Patent GB-408571-A (GB)
Title: Improvements in the manufacture of cyanine dyes
IPC: C09B23/00
Filed: 1932-06-30
Abstract: Dyes of the cyanine type in the manufacture of which a basic condensing agent is employed to combine with liberated acid, are prepared in the presence of a "strong organic base" in acid-binding quantity.  The term "strong organic base" is a base such as an alkylamine or piperidine, or bases of similar strength (which bases are definitely stronger than the pyridine bases used hitherto).  A salt of such base with a weak acid may also be used, which compound may function as a base of equivalent strength. Mention is made of di- and triethylamines, n-butyl- and tri-n-butyl-amines, piperidine and N-methylpiperidine, triethanolamine, b -diethylamine ethyl alcohol, guanidine and guanidine carbonate as suitable substances.  Excluded from the scope of the invention is the use of piperidine in preparing 11-halogeno- and 11-nitro-dicarbocyanines, and in preparing a selenocarbocyanine as claimed in Specification 403,974, the use of diethylamine for producing 1 . 1<1> - diethylbenzthio - b  - methylheptacarbocyanine or 1 . 1<1> - diethyl - 6 . 6<1> - bisdiethylamino - benzthio - d  - methylheptacarbocyanine and dimethylamine for producing 1 . 1<1> - dimethyl - 4.4<1> - quino - d - methylheptacarbocyanine (Specification 394,537).  Higher yields of dyes often result by the use of these bases.  In examples: (1) quinaldine ethiodide is heated with 2 - iodoquinoline ethiodide in presence of triethylamine, tri-n-butylamine or guanidine carbonate; (2) 1-methylbenzthiazole ethyl-p-toluenesulphonate is condensed with 2-iodoquinoline ethiodide in presence of di- or triethylamine, b -diethylaminoethyl alcohol, or guanidine carbonate; (3) 1-methylbenzselenazole ethyl-p-toluenesulphonate is condensed with 2-iodoquinoline ethiodide in presence of triethylamine; (4) 2 . 3. 3<1>-trimethylindolenine methiodide is condensed with 2-iodoquinoline ethiodide in presence of triethylamine; (5) a -picoline methiodide is condensed with 2-iodoquinoline methiodide in presence of triethylamine; (6) 1 - methylbenzthiazole ethyl - p - toluenesulphonate and 2-iodopyridine ethiodide are condensed in presence of triethylamine to give a mixture of 2.2<1>-diethylthiocyanine iodide and 2 . 1<1> - diethylthio - 2<1> - pyridocyanine iodide; (7) 1-methylbenzthiazole ethiodide is condensed with quinoline ethiodide in presence of pyridine and triethylamine; (8) 1-methylbenzthiazole ethiodide is condensed with a  - bromo - b - anilinoacrolein anil hydrobromide in presence of piperidine to give a dicarbocyanine dye; (9) 1-methyl-a -naphthothiazole ethyl-p-toluenesulphonate is condensed in presence of piperidine with a  - bromo - b  - anilinoacrolein anil hydrobromide to give a dicarbocyanine dye; (10) 1-methylbenzthiazole ethiodide is condensed with glutaconic aldehyde dianilide hydrochloride in presence of triethylamine, n- - butylamine, tri - n - butylamine or piperidine to give a tricarbocyanine dye; 1-methyl-a -naphthothiazole ethiodide may be similarly condensed; (11) quinaldine ethyl-p-toluenesulphonate is condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine to give a tricarbocyanine dye; (12) 1 - methylbenzselenazole ethyl - p - toluenesulphonate is condensed with glutaconic aldehyde dianilide hydrochloride in presence of piperidine.  Specifications 351,555, 354,826, and 408 569 also are referred to.