Sodium periodate is an inorganic salt, composed of a sodiumcation and the periodateanion. It may also be regarded as the sodium salt of periodic acid. Like many periodates, it can exist in two different forms: sodium metaperiodate (formula NaIO4) and sodium orthoperiodate (normally Na2H3IO6, but sometimes the fully reacted salt Na5IO6). Both salts are useful oxidising agents.[2]
Preparation
Classically, periodate was produced in the form of sodium hydrogen periodate (Na3H2IO6).[3] This commercially available, but can also be produced by the oxidation of iodates with chlorine and sodium hydroxide.[3][4] Or, similarly, from iodides by oxidation with bromine and sodium hydroxide:
Sodium metaperiodate can be prepared by the dehydration of sodium hydrogen periodate with nitric acid.
Na3H2IO6 + 2 HNO3 → NaIO4 + 2 NaNO3 + 2 H2O
Structure
Sodium metaperiodate (NaIO4) forms tetragonal crystals (space groupI41/a) consisting of slightly distorted IO− 4 ions with average I–O bond distances of 1.775 Å; the Na+ ions are surrounded by 8 oxygen atoms at distances of 2.54 and 2.60 Å.[6]
Sodium hydrogen periodate (Na2H3IO6) forms orthorhombic crystals (space group Pnnm). Iodine and sodium atoms are both surrounded by an octahedral arrangement of 6 oxygen atoms; however the NaO6 octahedron is strongly distorted. IO6 and NaO6 groups are linked via common vertices and edges.[7]
Sodium periodate can be used in solution to open saccharide rings between vicinal diols leaving two aldehyde groups. This process is often used in labeling saccharides with fluorescent molecules or other tags such as biotin. Because the process requires vicinal diols, periodate oxidation is often used to selectively label the 3′-ends of RNA (ribose has vicinal diols) instead of DNA as deoxyribose does not have vicinal diols.
^Andrew G. Wee, Jason Slobodian, Manuel A. Fernández-Rodríguez and Enrique Aguilar "Sodium Periodate" e-EROS Encyclopedia of Reagents for Organic Synthesis 2006. doi:10.1002/047084289X.rs095.pub2
^ abM. Schmeisser (1963). "Periodic acid". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2pages=323. NY,NY: Academic Press.
^Hill, Arthur E. (October 1928). "Ternary Systems. VII. The Periodates of the Alkali Metals". Journal of the American Chemical Society. 50 (10): 2678–2692. doi:10.1021/ja01397a013.
^Jansen, Martin; Rehr, Anette (1988). "Na2H3IO6, eine Variante der Markasitstruktur". Zeitschrift für anorganische und allgemeine Chemie (in German). 567 (1): 95–100. doi:10.1002/zaac.19885670111.
^Betz, T.; Hoppe, R. (May 1984). "Über Perrhenate. 2. Zur Kenntnis von Li5ReO6 und Na5ReO6 – mit einer Bemerkung über Na5IO6". Zeitschrift für anorganische und allgemeine Chemie (in German). 512 (5): 19–33. doi:10.1002/zaac.19845120504.