Periodic acid is also used as an oxidising agent of moderate strength, as exemplified in the Babler oxidation of secondary allyl alcohols which are oxidised to enones by stoichiometric amounts of orthoperiodic acid with catalyst PCC.

The structure of metaperiodic acid also includes IO 6 octahedra, however these are connected via cis-edge-sharing with bridging oxygens to form one-dimensional infinite chains. Periodate is part of a series of oxyacids in which iodine can assume oxidation states of −1, +1, +3, +5, or +7. This can be useful in determining the structure of carbohydrates as periodic acid can be used to open saccharide rings. This process is often used in labeling saccharides with fluorescent molecules or other tags such as biotin.This is commercially available, but can also be produced by the oxidation of iodates with chlorine and sodium hydroxide. H 3 IO 6 2 − ↽ − − ⇀ H 2 IO 6 3 − + H + {\displaystyle {\ce {H3IO6 Metaperiodic acid can also be prepared from various orthoperiodates by treatment with dilute nitric acid.

Further heating to around 150°C gives iodine pentoxide ( I 2O 5) rather than the expected anhydride diiodine heptoxide ( I 2O 7). F. Holleman; continued by Egon Wiberg; translated by Mary Eagleson, William Brewer; revised by Bernhard J. It is one of a number of oxyanions of iodine and is the highest in the series, with iodine existing in oxidation state +7.It can exist in two forms: orthoperiodic acid, with the chemical formula H 5IO 6, and metaperiodic acid, which has the formula HIO 4. H 5 IO 6 + H + + 2 e − ⟶ IO 3 − + 3 H 2 O {\displaystyle {\ce {H5IO6 + H+ + 2e- -> IO3- + 3 H2O}}} E° = 1. Because the process requires vicinal diols, periodate oxidation is often used to selectively label the 3′-termini of RNA ( ribose has vicinal diols) instead of DNA as deoxyribose does not have vicinal diols. Crystal Structure Determination of Metaperiodic Acid, HIO 4, with Combined X-Ray and Neutron Diffraction". Most notably periodic acid will cleave vicinal diols into two aldehyde or ketone fragments ( Malaprade reaction).