What is "phosphite"

Phosphite \Phos"phite\, n. (Chem.) A salt of phosphorous acid.

n. 1 (context chemistry English) any salt or ester of phosphorous acid 2 (context chemistry English) the anion PO₃^3-, or the trivalent radical PO₃

A phosphite in inorganic chemistry is a salt of phosphorous acid, HPO and following the IUPAC naming recommendations the phosphite ion would be , a salt of P(OH).

Historically phosphite has referred to salts containing and this is because aqueous HPO is not triprotic P(OH) but almost exclusively the diprotic HP(O)(OH) (IUPAC recommended name of phosphonic acid). The IUPAC-recommended name for the ion is phosphonate and this naming convention is becoming more common. In the US the IUPAC naming conventions for inorganic compounds are taught at high school, but not as a 'required' part of the curriculum. A well-known university-level textbook follows the IUPAC recommendations. In practise any reference to "phosphite" should be investigated carefully to determine which naming convention is being employed.

The term phosphite is also used to mean phosphite ester, an organophosphorus compound with the formula P(OR).