Arsonic acid (functional group)
Arsonic acids are organoarsenic compounds containing the functional group -AsO(OH)2. They are arsenic analogues of phosphonic acids. Arsonic acids are generally weak acids.
The simplest arsonic acid is arsonous acid, HAsO(OH)2, though it exists predominantly in the tautomeric form arsenic acid, As(OH)3.
Organoarsonic acids feature a carbon atom directly bonded to the arsenic atom. They can be represented by the formula RAsO(OH)2, where R is an organic substituent (e.g., alkyl, aryl). They are commonly prepared by the Bart reaction, which involves the reaction of an aryl diazonium salt with arsenite salts.
Arsonic acids and their derivatives have found some use in agriculture and as pharmaceuticals, though their applications are limited due to the toxicity of arsenic compounds.