Patent GB-191018761-A (GB)
Title: Manufacture of a New Form of Indigo.
Inventor: IMRAY OLIVER
IPC: C09B7/00
Filed: 1910-08-09
Granted: 1911-08-03
Abstract: 18,761. Imray, O., [Farbwerke vorm. Meister, Lucius, & Br³ning]. Aug. 9. Indigo. - A form of indigo is obtained by separating indigo from its salts or leuco compounds in the presence of aminosulphonic acids containing benzyl residues, or salts of such acids. The aminosulphonic acids used have the general formula where SO3A=the sulphonic acid residue or a metal salt thereof; R=aryl, alkyl, or a residue derived therefrom; B = benzyl, halogenbenzyl, sulphobenzyl, or the like; r<1>=hydrogen, alkyl, aryl, benzyl, halogenbenzyl, sulphobenzyl, etc.; r<2> = alkyl; and r<3>=halogen, a sulphuric acid residue, an alkylsulphuric acid residue, or an arylsulphuric acid residue; r<2> and r<3> may be absent. The following acids are specified:- o-, m-, and p-benzylsulphanilic acids, benzylaniline sulphonic acid, benzylaniline disulphonic acids, dibenzylaniline mono- or di-sulphonic acids, sulphobenzylsulphanilic acids, benzylnaphthylamine sulphonic acids, benzylaminonaphtholsulphonic acids, for instance, the 2 : 5 : 7- acid, chlorbenzylsulphanilic acids, benzylchloraniline sulphonic acids, benzyltoluidine sulphonic acids, benzylxylidine sulphonic acids, benzyldimethylphenylammonium chloride mono- or disulphonic acids. According to examples:- (1) Synthetic or natural indigo is introduced into sulphuric acid containing benzylsulphanilic acid or its sodium salt, and the mixture is poured on ice, or the mixture is well cooled and dilute sulphuric acid or ice is added thereto; the paste is pressed, and washed until neutral, or may be neutralized with caustic soda, ammonia, etc.; the decomposition of the above mixture may be effected in presence of starch, carbohydrates, glycerin, kaolin, hydrated silicic acid, &c. (2) An indigo melt, alkali indoxyl, or indigo vat, is diluted with water, a salt of benzylsulphanilic acid &c. is added, and the indigo is precipitated by air or other oxidizing-agent. The indigo so prepared is readily reduced even by weak reducing-agents, such as the cold glucose vat or fermentation vat; the paste yields on dilution with water a blue liquid which, under a high-power microscope, shows as a milky emulsion; the diluted paste gives on filtration a blue liquid. The paste may be dried in air or vacuum or by heating, and may be mixed with inorganic or organic substances such as clay, kaolin, glycerin, a sugar, starch, &c. Specifications 23,122/99 and 12,854/05 are referred to. Sulphonic acids.-Benzylanilinesulphonic acid is obtained by sulphonating benzylaniline; benzylaniline disulphonic acids are obtained by benzylating aniline disulphonic acids; dibenzylaniline mono- and di-sulphonic acids are obtained similarly; sulphobenzylsulphanilic acids are obtained by treating aniline sulphonic acids with w-chlortoluene sulphonic acids; benzylnaphthylamine sulphonic acids, benzylaminonaphthol sulphonic acids, benzylchloraniline sulphonic acids are obtained by benzylating the parent bodies; benzyldimethylphenylammonium chloride mono- or di-sulphonic acids are made by sulphonating benzyldimethylphenylammonium chloride.