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Arsanilic acid is the organoarsenic compound
Organoarsenic compound

Organoarsenic chemistry is the chemistry of Chemical compound containing a chemical bond between arsenic and carbon. A few organoarsenic compounds, also called "organoarsenicals," are produced industrially with uses as insecticides, herbicides, and fungicides....
 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
Phenylarsonic acid

Phenylarsonic acid is the chemical compound with the chemical formula C6H5AsO2, commonly abbreviated PhAsO3H2....
 with an amine
Amine

Amines are organic compounds and functional groups that contain a base nitrogen atom with a lone pair. Amines are derivative s of ammonia, wherein one or more hydrogen atoms are replaced by organic substituents such as alkyl and aryl groups....
 in the 4-position. It exists as a zwitterion
Zwitterion

A zwitterion is a chemical compound that carries a total net charge of 0, thus electrically neutral but carries Formal charge on different atoms....
, H3N+C6H4AsO3H-, although it is typically represented with the nonzwitterionic formula, H2NC6H4AsO3H2.

nilic acid was first reported in 1859 by Antoine Béchamp
Antoine Béchamp

Pierre Jacques Antoine B?champ was a French biology. He studied silkworm parasites, and was the first to synthesise Atoxyl....
.






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Arsanilic acid is the organoarsenic compound
Organoarsenic compound

Organoarsenic chemistry is the chemistry of Chemical compound containing a chemical bond between arsenic and carbon. A few organoarsenic compounds, also called "organoarsenicals," are produced industrially with uses as insecticides, herbicides, and fungicides....
 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
Phenylarsonic acid

Phenylarsonic acid is the chemical compound with the chemical formula C6H5AsO2, commonly abbreviated PhAsO3H2....
 with an amine
Amine

Amines are organic compounds and functional groups that contain a base nitrogen atom with a lone pair. Amines are derivative s of ammonia, wherein one or more hydrogen atoms are replaced by organic substituents such as alkyl and aryl groups....
 in the 4-position. It exists as a zwitterion
Zwitterion

A zwitterion is a chemical compound that carries a total net charge of 0, thus electrically neutral but carries Formal charge on different atoms....
, H3N+C6H4AsO3H-, although it is typically represented with the nonzwitterionic formula, H2NC6H4AsO3H2.

Synthesis

Arsanilic acid was first reported in 1859 by Antoine Béchamp
Antoine Béchamp

Pierre Jacques Antoine B?champ was a French biology. He studied silkworm parasites, and was the first to synthesise Atoxyl....
. Béchamp optimistically chose the name Atoxyl, referring to its reduced toxicity compared to arsenic. The original synthesis, which involved the reaction of aniline
Aniline

Aniline, phenylamine or aminobenzene is an organic compound with the Chemical formula C6H7N. It is the simplest and one of the most important aromatic amines, being used as a precursor to more complex chemicals....
 and arsenic acid
Arsenic acid

Arsenic acid is the chemical compound with the chemical formula H3AsO4. More descriptively written as AsO3, this colorless acid is the arsenic analogue of phosphoric acid....
, remains useful today:
C6H5NH2
Aniline

Aniline, phenylamine or aminobenzene is an organic compound with the Chemical formula C6H7N. It is the simplest and one of the most important aromatic amines, being used as a precursor to more complex chemicals....
  + 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
Sleeping sickness

Sleeping sickness or human African trypanosomiasis is a parasitic disease of people and animals, caused by protozoa of species Trypanosoma brucei and transmitted by the tsetse fly....
. The effect was however not very pronounced and the necessary dosage
Effective dose

An effective dose in pharmacology is the amount of medication that produces a therapeutic response in 50% of the people taking it, sometimes also called ED-50....
 was so high that toxic
Toxicity

Toxicity is the degree to which a substance is able to damage an exposed organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver ....
 side effects far outweighed the benefits. It frequently caused blindness
Blindness

Blindness is the condition of lacking visual perception due to physiological or neurological factors.Various scales have been developed to describe the extent of vision loss and define "blindness." Total blindness is the complete lack of form and visual light perception and is clinically recorded as "NLP," an abbreviation for "no ligh...
 by damaging the optic nerve
Optic nerve

The optic nerve, also called cranial nerve II, transmits visual information from the retina to the brain....
 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
Paul Ehrlich

Paul Ehrlich was a German scientist in the fields of hematology, immunology, and chemotherapy, and Nobel Prize in Physiology or Medicine. He is noted for his research in autoimmunity, calling it "horror autotoxicus"....
. 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
Syphilis

Syphilis is a sexually transmitted disease caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The route of transmission of syphilis is almost always through sexual contact, although there are examples of congenital syphilis via transmission from mother to child in utero....
 activity was performed by Sahachiro Hata
Sahachiro Hata

; was a Japan bacteriologist who developed the Arsphenamine drug in 1909 in the laboratory of Paul Ehrlich.Hata was born in Shimane Prefecture, and completed his medical education in Kyoto....
 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
Dysentery

Dysentery is a disorder of the digestive system that results in severe diarrhea containing mucus and/or blood in the feces. If untreated, Dysentery can be fatal....
 in swine.

External links

  • More about the origins and uses of the medicine.
  • Some info about sleeping sickness and atoxyl.
  • .
  • Ihde, Aaron J. The Development of Modern Chemistry, Dover, New York, 1984. pp. 697-698.