Cacodylic acid
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| Names | |
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IUPAC name
Dimethylarsinic acid
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| Other names
Dimethylarsenic acid, Cacodylic acid, Hydroxydimethylarsine oxide, Arsecodile, Ansar, Silvisar, Phytar 560, DMAA, UN 1572
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| Identifiers | |
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3D model (Jmol)
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| ChEBI | |
| ChemSpider | |
| DrugBank | |
| ECHA InfoCard | 100.000.804 |
| EC Number | 200-883-4 |
| KEGG | |
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PubChem CID
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| RTECS number | CH7525000 |
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| Properties | |
| C2H7AsO2 | |
| Molar mass | 137.9977 g/mol |
| Appearance | White crystals or powder |
| Odor | odorless |
| Density | > 1.1 g/cm3 |
| Melting point | 192 to 198 °C (378 to 388 °F; 465 to 471 K) |
| Boiling point | > 200 °C (392 °F; 473 K) |
| 66.7 g/100 ml | |
| Solubility | soluble in ethanol, acetic acid insoluble in diethyl ether |
| Acidity (pKa) | 1.57 |
| -79.9·10−6 cm3/mol | |
| Structure | |
| triclinic | |
| Hazards | |
| Safety data sheet | External MSDS |
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EU classification (DSD)
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 T+ |
| R-phrases | R26/27/28, R40 |
| Lethal dose or concentration (LD, LC): | |
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LD50 (median dose)
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700 mg/kg (rat, oral) |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| 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.
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. The variety used in Vietnam (as Agent Blue) was Phytar 560G.
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.
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