Patent GB-571077-A (GB)
Title: Improvements in cyanine dyes and in intermediates therefor, and in photographic emulsions sensitized with the dyes
IPC: C09B23/01
Filed: 1944-04-28
Abstract: Symmetrical and unsymmetrical cyanine dyes (including simple cyanine, carboxyanine, isocyanine, dicarbocyanine, tricarbocyanine, tetracarbocyanine, pentacarbocyanine, merocyanine, neocyanine, and polymeric cyanine dyes) are prepared from 2-methyl-4-a -furylthiazoles (including the corresponding coumaryl compounds) by customary methods.  With unsymmetrical dyes, the second heterocyclic base may be any of the usual bases, a large number of which are specified.  Cyanines may be obtained by reaction of a quaternary salt of a 2-methyl-4-a -furylthiazole with a thioether, e.g. 1-methylmercapto or 1-ethylmercapto-quinoline-, benzthiazole-, benzoxazole-, benzselenezole-, naphthathiazole or -naphthoxazole. Carbocyanines may be obtained by condensation with an ortho ester of a carboxylic acid such as trimethyl orthopropionate methyldiethyl orthon - caproate, methyldiethyl orthoisocaproate, trimethyl orthovalerate, trimethyl orthoformate, trimethyl orthobenzoate, trimethyl ortho-p-toluate, trimethyl ortho - g  - phenoxybutyrate, and trimethyl orthophenylacetate. Tetracarbocyanine dyes may be obtained by condensing the quaternary salts alone or with other known cyclammonium compounds by reaction with 4-acetoxy- (or 4-benzoxy-)-D 3-5-heptadiene - 1 : 7 - dial - di - tetrahydroquinolide acid salts, and pentacarbocyanines by condensing with 4-acetoxy- (or 4-benzoxy-)-D 3-5 : 7 - nonatriene-1 : 9-dial-ditetrahydroquinolide acid salts.  Examples are given of the preparation and photographic sensitizing properties of (a) a symmetrical carbocyanine dye by refluxing 2 - methyl - 4 - a  - furylthiazole ethyl p - toluene - sulphate and ethyl orthoformate in dry pyridine; (b) an unsymmetrical carbocyanine dye by refluxing 2-methyl-4-a -furylthiazole-ethyl-p-toluenesulphonate and 2-anilidovinyl - b  - naphthathiazole ethiodide in pyridine; (c) an unsymmetrical carbocyanine dye by refluxing 2 - methyl - 4 - a  - furylthiazole - ethyl - p - toluene - sulphonate and 2- anilidovinyl - a  - naphtha - thiazole in pyridine; (d) an unsymmetrical carbocyanine dye by refluxing 2-methyl-4-a -furylthiazole - ethyl - p - toluenesulphonate and 2-anilidovinylbenzthiazole in pyridine; (e) an unsymmetrical carbocyanine dye by refluxing 2 - methyl - 4 - a  - furylthiazole - ethyl - p - toluene - sulphonate and 2 - anilidovinyl - a  - naphthselen - azole diethyl sulphate in pyridine; (f) of cyanine dyes prepared by refluxing 2-methyl-4-a  - furylthiazole-ethyl - p - toluenesulphonate and 2 - methylmercaptoquinoline - ethyl - p - toluene - sulphonate or 2-methylmercapto-6-methoxyquinoline diethyl sulphate with alcohol and triethylamine; (g) of a symmetrical carbocyanine dye obtained by refluxing 2-methyl-4-a -benzofurylthiazole-ethyl-p-toluenesulphonate with ethyl orthoformate and pyridine; (h) of unsymmetrical cyanine dyes obtained by refluxing 2-methyl-4-a -benzofurylthiazole ethiodide with 2-methylmercaptoquinoline-ethyl-p-toluenesulphonate or 2 - methylmercapto - 6 - methoxyquinoline diethyl sulphate or 2-methylmercapto-6-methylquinoline ethiodide together with triethylamine or pyridine; (i) of unsymmetrical carbocyanine dyes obtained by refluxing 2-methyl-4-a -benzofurylthiazole ethiodide with 2-anilidovinylbenzthiazole ethiodide or 2-anilidovinylbenzselenazole ethiodide or 2-anilidovinyl - a  - naphthathiazole ethiodide or 2-anilidovinylquinoline ethiodide and with pyridine; (f, j) of a meso-chloro-substituted dicarbocyanine obtained by refluxing together 2-methyl-4-a -furylthiazole-ethyl-p-toluenesulphonate, a -chloro-b -anilinoacroleinanil, alcohol, and triethylamine; (k) of tricarbocyanines obtained by refluxing 2-methyl-4-a -furylthiazole-ethyl-p-toluenesulphonate or 2-methyl-4-a -benzofurylthiazole-ethyl-p-toluenesulphonate with pentadienedianil hydrochloride, alcohol, and triethylamine; (l) of an unsymmetrical cyanine dye obtained by refluxing 2-methyl-4-a -furyl-5-carbethoxythiazole dimethyl sulphate, 2 - methylmercaptoquinoline ethobromide, alcohol, and triethylamine; and (m) of a symmetrical carbocyanine dye obtained by refluxing 2 - methyl - 4 - a  - furyl - 5 - carbethoxy - thiazole dimethyl sulphate with ethyl orthoformate and pyridine.  2-Methyl-4-a -furylthiazole is prepared by brominating a carbon disulphide solution of furyl methyl ketone with a carbon disulphide solution of bromine, refluxing the product with thioacetamide, and distilling.  2-Methyl-4-a -benzofurylthiazole, 2-methyl-4-a -furyl-5-carbethoxythiazole, 2-methyl-4-a -benzofuryl-5-carbethoxythiazole and 2-methyl-4 : 5-di-a -furylthiazole are similarly prepared from 2-acetylcounarone, furoylacetic ester, benzofuroylacetic ester and desoxyfuroin respectively.  2 - Methyl - 4 - a  - benzofurylthiazole ethiodide is prepared by heating together 2-methyl-4-a -benzofurylthiazole and ethyl iodide under pressure.  Benzofuroylacetic ester is prepared by reacting the sodium salt of salicylaldehyde with bromacetoacetic ester.  The dyes may be used as sensitizing, filter, or antihalation dyes. Specifications 465,823, 487,051, 489,161, 489,335 and 512,542 are referred to.  The Specification as open to inspection under Sect. 91 refers also to the use of the corresponding b  : b  - naphthofuryl-, isonaphthofuryl-, a -naphthofuryl-, a  : b -isonaphthofuryl-, b -naphthofuryl-, and anthracenofuryl compounds and to merocyanine dyes formed by condensing the 2-methyl-4-a -furylthiazoles with five- and six-membered heterocyclic ring compounds containing the group C=Te.  This subject-matter does not appear in the Specification as accepted.