Patent GB-552309-A (GB)
Title: Improvements in and relating to polymethine dyes and to photographic emulsions containing such dyes
IPC: C09B23/06
Filed: 1941-08-16
Abstract: 552,309. Cyanine dyes. KODAK, Ltd. Aug. 16, 1941, No. 1463/43. Convention date, Aug. 21, 1940. Divided out of 551,824. Drawings to Specification. [Class 2 (iii)] [Also in Group XX] Dyes are made by condensing a 2-methyl-3- arylbenzthiazolium salt with an ester of orthoformic acid. 3 : 3<SP>1</SP> - diphenylthiacarbocyanine iodide is prepared by refluxing together 2 - methyl - 3 - phenylbenzthiazolium iodide and ethyl orthoformate in anhydrous pyridine. Dyes are made by condensing a 3 - arylbenzthiazolium salt having an w - arylacylaminovinyl group in the 2 - position either with a cyclammonium alkyl or aryl quaternary salt having a reactive methyl group in the α- or γ- position to the quaternary nitrogen atom or with a compound having a methylene group adjacent to a carbonyl group, e.g. a rhodanine, thionaphthenone, thiobarbituric acid, or 2 - thio - 2 : 4 - oxazoledione. 3 - ethyl - 5 - [(3 - phenyl - 2 - benzthiazolylidene) -. ethylidene]- rhodanine is prepared by refluxing together 2 - (w - - acetanilidovinyl) - 3 - phenylbenzthiazolium iodide, 3 - ethylrhodanine, and triethylamine in ethyl alcohol. Triethylamine may be replaced by piperidine, diethylamine, N - methylpiperidine, or pyridine. A styryl dye is made by condensing a 3 - arylbenzthiazole quaternary salt having a methyl group in the 2 - position with a dialkylaminobenzaldehyde. 2 - (p - dimethylaminostyryl)-3-phenylbenzthiazolium perchlorate is prepared by refluxing 2 - methyl - 3 - phenylbenzthiazolium iodide, p - dimethylaminobenzaldehyde, and piperidine in ethyl alcohol, and adding sodium perchlorate. Polymethine dyes formed from a 2 - methyl - 3 - arylbenzthiazolium salt (other than by condensation with ortho - α - thiophenic acid) in which the aryl group is devoid of nitro groups may be used as sensitizers for gelatino-silver halide emulsions, and may be incorporated in' the finished washed emulsion or by bathing after coating. Sensitizing data are given in respect of the dyes 3 : 3<SP>1</SP> - diphenylthiacarbocyanine iodide, 3 - ethyl - 5 - [(3 - phenyl - 2 - benzthiazolylidene) - ethylidene] - rhodanine, and 2 - (p - dimethylaminostyryl) - 3 - phenylbenzthiazolium perchlorate when incorporated in gelatino-silver bromiodide emulsions. The dyes may also be incorporated in silver bromide and chloride emulsions. 2 - (p - dimethylaminostyryl) - 3 - phenylbenzthiazolium perchlorate may also be used as a filter or antihalation dye, being decolorized in a developer. Samples have been furnished under Sect. 2 (5) of the Acts of (1) 3 - ethyl - 5 [(3-phenyl-2- benzthiazolidene) - ethylidene] - 2 - thio - - 2 : 4 - oxazoledione, prepared by refluxing together 2 - (w - acetanilidovinyl) - 3 - phenylbenzthiazolium iodide, 3 - ethyl - 2 - thio - 2 : 4 - oxazoledione, and triethylamine in ethyl alcohol ; (2) 11 - ethyl - 3 - phenylthia - 4<SP>1</SP> - carbocyanine perchlorate, prepared by refluxing together 2 - (w - acetanilidovinyl) - 3 - phenylbenzthiazolium iodide and lepidine iodide in pyridine ; and (3) 3 - ethyl - 5 - [(3 - phenyl - 2 - benzthiazolyidine) - ethylidene] - rhodanine. Specification 403,845 is referred to.