In the 18th century it was found that combining
arsenic trioxide () and four equivalents of
potassium acetate () gives a product called "
Cadet's fuming liquid" which contains
cacodyl oxide, and
cacodyl, . Early research into "
cacodyls" was reported 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 group. Cacodyl oxide, , is often considered the first
organometallic compound to be prepared synthetically. Cacodylic acid and its salts were incorporated into
herbicides by a large variety of manufacturers under numerous brand names. APC Holdings Corp. sold cacodylic acid and its salts under the
Phytar brand name. The variety Phytar 560G, a mixture of cacodylic acid and sodium cacodylate, was used during the
Vietnam War as a
defoliant under the name "
Agent Blue". ==Reactions==