Reactions of the Sulphonic Group

Reaction CLU. Action of Sulphur and Sodium Sulphide on Aromatic Bases.—Aromatic amines usually react with sulphur when heated in presence of sodium sulphide to give compounds of complex structure, two nuclei joining together through the -atom. Several compounds 

The dyestufEs produced are of various shades generally speaking, diphenylamines give blue and black dyes, toluidines yellow and brown, and diamines red dyes. 

22 gms. of diphenylamine, 8-2 gms. of sulphur, and 3 2 gms. of anhydrous aluminium chloride are melted together. The reaction sets in at 140°—150° with rapid evolution of sulphuretted hydrogen by lowering the temperature a few degrees the reaction can be slackened. When it has 

Preparation 302. — Dehydrothio-p-toluidine (Y-amino-l-phenyl-5-methylbemotkiazole sulphonate). 

107 gms. p-toluidine are heated with 70 gms. powdered sulphur (not flowers of sulphur) and 1 gm. sodium carbonate (to remove acidic substances in the sulphur) to 180° in a sulphonating pot fitted with a good agitator and reflux condenser. The H2S which is evolved is absorbed by a tower filled with lumps of moist caustic soda. The temperature is raised to 220° after about 8 hours, by which time the evolution of H2S slackens, and kept at 220° for 5 hours. The evolution of H2S now practically ceases, and the melt is then poured on to a tray to solidify. 

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