Periodate is an anion composed of iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....

 and 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...

. Periodates include two forms. The metaperiodate ion is IO4; the orthoperiodate ion is IO65−. Usually both forms are called periodates. Periodate is the conjugate base of periodic acid
Periodic acid
Periodic acid, or iodic acid is an oxoacid of iodine having chemical formula HIO4 or H5IO6.In dilute aqueous solution, periodic acid exists as discrete hydronium and metaperiodate ions. When more concentrated, orthoperiodic acid, H5IO6, is formed; this dissociates into hydronium and...


In neutral or weak acid conditions, IO4 is most common, in equilibrium with a smaller amount of H4IO6. In basic conditions, H3IO62− is formed, plus some other ions.

Like its neighbor, tellurium, and unlike lighter halogens, iodine tends to be hexacoordinate
Hexacoordinate in chemistry generally refers to a molecule with six ligands or atomic attachments arranged around a single metal atom in the centre...

, and the units HnIO6(5−n)- are quite common; but tetracoordinate
Tetracoordinate in coordination chemistry generally refers to four ligands or atomic attachments to a single metal centre. Tetracoordinate species can form tetrahedral, square planar or pyramidal geometries. This is usually dictated by lone electron pairs on the metal centre....

 units, such as IO4, are also quite common with iodine, tetracoordinate being the only form possible with lighter perhalogenates, such as perchlorate
Perchlorates are the salts derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders. They are used extensively within the pyrotechnics industry, and ammonium perchlorate is also a...


Sodium metaperiodate can be isolated from the oxidation of sodium iodide
Sodium iodide
Sodium iodide is a white, crystalline salt with chemical formula NaI used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.-Uses:Sodium iodide is commonly used to treat and prevent iodine deficiency....

 with sodium hypochlorite and is best recrystallized from nitric acid
Nitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...

. However, electrochemistry offers an easier alternative.


Periodates can cleave carbon-carbon bonds when both carbon atoms bear an oxygen atom, either in the form of a hydroxyl
A hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...

 or a carbonyl
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....

 group. This property is often utilized in molecular biochemistry for the purposes of modifying saccharide rings, as many five- and six-membered sugars often have vicinal diol
A diol or glycol is a chemical compound containing two hydroxyl groups A geminal diol has two hydroxyl groups bonded to the same atom...

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