Ryan, Algar, and O'Connell — Syntheses of Some Neiv D//e.s. 91 



7. Coupling of Benzidine-Siilphone-Disulphonic Acid with " H-Acid" 

 ( 1 Amino-&-Naphthol-Z-§-Dmdphonic Acid). 



NH 2 OH S0 3 Na 



I. 



/\/\-N=N_/ \ / 



S0 3 NaJ N/ l x/ L S 03 N a \-< > 



The tetrazotised solution of benzidme-sulphone-disulphonic acid was 

 added slowly, with constant stirring, to a solution of " H-acid," which was 

 prepared by dissolving 40 grams of " H-acid " in 450 c.cs. of water, and 

 adding 40 grams of sodium carbonate, the mixture being cooled to 15° C. 

 When all was added, the mixture showed an alkaline reaction. The stirring 

 was maintained vigorously for five hours afterwards, when the liquid was 

 heated to 80° C, saturated with common salt, and filtered. It is a deep blue 

 amorphous powder, giving a deep blue colour in alkali solution and red in 

 acid solution. It was purified by separation on cooling from hot dilute 

 alcohol. The substance dyes cotton directly a light blue. 



•1880 substance gave 10 - 8 c.cs. moist nitrogen at 16° C. and 760 mm. P., 

 corresponding to N = 6 - 67, 

 C-BH, 6 N 6 25 NacS 7 requires N = 7'01. 



8. Coupling of Bcnzidinc-Sulplwnc-Bisulphonic Acid with Schaffers Acid 

 {fi-Naphthol-6-Monosulphonic Acid). 



OH S0 3 Na S0 3 Na OH 



_! l._ _l i_ 



/ \ N - N / ^ / \ N - N / \ 



/ \ \so/ / \ 



\_/ 2 \_/ 



I I 



S0 3 Na S0 3 Na 



A solution of Schaffers acid was prepared by dissolving 27 grams of the 

 acid in 200 c.cs. of water containing 35 grams of sodium carbonate, and 

 cooling the mixture to 50° C. The mixture was stirred vigorously by means 

 of a turbine, and the tetrazotised solution from 20 - 3 grams of benzidine- 

 sulphone-disulphonic acid was slowly added; the stirring being maintained 

 for five hours afterwards. On standing overnight the colouring matter was 

 heated to 80° C, and precipitated by the addition of common salt. It was 

 then filtered and dried. The compound was purified by heating with water 

 and a little alcohol, then filtering and allowing to cool when the dye stuff 



