Patent GB-436941-A (GB)
Title: Method for the sensitising of photographic emulsions and manufacture of dyes therefor
IPC: G03C1/20
Filed: 1934-01-16
Abstract: 4.4<1>-Tricarbocyanine dyes having a substituted or unsubstituted quinoline nucleus, but unsubstituted in the 7-methenyl chain are prepared by condensing a quinoline containing a reactive methyl group in the g -position and otherwise substituted or unsubstituted with an arylido glutaconic aldehyde anil, the condensation being effected in presence of a strong organic base in acid - binding quantity and without heating, preferably at or near 0 DEG  C.  The strong organic bases suitable are those defined in Specification 408,571, viz. bases such as an alkylamine or piperidine or bases of similar strength, which bases are stronger than the pyridine bases.  The products sensitize photographic silver halide emulsions to the infra-red region of the spectrum.  In an example, lepidine ethiodide is condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine at 0 DEG  C.; lepidine methiodide and alliodide may similarly be condensed and triethylamine may replace piperidine. A further example describes the sensitizing of an emulsion by addition of 0,2--2,0 milligramme of a dye per litre of emulsion to the uncast emulsion, the temperature being kept as low as possible; the dyes are preferably used when freshly prepared. Sensitizing data of the dyes prepared in example 1 are given.  A sample has been furnished under Sect. 2 (5) of 1.1<1>-di-n-butyl-4.4<1>-tricarbocyanine prepared by condensing lepidine-n-butyliodide with glutaconic aldehyde dianilide in presence of piperidine.  Specification 354,826 also is referred to.  The Specification as open to inspection under Sect. 91 relates to the manufacture of various types of cyanine dyes using as acid binding agent a strong organic base.  The latter include the aliphatic organic bases referred to in Specification 408,571 and also bases such as dimethylaniline, quinoline, quinaldine, methylpiperidine. The utility of these bases when employed in a number of cyanine dye manufactures is referred to and the examples comprise the following manufactures: (1) the processes described in the examples of Specification 408,571; (2) 1-methylbenzoxazole ethiodide condensed with 2-iodoquinoline ethiodide in presence of triethylamine, triethanolamine, or b -diethylaminoethyl alcohol; (3) 1-ethylbenzthiazole ethiodide condensed with 2-iodoquinoline ethiodide in presence of triethylamine; (4) a -picoline methiodide condensed with 2-iodopyridine methiodide in presence of triethylamine; (5) 2.4-dimethylthiazole ethiodide condensed with 2-iodopyridine methiodide in presence of triethylamine; (6) 2.4 - dimethylselenazole metho - p - toluenesulphonate and 2.4-dimethyloxazole metho-p-toluenesulphonate condensed with 2-iodopyridine methiodide in presence of triethylamine; (7) 1-methylbenzselenazole ethyl-p-toluene sulphonate condensed with quinoline ethiodide in presence of pyridine and triethylamine; (8) 1-ethylbenzthiazole ethiodide condensed with quinoline ethiodide in presence of pyridine and triethylamine; (9) 1-methylbenzoxazole ethiodide condensed with ethyl orthoacetate in presence of triethylamine; (10) 1-methylbenzoxazole methyl-p-toluenesulphonate condensed with ethyl orthopropionate in presence of triethylamine; (11) quinaldine ethyl-p-toluenesulphonate condensed with a -bromo-b -anilinoacrolein anil hydrobromide in presence of piperidine; (12) lepidine -etho-p-toluenesulphonate condensed with a -bromo-b -anilinoacroleinanil hydrobromide in presence of piperidine; (13) 1-methylbenzthiazole etho-p-toluenesulphonate condensed with an equimolar proportion of a -bromo-b -anilinoacrolein anil hydrobromide in acetic anhydride and the product condensed with 2-methylthiazoline methiodide in presence of triethylamine; (14) lepidine n-butyl iodide and n-propyl iodide condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine; (15) 2-methylthiazoline ethyl (and methyl) -p-toluenesulphonate condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine; (16) 2-methylthiazole etho-p-toluene sulphonate condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine; (17) 2.4 - dimethylthiazole metho - p - toluenesulphonate condensed as in (16); (18) 1-methyl-benzselenazole methyl-b -toluenesulphonate condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine; (19) 1-methylbenzthiazole alliodide condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine; (20) 1.3- and 1.5-dimethylbenzthiazole ethyl-p-toluenesulphonate condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine; (21) 1 - methyl - 5 - ethylbenzthiazole ethyl - p-toluenesulphonate condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine; (22) 4-chloro-1-methylbenzthiazole etho - p - toluenesulphonate condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine.  It is stated that all of the dyes described sensitize photographic emulsions for which purpose 5--100 milligrams of the dye are added to a litre of emulsion; the utility of the thiotricarbocyanines in this connection is stressed. Specifications 353,889, 354,826 and 369,947 also are referred to. The Specification as open to inspection under Sect. 91 in respect of Specification 1574/34, also relates to gelatino silver halide emulsions which contain a tricarbocyanine dye comprising two similar nuclei selected from the group consisting of thiazole, thiazoline and benzselenazole nuclei linked together by a 7-methenyl chain.  The indications for use of the products for sensitizing purposes are as set out in the accepted Specification.  This subject-matter does not appear in the Specification as accepted.