GB190112578A - New Sulpho Acids and Sulphur Dyestuffs. - Google Patents

Abstract

12,578. Shillito, T. R., [Aniline Colour and Extract Works, (formerly Geigy, J.R.)]. June 20. Dimethyl-p-amido-p-oxydialphylamine sulphonic acids are produced by acting upon dimethyl-pamidophenylquinoneimide, or homologous indophenols such as the dimethyl-p-amidophenyltoluquinone obtained from dimethyl-p-phenylenediamine and o-cresol, with a neutral sulphite, or with a bisulphite or sulphurous acid. The sulphonic acids produced when a neutral sulphite is employed are sparingly soluble in water, but those produced by means of a bisulphite, or sulphurous, acid are very soluble in cold water. The reaction takes place at the ordinary temperature, or, more rapidly, at 50‹-60‹ C., or at boiling point. Dyes, artificial.-New sulphur dyes, which dye unmordanted cotton fast blue shades, are produced by heating the foregoing sulphonic acids with alkali polysulphides at 120‹-200‹ C. The difficultlysoluble sulphonic acids are converted by this process at about 120‹-140‹ C. into pure blue dyes, and the soluble sulphonic acids and those derived from o-cresol are converted at a higher temperature into bluish-grey to dark blue dyes. The dye is separated from the melt by dissolving it in water, oxidizing by a current of air, and precipitating by addition of a solution of sodium hypochlorite ; or by dissolving the melt in water, precipitating the leuco compound by hydrochloric acid, and oxidizing it by air and caustic soda, or by sodium hypochlorite, peroxide of hydrogen, or other alkaline oxidizing-agent.