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