine dyes. Sensitizing data for these products are furnished.  2-Methyl-b .b -naphthothiazole and its substitution products are made according to Specification 445,538.