thioindigon.

1906 Textile Colorist XXVIII. 321/1 Messrs. Kalle & Co. Aktiengesellschaft, have placed upon the market, under the name of Thio Indigo Red B, a new coloring matter, which like Indigo is admirably suited for dyeing the various textile fibres and for calico printing.

1923 Thorpe & Ingold Vat Colours vi. 131 The following aromatic bases have been converted..into the corresponding aromatic thioglycollic acids, which have been transformed..into thioindigos.

1951 R. E. Kirk & D. F. Othmer Encycl. Chem. Technol. VII. 823 Thioindigo..forms brownish-red metallic crystals when recrystallized from xylene or other organic solvents... On reduction with sodium hyposulfite in the presence of alkali, it forms a pale yellow leuco compound, Thioindigo White.

1961 S. R. Cockett & K. A. Hilton Dyeing of Cellulosic Fibres v. 185 Thio-indigo is an important basic structure for a number of useful vat dyes.

1943 Thorpe's Dict. Appl. Chem. (ed. 4) VI. 454/1 This process has been applied..for preparing the orange thio~indigoid dye from p-phenetioline.

1951 R. E. Kirk & D. F. Othmer Encycl. Chem. Technol. VII. 824 Although the fastness of thioindigoids does not in general approach that of the anthraquinone vat dyes, the brightness and clarity of shade are in many cases considerably superior.

1952 K. Venkataraman Chem. Synthetic Dyes II. xxxiii. 1004 Apart from indigo itself, the thio~indigoids constitute a much more important series than the indigoids.

1970 K. Venkataraman Chem. Synthetic Dyes III. i. 36 With the exception of halogenated indigo and a few thioindigoids..the indigoid group is steadily declining in commercial importance.

1972 Materials & Technol. V. xi. 358 Thioindigoid reds and maroons are vat dyestuff pigments with good light-fastness in full colours and reduced shades and excellent acid and alkali resistance.