Patent GB-190416268-A (GB)
Title: Manufacture of Sulphur Dyes and of Materials for their Production.
Filed: 1904-07-22
Granted: 1905-06-08
Abstract: 16,268. Abel, C. D., [Akt.-Ges. f³r Anilin- Fabrikation]. July 22. Indophenols, which are parent substances for sulphuretted dyes, are prepared from glycine derivatives and #-sulphonates of aromatic bases of the benzene and naphthalene series having free ppositions. General methods are employed, namely, either joint oxidation of a p-amidophenol with the appropriate alphylglycine or #-sulphonate, or treating the latter with p-nitrosophenols in the presence of hydrochloric or sulphuric acid. Bodies of the following form are obtained:-O : R : N.R1. NH.OH2.COOH and O : R : N.R1.NH.CH2.SO3H. For example, to prepare the indophenol O : C6H4 : N.C6H3(CH3).NH.CH2.COOH, (N : CH3 : NH #1: 3 : 4), p-amidophenol and o-tolylglycine, obtained by treating o-toluidine with monochloracetic acid, are dissolved in dilute sulphuric acid and mixed, while stirring well, with a concentrated aqueous solution of sodium bichromate. On the completion of the reaction, the indophenol is separated from the deep-blue solution, preferably by adding sodium acetate and filtration, as a dark-brown paste. It is somewhat soluble in water, the solution becoming violet-blue with alkali, and dissolves to a green solution in strong sulphuric acid. Or p.nitrosophenol is stirred gradually into a cooled solution of o-tolylglycine in 70 per cent. sulphuric acid or strong hydrochloric acid. Separation is effected by pouring the resulting deep-blue solution into an aqueous solution of sodium carbonate mixed with ice. The indophenol from p-nitroso-o-cresol may be similarly obtained. To prepare the indophenol from a-naphthylglycine, obtained similarly to b-tolylglycine, and p-amidophenol, aqueous solutions of the glycine with sodium carbonate and the amidohydrochloride with caustic soda are mixed and cooled to 0‹ C. The mixture is oxidized with dilute sodium hypochlorite solution and, an intense bordeaux-red colour being assumed, the indophenol is separated with sodium bicarbonate and salt. The indophenol from o-chlor-p-amidophenol may be similarly obtained. To produce an indophenol from monomethylaniline-#-sulphonic acid, aqueous solutions of the sodium sulphonate and p-amidophenolhydrochloride are mixed and cooled to 0‹ C. Oxidization is effected with a solution of potassium bichromate in dilute sulphuric acid. The resulting green-blue precipitate is filtered off and gives intense blue and violet solutions in soda and caustic soda lyes respectively. Dyes, artificial.-Before preparing the sulphuretted dyes, it is generally preferable to reduce the indophenol to the leuco compound. Thus, an aqueous sodium sulphide solution of the firstdescribed indophenol precipitates the leuco compound, after filtration, upon addition of sodium bicarbonate. This leuco compound is boiled for twenty-four hours under a reflux condenser with a solution prepared by adding hot water to suitable proportions of crystallized sodium sulphide and sulphur melted together. The dye is precipitated by diluting with water and blowing air through, and is then filtered and dried. It dyes unmordanted cotton fast and clear deep-blue shades in a sodium-sulphide bath. The boiling point of the solution of sodium polysulphide may be raised by adding glycerine. The sulphuretted dye may be also made in alcoholic solution. Sulphuretted dyes from the indophenols, derived from o-tolylglycine and the nitroso-cresol, and from a-naphthylglycine and the chloramidophenol, are similarly prepared, and dye unmordanted cotton respectively dark-blue and blue-green.