Iodites

As iodite are salts of Iodigen acid referred to which the iodite anion IO ₂ ^- contained. Iodine is in the +3 oxidation state. Iodites are only known as reactive intermediates in aqueous solution and so far could not be isolated as pure substances in solid form.

Classification

Iodites belong to the substance group of salts of halogenated oxygen acids and thereby to the subgroup of salts of iodinated acids (with anions of the formula type IO _n ^- with n = 1, 2, 3, 4; with periodates further variants) or to the subgroup of halogenites (salts of halogenates Acids with anions of the formula type XO ₂ ^- with X = Cl, Br, I, At).

Occur

Iodite IO ₂ ^- is formed as an intermediate in aqueous solution during the disproportionation of Hypoiodit IO ^- in iodide I ^- and iodate IO ₃ ^-, which takes place in two steps :

1) Disproportionation of hypoiodite to iodide and iodite:

${\displaystyle \mathrm {{\overset {+1}{\ I}}\!O^{-}+{\overset {+1}{\ I}}\!O^{-}\ \longrightarrow \ {\overset {-1}{I}}\!{}^{-}+{\overset {+3}{\ I}}\!O_{2}^{-}} }$

2) Hypoiodite oxidizes iodite to iodate and is itself reduced to iodide :

${\displaystyle \mathrm {{\overset {+1}{\ I}}\!O^{-}+{\overset {+3}{\ I}}\!O_{2}^{-}\ \longrightarrow \ {\overset {-1}{I}}\!{}^{-}+{\overset {+5}{\ I}}\!O_{3}^{-}} }$

3) overall reaction:

${\displaystyle \mathrm {3\;{\overset {+1}{\ I}}\!O^{-}\ \longrightarrow \ 2\;{\overset {-1}{I}}\!{}^{-}+{\overset {+5}{\ I}}\!O_{3}^{-}} }$

Salts of inorganic acids containing iodine

Oxidation level of iodine	−1	+1	+3	+5	+7
Surname	Iodides	Hypoiodite	Iodites	Iodates	Periodates
Formula of the anion	I -	IO -	IO 2 -	IO 3 -	IO 4 - , IO 6 5− and others

Individual evidence

1. ^ ^{A b} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. De Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 463–465, 474–475 ( limited preview of the 101st edition in Google Book Search).