GB346243A - Manufacture of dyestuffs - Google Patents

Abstract

Gallocyanines; printing.-Simple gallocyanines derived from meta-substituted alkylaniline, and having the general constitution defined in the parent Specification, are converted into derivatives, which still retain the meta-substituent, by condensation with an aromatic hydroxy compound. The latter may contain sulphonic groups, or the products may be sulphonated, either in the lenco form or in the oxidized form, to render them soluble in water. The products, like those of the parent Specification, show greater resistance to reducing agents as compared with the corresponding dyes unsubstituted in the meta-position (see Specifications 24802/93, 15064/94, 16301/95, [all in Class 2, Acids and salts, Organic &c.], and 6272/09, [Class 2 (iii), Dyes &c.]), and are suitable for use in discharge printing. In examples, (1) the simple gallocyanines from nitrosodimethyl- or -diethyl-m-toluidine and gallomide are condensed with resorcin or with another aromatic hydroxy compound, such as b -resorcylic acid, pyrogallol or gallic acid, in the presence of hydrochloric acid; the products may be sulphonated by treating their dry-leaved compounds with sulphuric acid, and (2) the gallocyanine from nitrosodimethyl-m-toluidine and gallic acid is condensed with 2-naphthol-6-sulphonic acid in the presence of caustic soda or of an acid; other naphthol-sulphonic acids or aromatic oxycompounds may be used.