Sodium periodate is an
inorganic
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
salt, composed of a
sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
cation
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
and the
periodate
Periodate is an anion composed of iodine and oxygen. It is one of a number of oxyanions of iodine and is the highest in the series, with iodine existing in oxidation state +7. Unlike other perhalogenates, such as perchlorate, it can exist in two ...
anion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
. It may also be regarded as the sodium
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
of
periodic acid
Periodic acid ( ) is the highest oxoacid of iodine, in which the iodine exists in oxidation state +7. Like all periodates it can exist in two forms: orthoperiodic acid, with the chemical formula , and metaperiodic acid, which has the formula .
...
. Like many periodates, it can exist in two different forms: sodium ''meta''periodate (formula NaIO
4) and sodium ''ortho''periodate (normally Na
2H
3IO
6, but sometimes the fully reacted salt Na
5IO
6). Both salts are useful oxidising agents.
Preparation
Classically, periodate was most commonly produced in the form of sodium hydrogen periodate ().
This is commercially available, but can also be produced by the oxidation of
iodate
An iodate is the polyatomic anion with the formula . It is the most common form of iodine in nature, as it comprises the major iodine-containing ores. Iodate salts are often colorless. They are the salts of iodic acid.
Structure
Iodate is pyram ...
s with
chlorine
Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
and
sodium hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and alkali ...
. Or, similarly, from
iodide
An iodide ion is the ion I−. Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine defic ...
s by oxidation with
bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simila ...
and sodium hydroxide:
:
\overset + Cl2 + 4 NaOH -> Na3H2IO6 + 2NaCl + H2O
:
NaI + 4 Br2 + 10 NaOH -> Na3H2IO6 + 8 NaBr + 4 H2O
Modern industrial scale production involves the
electrochemical
Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outco ...
oxidation of iodates, on a
lead dioxide
Lead(IV) oxide is the inorganic compound with the formula PbO2. It is an oxide where lead is in an oxidation state of +4. It is a dark-brown solid which is insoluble in water. It exists in two crystalline forms. It has several important applicatio ...
() anode, with the following
standard electrode potential
In electrochemistry, standard electrode potential E^\ominus, or E^\ominus_, is a measure of the reducing power of any element or compound. The IUPAC "Gold Book" defines it as: ''"the value of the standard emf (electromotive force) of a cell in wh ...
:
:
H5IO6 + H+ + 2e- -> IO3- + 3 H2O
Sodium metaperiodate can be prepared by the dehydration of sodium hydrogen periodate with
nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
.
:
Na3H2IO6 + 2 HNO3 -> NaIO4 + 2 NaNO3 + 2 H2O
Structure
Sodium metaperiodate (NaIO
4) forms
tetragonal
In crystallography, the tetragonal crystal system is one of the 7 crystal systems. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a square ...
crystals (
space group
In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchan ...
''I''4
1/
a) consisting of slightly distorted 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.
Sodium hydrogen periodate (Na
2H
3IO
6) forms
orthorhombic crystals (space group Pnnm). Iodine and sodium atoms are both surrounded by an octahedral arrangement of 6 oxygen atoms; however the NaO
6 octahedron is strongly distorted. IO
6 and NaO
6 groups are linked via common vertices and edges.
Powder diffraction
Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials. An instrument dedicated to performing such powder measurements is call ...
indicates that Na
5IO
6 crystallises in the
monoclinic
In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...
system (space group C2/m).
Uses
Sodium periodate can be used in solution to open saccharide rings between
vicinal diols
Vicinal may refer to:
* Vicinal (chemistry)
In chemistry the descriptor vicinal (from Latin ''vicinus'' = neighbor), abbreviated ''vic'', describes any two functional groups bonded to two adjacent carbon atoms (i.e., in a 1,2-relationship).
R ...
leaving two aldehyde groups. This process is often used in labeling saccharides with fluorescent molecules or other tags such as
biotin
Biotin (or vitamin B7) is one of the B vitamins. It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. The name ''biotin'', bor ...
. Because the process requires vicinal diols, periodate oxidation is often used to selectively label the 3′-ends of
RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
(
ribose
Ribose is a simple sugar and carbohydrate with molecular formula C5H10O5 and the linear-form composition H−(C=O)−(CHOH)4−H. The naturally-occurring form, , is a component of the ribonucleotides from which RNA is built, and so this compo ...
has vicinal diols) instead of
DNA as
deoxyribose
Deoxyribose, or more precisely 2-deoxyribose, is a monosaccharide with idealized formula H−(C=O)−(CH2)−(CHOH)3−H. Its name indicates that it is a deoxy sugar, meaning that it is derived from the sugar ribose by loss of a hydroxy group. D ...
does not have vicinal diols.
NaIO
4 is used in
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...
to cleave
diol
A diol is a chemical compound containing two hydroxyl groups ( groups). An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified.
The most common industrial diol is e ...
s to produce two
aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
s.
In 2013 the
US Army
The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...
announced that it would replace environmentally harmful chemicals
barium nitrate
Barium nitrate is the inorganic compound with the chemical formula Ba( NO3)2. It, like most barium salts, is colorless, toxic, and water-soluble. It burns with a green flame and is an oxidizer; the compound is commonly used in pyrotechnics.
Man ...
and
potassium perchlorate with sodium metaperiodate for use in their
tracer ammunition
Tracer ammunition (AMO) (Tracers) are bullets or cannon-caliber projectiles that are built with a small pyrotechnic charge in their base. When fired, the pyrotechnic composition is ignited by the burning powder and burns very brightly, making ...
.
See also
*
lead tetraacetate
Lead(IV) acetate or lead tetraacetate is an organometallic compound with chemical formula . It is a colorless solid that is soluble in nonpolar, organic solvents, indicating that it is not a salt. It is degraded by moisture and is typically store ...
- also effective for diol cleavage via the
Criegee oxidation
The Criegee oxidation is a glycol cleavage reaction in which vicinal diols are oxidized to form ketones and aldehydes using lead tetraacetate. It is analogous to the Malaprade reaction, but uses a milder oxidant. This oxidation was discovere ...
References
*See Fatiadi, ''Synthesis'' (1974) 229–272 for a review of periodate chemistry.
{{DEFAULTSORT:Sodium Periodate
Periodates
Sodium compounds
Oxidizing agents