Hydrochloric Acid → Benzenesulfonic acid, 2-amino-5-nitro-

Participants

Reaction Steps

An aqueous solution of 7 parts of sodium nitrite is added to 18.6 parts of 4-methylsulfonylaminoaniline in 50 parts by volume of 5N hydrochloric acid at 0°-5° C. The diazo solution is then poured into a stirred suspension, in 1,000 parts of water, of the coupling product obtained by diazotizing 23.4 parts of 2-hydroxy-3-amino-5-nitrobenzenesulfonic acid in a conventional manner and coupling the product to 11 parts of resorcinol in a medium rendered alkaline with sodium carbonate. After the addition, the pH is increased to 9, and the mixture is stirred until coupling is complete. A diazo solution obtained from 21.8 parts of 2-amino-5-nitrobenzenesulfonic acid in a conventional manner is then allowed to run into the mixture at pH 9-9.5, and stirring is continued until the coupling is complete. The resulting dye is complexed with 34 parts of iron(III) chloride in a conventional manner, and the iron complex of the compound of the formula ##STR204## is isolated; this product gives lightfast and wetfast dark brown dyeings on leather.

Provenance & Evidence