This can be useful in determining the structure of carbohydrates as periodic acid can be used to open saccharide rings. Metaperiodic acid can also be prepared from various orthoperiodates by treatment with dilute nitric acid.

H 3 IO 6 2 − ↽ − − ⇀ H 2 IO 6 3 − + H + {\displaystyle {\ce {H3IO6 H 5 IO 6 + H + + 2 e − ⟶ IO 3 − + 3 H 2 O {\displaystyle {\ce {H5IO6 + H+ + 2e- -> IO3- + 3 H2O}}} E° = 1. It can exist in two forms: orthoperiodic acid, with the chemical formula H 5IO 6, and metaperiodic acid, which has the formula HIO 4.

Orthoperiodic acid can be dehydrated to give metaperiodic acid by heating to 100°C under reduced pressure. F. Holleman; continued by Egon Wiberg; translated by Mary Eagleson, William Brewer; revised by Bernhard J. For example, sodium metaperiodate, NaIO 4, can be synthesised from HIO 4 while sodium orthoperiodate, Na 5IO 6 can be synthesised from H 5IO 6. This is commercially available, but can also be produced by the oxidation of iodates with chlorine and sodium hydroxide. It is one of a number of oxyanions of iodine and is the highest in the series, with iodine existing in oxidation state +7.

Crystal Structure Determination of Metaperiodic Acid, HIO 4, with Combined X-Ray and Neutron Diffraction". This process is often used in labeling saccharides with fluorescent molecules or other tags such as biotin.Periodate is part of a series of oxyacids in which iodine can assume oxidation states of −1, +1, +3, +5, or +7.

Expanding the scope of the Babler–Dauben oxidation: 1,3-oxidative transposition of secondary allylic alcohols". 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. 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. It can combine with a number of counter ions to form periodates, which may also be regarded as the salts of periodic acid.Most notably periodic acid will cleave vicinal diols into two aldehyde or ketone fragments ( Malaprade reaction). Periodic acid ( / ˌ p ɜːr aɪ ˈ ɒ d ɪ k/ per-eye- OD-ik) is the highest oxoacid of iodine, in which the iodine exists in oxidation state +7. Orthoperiodic acid forms monoclinic crystals ( space group P2 1/ n) consisting of a slightly deformed IO 6 octahedron interlinked via bridging hydrogens. Further heating to around 150°C gives iodine pentoxide ( I 2O 5) rather than the expected anhydride diiodine heptoxide ( I 2O 7). 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.