Difference between revisions of "Arsanilic acid"
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Latest revision as of 12:12, 20 September 2010
| Arsanilic acid | |
|---|---|
| Chemical structure of arsanilic acid | |
| Ball-and-stick model of the solid-state zwitterionic structure of arsanilic acid | |
| 4-aminophenylarsonic acid | |
| Other names 4-Aminobenzenearsonic acid, 4-Aminophenylarsonic acid, 4-Arsanilic acid, Atoxyl | |
| style="background: #F8EABA; text-align: center;" colspan="2" | Identifiers | |
| CAS number | 98-50-0 |
| style="background: #F8EABA; text-align: center;" colspan="2" | 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 |
| style="background: #F8EABA; text-align: center;" colspan="2" | Hazards | |
| R-phrases | R23-R25,R50-R53 23/25-50/53 |
| S-phrases | S20S21S28S45S60-S61 |
| NFPA 704 | |
| style="background: #F8EABA; text-align: center;" colspan="2" | Related compounds | |
| Related compounds | phenylarsonic acid |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
| Infobox references | |
Arsanilic acid is the organoarsenic compound also called p-aminophenylarsenic 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.
Synthesis
Arsanilic acid was first reported in 1859 by Antoine Béchamp. Béchamp optimistically chose the name Atoxyl, referring to its reduced toxicity compared to arsenic. The original synthesis, which involved the reaction of aniline and arsenic acid, remains useful today:[2]
- C6H5NH2 + H3AsO4 → H2O3AsC6H4NH2 + H2O
History and uses
Arsanilic acid 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.
References
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- Atoxyl at Chemical Heritage More about the origins and uses of the medicine.
- Explorers of the Body Some info about sleeping sickness and atoxyl.
- Arsonic Acid poisoning information.
- Ihde, Aaron J. The Development of Modern Chemistry, Dover, New York, 1984. pp. 697-698.ar:أتوكسيل
- ↑ R. H. Nuttall and W. N. Hunter (1996). "p-Arsanilic Acid, a Redetermination". Acta Cryst. C52: 1681–1683. doi:10.1107/S010827019501657X.
- ↑ W. Lee Lewis and H. C. Cheetham (1941), "Arsanilic Acid", Org. Synth.; Coll. Vol., 1: 70 Missing or empty
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