Phenylarsonic acid is the chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 with the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 C₆H₅AsO(OH)₂, commonly abbreviated PhAsO₃H₂. This colourless solid is an organic derivative of arsenic acid

Arsenic acid

Arsenic acid is the chemical compound with the formula H3AsO4. More descriptively written as AsO3, this colorless acid is the arsenic analogue of phosphoric acid. Arsenate and phosphate salts behave very similarly. Arsenic acid as such has not been isolated, but only found in solution where it...

, AsO(OH)₃, where one OH group has been replaced by a phenyl group. The compound is a buffering agent

Buffering agent

A buffering agent is a weak acid or base used to maintain the acidity of a solution at a chosen value. The function of a buffering agent is to prevent a rapid change in pH when acids or bases are added to the solution. Buffering agents have variable properties—some are more soluble than others;...

 and a precursor to other organoarsenic compound

Organoarsenic compound

Organoarsenic chemistry is the chemistry of compounds containing a chemical bond between arsenic and carbon. A few organoarsenic compounds, also called "organoarsenicals," are produced industrially with uses as insecticides, herbicides, and fungicides. In general these applications are declining in...

s, some of which are used in animal nutrition, e.g. 4-hydroxy-3-nitrobenzenearsonic acid

4-Hydroxy-3-nitrobenzenearsonic acid

4-Hydroxy-3-nitrobenzenearsonic acid is an organic compound that is widely used agriculturally as a chicken-feed additive. The molecule is a derivative of phenylarsonic acid . This organoarsenic compound, usually under the tradename Roxarsone, has attracted attention as a source of arsenic...

.

Preparation and structure

PhAsO₃H₂ can be prepared in several routes, but a common one entails treatment of phenyl diazonium salts with sodium arsenite

Arsenite

In chemistry an arsenite is a chemical compound containing an arsenic oxoanion where arsenic has oxidation state +3.The different forms of the anion are the next ones:* ortho-arsenite: AsO33-* meta-arsenite: AsO2-...

 (prepared from arsenious acid and base) in the presence of a copper(II) catalyst.

C₆H₅N₂⁺ + NaAsO₃H₂ → C₆H₅AsO₃H₂ + Na⁺ + N₂

Related derivatives are prepared similarly. It was first prepared by Michaelis and Loenser. X-ray crystallography indicates that the molecules are connected by hydrogen-bonds consistent with short distance of 2.5 Å separating the oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 atoms. The arsenic center is tetrahedral.

Related phenylarsonic acids

Several derivatives of phenylarsonic acid have been used as additives for animal feeds. These include 4-hydroxy-3-nitrobenzenearsonic acid

4-Hydroxy-3-nitrobenzenearsonic acid

4-Hydroxy-3-nitrobenzenearsonic acid is an organic compound that is widely used agriculturally as a chicken-feed additive. The molecule is a derivative of phenylarsonic acid . This organoarsenic compound, usually under the tradename Roxarsone, has attracted attention as a source of arsenic...

(3-NHPAA, or Roxarsone), p-arsanilic acid (p-ASA), 4-nitrophenylarsonic acid (4-NPAA), and p-ureidophenylarsonic acid (p-UPAA).