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Cacodylic acid

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Cacodylic acid
Names
IUPAC name Dimethylarsinic acid
Other names Dimethylarsenic acid, Cacodylic acid, Hydroxydimethylarsine oxide, Arsecodile, Ansar, Silvisar, Phytar 560, DMAA, UN 1572
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.000.804 Edit this at Wikidata
EC Number
  • 200-883-4
KEGG
PubChem CID
RTECS number
  • CH7525000
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C2H7AsO2/c1-3(2,4)5/h1-2H3,(H,4,5)Key: OGGXGZAMXPVRFZ-UHFFFAOYSA-N
  • InChI=1/C2H7AsO2/c1-3(2,4)5/h1-2H3,(H,4,5)Key: OGGXGZAMXPVRFZ-UHFFFAOYAP
SMILES
  • O=(O)(C)C
Properties
Chemical formula C2H7AsO2
Molar mass 137.9977 g/mol
Appearance White crystals or powder
Density > 1.1 g/cm
Melting point 192 - 198 °C
Boiling point > 200 °C
Solubility in water 667 g/l
Acidity (pKa) 6.3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

Cacodylic acid is the chemical compound with the formula (CH3)2AsO2H. Derivatives of cacodylic acid, cacodylates, were frequently used as herbicides. For example, "Agent Blue," one of the chemicals used during the Vietnam War, is a mixture of cacodylic acid and sodium cacodylate. Sodium cacodylate is frequently used as a buffering agent in the preparation and fixation of biological samples for electron microscopy.

History

Significant early research into cacodyls was done by Robert Bunsen at the University of Marburg. Bunsen said of the compounds, "the smell of this body produces instantaneous tingling of the hands and feet, and even giddiness and insensibility...It is remarkable that when one is exposed to the smell of these compounds the tongue becomes covered with a black coating, even when no further evil effects are noticeable". His work in this field led to an increased understanding of the methyl radical.

Cacodyloxide, ((CH3)2As)2O, is often considered the first organometallic compound to be prepared synthetically.

Synthesis and reactions

In the 18th century it was known that combining As2O3 and four equivalents of potassium acetate (CH3CO2K) gives a product called "Cadet's fuming liquid" which contains cacodyl oxide, ((CH3)2As)2O and cacodyl, ((CH3)2As).

Cacodylic acid can be reduced to dimethylarsine (III) derivatives, which are versatile intermediates for the synthesis of other organoarsenic compounds:

(CH3)2AsO2H + 2 Zn + 4 HCl → (CH3)2AsH + 2 ZnCl2 + 2 H2O
(CH3)2AsO2H + SO2 + HI → (CH3)2AsI + SO3 + H2O

Health effects

Cacodylic acid is highly toxic by ingestion, inhalation, or skin contact. Once thought to be a byproduct of inorganic arsenic detoxification, it is now believed to have serious health consequences of its own. It has been shown to be teratogenic in rodents, most often causing cleft palate but also fetal fatality at high doses. It has been shown to be genotoxic in human cells, causing apoptosis and also decreased DNA production and shorter DNA strands. While not itself a strong carcinogen, cacodylic acid does promote tumors in the presence of carcinogens in organs such as the kidneys and liver.

See also

References

  1. Feltham, R. D.; Kasenally, A. and Nyholm, R. S., "A New Synthesis of Di- and Tri-Tertiary Arsines", Journal of Organometallic Chemistry, 1967, volume 7, 285-288.
  2. Burrows, G. J. and Turner, E. E., "A New Type of Compound containing Arsenic", Journal of the Chemical Society Transactions, 1920, 1374-1383

External links

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