Synthesis of 4-diazobenzenesulfonic acid (diazosulfanilic acid)

Preparation of 4-diazobenzenesulfonic acid

Preparation of 4-diazobenzenesulfonic acid (diazosulfanilic acid)

Preparation of 4-diazobenzenesulfonic acid (diazosulfanilic acid)

10.5 grams (or 0.05 mole) of sulfanilic acid crystals (dihydrate) are dissolved in 100 ml of 2.5% sodium carbonate solution (or 2.65 grams of anhydrous sodium carbonate and 100 ml of water) by boiling. The solution is cooled and treated with 3.7 grams of sodium nitrite while stirring until it is dissolved. The solution is poured into a beaker containing about 50 grams of ice and 10 ml of concentrated hydrochloric acid. In a minute or two a powdery white precipitate of diazobenzene sulfonate is obtained. The 4-diazobenzenesulfonic acid is not collected but is used in the form of the suspension. It is more stable than most diazonium salts, and could be kept for a few hours in cold.

Experiments in Organic Chemistry, L. F. Fieser, 208, 1941





InChI Key


Canonical SMILES


MeSH Synonyms

4-sulphodiazobenzene, DABS, DASA, diazobenzene sulfonate, diazobenzenesulfonate, diazobenzenesulfonic acid, diazobenzenesulfonic acid, chloride, diazobenzenesulfonic acid, hydroxide, diazobenzenesulfonic acid, hydroxy inner salt, diazobenzenesulphonate, diazosulfanilic acid, p-diazoniumbenzenesulfonic acid, Pauly’s reagent, sulfanilic acid, diazonium salt

Depositor-Supplied Synonyms

Benzenediazonium, 4-sulfo-, 4-Sulfobenzenediazonium, Diazosulfanilic acid, Pauly’s reagent, 4332-41-6, Diazobenzenesulfonate, 4-Sulphodiazobenzene, Diazobenzenesulphonate, DABS, DASA, Diazobenzene sulfonate, 4-Sulfophenyldiazonium, AC1Q4PUQ, Benzenediazonium, p-sulfo-, AC1L27RW, SCHEMBL937040, Sulfanilic acid diazonium salt, UNII-Z0105S98AO, p-Diazoniumbenzenesulfonic acid, CTK4I7237, Diazonium salt of sulfanilic acid, Z0105S98AO, 305-80-6 (OH inner salt), AR-1H8516

Removed Synonyms

Diazobenzenesulfonic acid, CID67540, 2154-66-7, 47082-97-3

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