Patent GB-466246-A (GB)
Title: Improvements in the manufacture of carbocyanine dyes
IPC: C09B23/06
Filed: 1935-08-15
Abstract: Carbocyanine dyes are made by condensing a quaternary salt of an aryloxazole, arylthiazole or arylselenazole or of a thiazoline containing a reactive alkyl group attached to the carbon atom in a -position to the azoline nitrogen atom, with an arylthiazoline or an arylselenazoline having a ketonic alkacylmethylene group attached to the carbon atom in a -position to the azoline N-atom and an alkyl group attached to the azoline nitrogen atom. Chain-substituted symmetrical or unsymmetrical carbocyanine dyes are obtained.  In examples, (a) 1-acetylmethylene-2-methylbenzothiazoline is condensed with 1-methylbenzthiazole ethiodide in acetic anhydride; (b) 1-acetylmethylene - 2 - ethylbenzthiazoline is similarly condensed with 1 : 5-dimethylbenzthiazole ethiodide, 2-methyl-b -naphthathiazole ethyl p-toluenesulphonate, 2-methyl-b -naphthoxazole methyl or ethyl p-toluenesulphonate or 2-methylthiazoline; (c) 2-methyl-1-propionylmethylenebenzthiazoline with 4-chlor-1-methylbenzthiazole ethyl p-toluenesulphonate, 2-methyl-b -naphthathiazole ethyl p-toluenesulphonate or 1-methylbenzoxazole ethiodide; (d) 2-allyl-1-propionylmethylenebenzthiazoline with 2-methyl-b -naphthathiazole methyl-p-toluenesulphonate; (e) 2-ethyl-1-propionylmethylenebenzthiazoline is condensed in propionic anhydride with 1-methylbenzoxazole ethiodide; (f) 1-propionylmethylene-2-n-propylbenzthiazoline is condensed in acetic anhydride with 1-methylbenzselenazole ethiodide; (g) 4 - chlor - 2 - ethyl - 1 - propionylmethylenebenzthiazoline with 2-methyl-b -naphthathiazole ethyl-p-toluenesulphonate; (h) 2-acetylmethylene - 1 - ethyl - b  - naphthathiazoline with 1-methylbenzthiazole ethyl-p-toluenesulphonate, 1-ethylbenzthiazole ethiodide, 1-methyl-a -naphthathiazole ethyl-p-toluenesulphonate, 2 - methyl - b  - naphthathiazole ethyl - p - toluenesulphonate, 1 - methylbenzoxazole ethiodide, 1 - methyl - a  - naphthoxazole ethyl-p-toluenesulphonate or 1-methylbenzselenazole ethiodide; (i) 1-ethyl-2-propionylmethylene - b  - naphthathiazoline with 1 - methylbenzthiazole ethiodide or n - propiodide, 4 - chlor - 1 - methylbenzthiazole ethyl - p - toluenesulphonate, 1-methylbenzoxazole ethiodide or 1-methylbenzselenazole ethiodide; (j) 1-methyl-2-propionylmethylene - b  - naphthathiazoline with 4-chloro - 1 - methylbenzthiazole methyl - p-toluenesulphonate; (k) 2-ethyl-1-propionylmethylenebenzselenazoline with 2 - methyl b -naphthathiazole methyl p-toluenesulphonate; (l) 1 - acetylmethylene - 2 - ethylbenzselenazoline with 1 - methylbenzoxazole ethiodide. Dyes containing higher alkyl groups in the 8-position may also be prepared, e.g. when 2 - ethyl - 1 - lauroylmethylene benzthiazoline is treated with 1-methylbenzthiazole ethyl-p-toluenesulphonate an intense colouration is formed.  The dyes are useful for sensitizing photographic silver salt emulsions.  They may also be used in the construction of light filters or as colouring matters for textiles, particularly cellulose acetate artificial silk. Specification 466,269 is referred to.  Quaternary salts.--4 - chlor - 1 - methylbenzthiazole methyl- or ethyl - p - toluenesulphonate is made by heating the thiazole with methyl- or ethyl-p-toluenesulphonate.  2 - Methyl - b  - naphthoxazole ethyl - p-toluenesulphonate is similarly made from 2 - methyl - b  - naphthoxazole and 1-methyl-a  - naphthoxazole ethyl - p - toluenesulphonate from 1 - methyl - a  - naphthoxazole.  2-Methylthiazoline ethyl-p-toluenesulphonate is similarly made from the corresponding thiazoline.  According to the Provisional Specification a -acylmethylene derivatives including a -arylacyl compounds are used as starting materials.  In an example, 1-benzoylmethylene-2-ethylbenzthiazoline is condensed with 1-methylbenzthiazole ethiodide in acetic anhydride.