10 g of p-toluidine is combined with 30 mL of ice-cold concentrated sulfuric acid with vigorous stirring and let to stand overnight, then immersed in an ice bath. A slow addition of 12 mL of 53% nitric acid in 15 mL of conc. sulfuric acid is started with vigorous stirring, the nitrating solution is added 1 mL at a time. The mixture is stirred for 4 h in the ice bath, then allowed to stand in a freezer (-18°C) for 9 h and subsequently poured into 150 mL of ice. The mixture is filtered, washed with some cold water and dried in open air. The product is obtained as a bisulfate salt.
The sulfonated product
Nitration of the sulfonated product
The crude product precipitated in water
The crude product