Synthesis of o-arsanilic acid

Preparation of o-arsanilic acid

Preparation of o-arsanilic acid

Preparation of o-arsanilic acid

To a cold solution of 300 g. of ferrous sulfate in 900 ml. of water is added 25% aqueous sodium hydroxide solution with vigorous agitation until the mixture is alkaline to litmus. A solution of 40 g. of o-nitrophenylarsonic acid in dilute sodium hydroxide is added immediately, and the mixture is agitated vigorously for 5 minutes and then filtered through a large Buchner funnel with water washing. The filtrate is made barely acid to litmus with hydrochloric acid. Sufficient barium chloride solution is added to the hot solution to precipitate the sulfate ion, and the barium sulfate is removed by filtration. The filtrate is concentrated under vacuum, and the precipitated sodium chloride is removed by filtration and washed with saturated sodium chloride solution until the volume of the filtrate is about 200 ml. The filtrate is acidified with hydrochloric acid to Congo red, and the precipitated o-aminophenylarsonic acid is filtered off and washed with ice water. The product weighs 27 g. (80%) and melts at 153°.

J. Am. Chem. Soc., 40, 1583 (1918).


(2-aminophenyl)arsonic acid



InChI Key


Canonical SMILES


Depositor-Supplied Synonyms

o-Arsanilic acid, 2-Aminophenylarsonic acid, 2045-00-3, 2-Aminobenzenearsonic acid, o-Aminobenzenearsonic acid, (2-aminophenyl)arsonic acid, Arsenical, Arsonic acid,As-(2-aminophenyl)-, 2-Arsanilic acid, ACMC-209fae, o-Aminophenylarsonic acid, AC1L2JDH, 2-Aminobenzinearsonic acid, UNII-4P7T2PH7DL, AC1Q5A6Z, 4P7T2PH7DL, 139025_ALDRICH, CHEMBL346468, SCHEMBL3264637, Jsp004182, CTK4E4248, NSC12611, EINECS 218-064-5, ANW-24084, AR-1K8700, NSC-12611, OR5474, AKOS009031463, RTR-032621, AN-50334, OR013494, OR173791, TR-032621, A0529, FT-0633997, Z3707, 33095-EP2311815A1, I01-10244, 3B3-030282

Removed Synonyms

CID73161, 64269-06-3

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