Cacodylic acid

From Wikipedia, the free encyclopedia
  (Redirected from Sodium cacodylate)
Jump to: navigation, search
Cacodylic acid
Structural formula
Ball-and-stick model
Identifiers
CAS number 75-60-5 YesY
PubChem 2513
ChemSpider 2418 YesY
UNII AJ2HL7EU8K YesY
EC number 200-883-4
DrugBank DB02994
KEGG C07308 YesY
ChEBI CHEBI:29839 N
RTECS number CH7525000
Jmol-3D images Image 1
Properties
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
Hazards
MSDS External MSDS
EU classification Very Toxic T+
R-phrases R26/27/28, R40
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
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.

History[edit]

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.

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

Cacodylic acid and its salts were incorporated into herbicides by large variety of manufacturers under numerous brand names. APC Holdings Corp. sold Cacodylic acid and its salts under the Phytar brand name.[1] The variety used in Vietnam (as Agent Blue) was Phytar 560G.[2]

Synthesis and reactions[edit]

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)2.

Cacodylic acid can be reduced to dimethylarsine (III) derivatives, which are versatile intermediates for the synthesis of other organoarsenic compounds:[3][4]

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

Health effects[edit]

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[edit]

References[edit]

  1. ^ Stanley A. Greene (2005). Sittig's Handbook of Pesticides and Agricultural Chemicals. William Andrew. p. 132. ISBN 978-0-8155-1903-4. 
  2. ^ Committee to Review the Health Effects in Vietnam Veterans of Exposure to Herbicides; Institute of Medicine (1994). Veterans and Agent Orange: Health Effects of Herbicides Used in Vietnam. National Academies Press. pp. 89–90. ISBN 978-0-309-55619-4. 
  3. ^ 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.
  4. ^ 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[edit]