GB321155A - Manufacture of dyestuffs of the polymethine series - Google Patents

Abstract

321,155. Imray, O. Y., (Soc. of Chemical Industry in Basle). June 27, 1928. Cyclammonium polymethine compounds.-Dyestuffs are obtained by oxidizing, in a medium which is not alkaline, a condensation product produced : (1) by the action of formaldehyde (1 mol.) upon a methylene base of a cyclammonium salt having a reactive methyl group in the alphaposition (2 mols.), or (2) by removal of acid, by treatment with alkali, from the product produced from formaldehyde (1 mol.) and a cyclammonium salt having a reactive methyl group in the aposition (2 mols.). In examples, formaldehyde is condensed with 1 : 3 : 3-trimethyl-2-methyleneindolin in alcoholic solution, and the product, dissolved in benzene, oxidized by means of benzoquinone in the presence of acetic acid. The resulting addition product of 1 3 : 3 : 1<1> : 3'- : 3<1>- hexamethylstreptomonovinylene-2 : 2<1>-indocyanineacetate with hydroquinone may be treated with alkali to give the free base, which yields a hydrochlcride on dissolution in dilute hydrochloric acid; (2) lead peroxide is used for oxidation of the same condensation product; (3) methylenedi-quinaldine iodomethylate, prepared from formaldehyde (1 mol.) and quinaldineiodomethylate (2 mols.), in the presence of a small quantity of piperidine, is treated with 30 per cent caustic soda at 70-80‹ C. and the base, dissolved in chloroform, oxidized by means of quinone in the presence of acetic acid. The product is probably an addition product of hydroquinone and 1 : 1<1>-dimethylstreptomonovinylene - 2 : 2<1>- quinocyanineacetate. Methylene bases of trimethylindoleninium salts derived from o- and p-toluidine or other substitution products or homologues of aniline or of a- or #-naphthylamine may also be condensed with formaldehyde and then oxidized. The dyestuffs from o- and p-toluidine yield pure bluish red tints on cotton mordanted with tannin while the dyestuffs from # -naphthylamine dye this material violet tints having a reddish fluorescence. Instead of quinone, derivatives of quinone, e.g. 2 : 6-dichlorquinone, or nitroso compounds, metallic oxides and salts, oxygen or air may be used. Formic, propionic, benzoic, sulphuric and hydrochloric acids are mentioned as acids that may be used in place of acetic acid.