Sodium periodate

Sodium periodate is an inorganic salt, composed of a sodium cation and the periodate anion. It may also be regarded as the sodium salt of periodic acid. Like many periodates it can exist in two different forms: sodium metaperiodate, which has the formula NaIO₄, and sodium orthoperiodate, normally this means sodium hydrogen periodate (Na₂H₃IO₆) but the fully reacted sodium orthoperiodate salt, Na₅IO₆, can also be prepared. Both salts are useful oxidising agents.[1]

Sodium periodate

Names
IUPAC name Sodium periodate
Other names Sodium metaperiodate
Identifiers
CAS Number	7790-28-5^Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:75226^N
ChemSpider	58683^Y
ECHA InfoCard	100.029.270
EC Number	232-197-6
PubChem CID	23667635
RTECS number	SD4550000
UNII	98W4A29X43^Y
CompTox Dashboard (EPA)	DTXSID30894075
InChI InChI=1S/HIO4.Na/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1^Y Key: JQWHASGSAFIOCM-UHFFFAOYSA-M^Y InChI=1/HIO4.Na/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1 Key: JQWHASGSAFIOCM-REWHXWOFAO InChI=1S/HIO4.Na/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1 Key: JQWHASGSAFIOCM-UHFFFAOYSA-M
SMILES [O-]I(=O)(=O)=O.[Na+]
Properties
Chemical formula	NaIO4
Molar mass	213.8918 g/mol
Appearance	white crystals
Density	3.865 g/cm^3 (anhydrous) 3/210 g/cm^3
Melting point	300 °C (572 °F; 573 K) (anhydrous) 175 °C (347 °F; 448 K) (trihydrate) (decomposes)
Solubility in water	soluble
Solubility	soluble in acids
Structure
Crystal structure	tetragonal (anhydrous) trigonal (trihydrate)
Hazards
NFPA 704 (fire diamond)	0 2 0
Related compounds
Other anions	sodium perchlorate, sodium perbromate
Other cations	potassium periodate, periodic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is ^YN ?)
Infobox references

Preparation

Classically, periodate was most commonly produced in the form of sodium hydrogen periodate (Na₃H₂IO₆).[2] This is commercially available, but can also be produced by the oxidation of iodates with chlorine and sodium hydroxide.[3] Or, similarly, from iodides by oxidation with bromine and sodium hydroxide:

NaIO₃ + Cl₂ + 4 NaOH → Na₃H₂IO₆ + 2 NaCl + H₂O

NaI + 4 Br₂ + 10 NaOH → Na₃H₂IO₆ + 8 NaBr + 4 H₂O

Modern industrial scale production involves the electrochemical oxidation of iodates, on a PbO₂ anode, with the following standard electrode potential:

H₅IO₆ + H⁺ + 2 e⁻ → IO⁻
₃ + 3 H₂O      E° = 1.6 V[4]

Sodium metaperiodate can be prepared by the dehydration of sodium hydrogen periodate with nitric acid.[2]

Na₃H₂IO₆ + 2 HNO₃ → NaIO₄ + 2 NaNO₃ + 2 H₂O

Structure

Sodium metaperiodate (NaIO₄) forms tetragonal crystals (space group I4₁/_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.[5]

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.[6]

Powder diffraction indicates that Na₅IO₆ crystallises in the monoclinic system (space group C2/m).[7]

Uses

Further information: Periodate § Reactions

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.

NaIO₄ is used in organic chemistry to cleave diols to produce two aldehydes.[8]

In 2013 the US Army announced that it would replace environmentally harmful chemicals barium nitrate and potassium perchlorate with sodium metaperiodate for use in their tracer ammunition.[9]

See also

• lead tetraacetate - also effective for diol cleavage via the Criegee oxidation

References

1. 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
2. Riley, edited by Georg Brauer ; translated by Scripta Technica, Inc. Translation editor Reed F. (1963). Handbook of preparative inorganic chemistry. Volume 1 (2nd ed.). New York, N.Y.: Academic Press. pp. 323–324. ISBN 012126601X.CS1 maint: extra text: authors list (link)
3. 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.
4. Parsons, Roger (1959). Handbook of electrochemical constants. Butterworths Scientific Publications Ltd. p. 71.
5. Kálmán, A.; Cruickshank, D. W. J. (15 November 1970). "Refinement of the structure of NaIO₄". Acta Crystallographica Section B. 26 (11): 1782–1785. doi:10.1107/S0567740870004880.
6. 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.
7. 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.
8. McMurry, John. Organic chemistry (8th ed., [international ed.] ed.). Singapore: Brooks/Cole Cengage Learning. pp. 285–286. ISBN 9780840054531.
9. "Picatinny to remove tons of toxins from lethal rounds". U.S. Army. Retrieved 31 October 2013.

• See Fatiadi, Synthesis (1974) 229–272 for a review of periodate chemistry.