| Arsanilic acid | |
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4-aminophenylarsonic acid |
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Other names
4-Aminobenzenearsonic acid, 4-Aminophenylarsonic acid, 4-Arsanilic acid, Atoxyl |
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| Identifiers | |
| CAS number | 98-50-0 |
| PubChem | 6432805 |
| ChemSpider | 7111 |
| DrugBank | DB03006 |
| ChEBI | CHEBI:49477 |
| ChEMBL | CHEMBL351769 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C6H8AsNO3 |
| Molar mass | 217.054 g/mol |
| Appearance | white solid |
| Density | 1.957 g/cm3 |
| Melting point |
232 °C |
| Solubility in water | modest |
| Hazards | |
| R-phrases | R23-R25,R50-R53 23/25-50/53 |
| S-phrases | S20S21S28S45S60-S61 |
| Main hazards | Toxic |
| NFPA 704 |
0
2
0
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| Related compounds | |
| Related compounds | phenylarsonic acid |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Arsanilic acid is the organoarsenic compound also called p-aminophenylarsonic acid. This colourless solid was used as a drug in the late 19th and early 20th centuries but is now considered prohibitively toxic. Arsanilic acid is a derivative of phenylarsonic acid with an amine in the 4-position. It exists as a zwitterion, H3N+C6H4AsO3H−,[1] although it is typically represented with the non-zwitterionic formula, H2NC6H4AsO3H2.
Contents |
Arsanilic acid was first reported in 1859 by Antoine Béchamp. The original synthesis, which involved the reaction of aniline and arsenic acid, remains useful today:[2]
In his reports on the chemical, Béchamp optimistically chose the name Atoxyl, referring to its reduced toxicity compared to arsenic. Atoxyl was initially used in medicine to treat simple skin diseases. In 1905, two British physicians, H.W. Thomas and A. Breinl, reported that atoxyl was active against the trypanosomes of sleeping sickness. The effect was however not very pronounced and the necessary dosage was so high that toxic side effects far outweighed the benefits. It frequently caused blindness by damaging the optic nerve and other varied disorders. Nevertheless, the discovery of arsanilic acid's activity against trypanosomes was the basis for a major advance by the bacteriologist Paul Ehrlich. Ehrlich, who believed that the formula was incorrect, and the organic chemist Alfred Bertheim revised the structural assignment. The correct formula suggested new ways that the atoxyl molecule could be modified, and a series of such derivatives were then synthesized. Testing for anti-syphilitic activity was performed by Sahachiro Hata who worked in Ehrlich's lab. The result of this collaboration was the discovery of the drug Salvarsan in 1909, which also was later abandoned but which accelerated the growth of medicinal chemistry.
Although the practice is controversial, arsanilic acid and related compounds are sometimes used in treating dysentery in swine.