Cacodylic acid

Cacodylic acid
Cacodylic acid
CAS number 75-60-5 YesY
PubChem 2513
ChemSpider 2418 YesY
EC number 200-883-4
DrugBank DB02994
KEGG C07308 YesY
ChEBI CHEBI:29839 YesY
RTECS number CH7525000
Jmol-3D images Image 1
Molecular formula C2H7AsO2
Molar mass 137.9977 g/mol
Appearance White crystals or powder
Density > 1.1 g/cm3
Melting point

192 - 198 °C

Boiling point

> 200 °C

Solubility in water 667 g/l
Acidity (pKa) 6.3
MSDS External MSDS
EU classification Very Toxic T+
R-phrases R26/27/28, R40
 YesY acid (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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.



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:[1][2]

(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


  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
  • Kenyon, E. M.; Hughes, M. F. (2001). "A Concise Review of the Toxicity and Carcinogenicity of Dimethylarsenic Acid". Toxicology 160 (1-3): 227–236. doi:10.1016/S0300-483X(00)00458-3. 
  • Elschenbroich, C; Salzer, A. (1992) Organometallics, 2nd Edition
  • Bunsen Biography

External links

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Look at other dictionaries:

  • Cacodylic acid — Cacodylic Cac o*dyl ic, a. (Chem.) Of, pertaining to, or derived from, cacodyl. [1913 Webster] {Cacodylic acid}, a white, crystalline, deliquescent substance, {(CH3)2AsO.OH}, obtained by the oxidation of cacodyl, and having the properties of an… …   The Collaborative International Dictionary of English

  • cacodylic acid — dimetilarsinatorūgštis statusas T sritis chemija formulė (CH₃)₂AsO₂H atitikmenys: angl. cacodylic acid; dimethylarsinic acid rus. диметиларсиновая кислота; какодиловая кислота ryšiai: sinonimas – kakodilo rūgštis …   Chemijos terminų aiškinamasis žodynas

  • cacodylic acid — Prepared by treating cacodyl and cacodyl oxide with mercuric oxide, and forms cacodylates with various bases that were used in skin diseases, tuberculosis, malaria, and other affections in which arsenic was considered of value. SYN:… …   Medical dictionary

  • cacodylic acid — |kakə|dilik noun Etymology: part translation of German kakodylsäure, from kakodyl + säure acid : a crystalline deliquescent compound (CH3)2AsOOH obtained by oxidizing cacodyl oxide and used in medicine in the form of its salts; dimethyl arsinic… …   Useful english dictionary

  • cacodylic acid — noun dimethylarsenic acid, (CH)AsO OH, whose derivatives, the cacodylates, were once used as herbicides See Also: cacodyl …   Wiktionary

  • cacodylic acid — [ kakə(ʊ)dʌɪlɪk, dɪlɪk] noun Chemistry a toxic crystalline acid containing arsenic, used as a herbicide …   English new terms dictionary

  • cacodylic acid — noun Etymology: German Kakodyl the radical As(CH3)2, from Greek kakōdēs foul smelling, from kak + ōdēs (akin to Greek ozein to smell) more at odor Date: 1850 a toxic crystalline compound of arsenic C2H7AsO2 used especially as an h …   New Collegiate Dictionary

  • cacodylic acid — a colorless, crystalline, deliquescent, poisonous solid, (CH3)2AsOOH, used chiefly in the manufacture of dyes and as an herbicide. [1840 50] * * * …   Universalium

  • Cacodylic — Cac o*dyl ic, a. (Chem.) Of, pertaining to, or derived from, cacodyl. [1913 Webster] {Cacodylic acid}, a white, crystalline, deliquescent substance, {(CH3)2AsO.OH}, obtained by the oxidation of cacodyl, and having the properties of an exceedingly …   The Collaborative International Dictionary of English

  • cacodylic — adjective Of or pertaining to cacodylic acid or its derivatives …   Wiktionary

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