Organoarsenic

Organoarsenic compounds are organic molecules that contain at least one covalent bond between carbon and arsenic. They form a diverse class that includes simple aryl- and alkyl-arsines (such as triphenylarsine), dialkyl- and diaryl-arsenicals, arsonic esters, and more complex organoarsenic structures. The chemistry of these compounds is defined by the presence of carbon–arsenic bonds and the ability of arsenic to adopt multiple oxidation states, yielding a wide range of reactivities and applications.

Common subclasses include organoarsines (R3As), arsonates and arsonic esters, and naturally occurring organoarsenicals such as arsenobetaine. Organoarsenicals have long been used in agriculture, medicine, and organic synthesis. Notable examples include roxarsone and arsanilic acid, historically used as poultry feed additives; melarsoprol, an organoarsenical drug for certain parasitic diseases; and triphenylarsine, a laboratory ligand.

Natural occurrence: Arsenic-containing organics occur in marine organisms, notably arsenobetaine and related compounds, which tend to be less toxic than inorganic arsenic. Biotransformation can release inorganic arsenic under certain conditions.

Safety and regulation: The toxicity of organoarsenicals varies widely. While many are less acutely toxic than inorganic arsenic, some can release inorganic arsenic upon metabolism or environmental transformation. Use in agriculture and animal feed has been restricted or banned in various jurisdictions due to concerns about arsenic exposure and environmental contamination. Research continues into their chemistry, biology, and safer applications.