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 (formula‍ NaIO₄) and sodium orthoperiodate (normally Na₂H₃IO₆, but sometimes the fully reacted salt Na₅IO₆). Both salts are useful oxidising agents.^[2]

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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/cm3 (anhydrous) 3/210 g/cm3
Melting point	300 °C (572 °F; 573 K) (anhydrous) 175 °C (347 °F; 448 K) (trihydrate) (decomposes)
Solubility in water	91 g/L[1]
Solubility	soluble in acids
Structure
Crystal structure	tetragonal (anhydrous) trigonal (trihydrate)
Hazards
NFPA 704 (fire diamond)	2 0 3 OX
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

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Classically, periodate was most commonly produced in the form of sodium hydrogen periodate (Na₃H₂IO₆).^[3] This is commercially available, but can also be produced by the oxidation of iodates with chlorine and sodium hydroxide.^[4] Or, similarly, from iodides by oxidation with bromine and sodium hydroxide:

${\displaystyle {\ce {{\overset {sodium\ iodate}{NaIO3}}+Cl2{}+4NaOH->Na3H2IO6{}+2NaCl{}+H2O}}}$

${\displaystyle {\ce {NaI + 4 Br2 + 10 NaOH -> Na3H2IO6 + 8 NaBr + 4 H2O}}}$

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

${\displaystyle {\ce {H5IO6 + H+ + 2e- -> IO3- + 3 H2O}}}$     E° = 1.6 V^[5]

Sodium metaperiodate can be prepared by the dehydration of sodium hydrogen periodate with nitric acid.^[3]

${\displaystyle {\ce {Na3H2IO6 + 2 HNO3 -> NaIO4 + 2 NaNO3 + 2 H2O}}}$

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.^[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]

Powder diffraction indicates that Na₅IO₆ crystallises in the monoclinic system (space group C2/m).^[8]

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.^[9]

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.^[10]

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