Sodium selenite

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Sodium selenite
Sodium selenite.jpg
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.030.230 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 233-267-9
KEGG
PubChem CID
RTECS number
  • VS7350000
UNII
UN number 2630
  • InChI=1S/2Na.H2O3Se/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2 Yes check.svgY
    Key: BVTBRVFYZUCAKH-UHFFFAOYSA-L Yes check.svgY
  • InChI=1/2Na.H2O3Se/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2
    Key: BVTBRVFYZUCAKH-NUQVWONBAC
  • [Na+].[Na+].[O-][Se]([O-])=O
Properties
Na2O3Se
Molar mass 172.948 g·mol−1
Appearancecolourless solid
Density 3.1 g/cm3
Melting point decomposes at 710 °C
85 g/100 mL (20 °C)
Solubility insoluble in ethanol
Structure
monoclinic (anhydrous)
Pharmacology
A12CE02 ( WHO )(Oral), B05XA20 ( WHO ) (Parenteral)
Hazards
GHS labelling:
GHS-pictogram-skull.svg GHS-pictogram-exclam.svg GHS-pictogram-pollu.svg
Danger
H300, H317, H331, H411
P261, P264, P270, P271, P272, P273, P280, P301+P310, P302+P352, P304+P340, P311, P321, P330, P333+P313, P363, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
0
0
Safety data sheet (SDS) ICSC 0698
Related compounds
Related compounds
Sodium sulfite
Sodium selenate
Sodium selenide
sodium biselenite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Sodium selenite is the inorganic compound with the formula Na2SeO3. This salt is a colourless solid. The pink coloured pentahydrate Na2SeO3(H2O)5 is the most common water-soluble selenium compound.

Contents

Synthesis and fundamental reactions

Sodium selenite usually is prepared by the reaction of selenium dioxide with sodium hydroxide: [1]

SeO2 + 2 NaOH → Na2SeO3 + H2O

The hydrate converts to the anhydrous salt upon heating to 40 °C.

According to X-ray crystallography, both anhydrous Na2SeO3 and its pentahydrate feature pyramidal SeO32−. The Se-O distances range from 1.67 to 1.72 Å. [2] Oxidation of this anion gives sodium selenate, Na2SeO4. [3]

Applications

Together with the related barium and zinc selenites, sodium selenite is mainly used in the manufacture of colorless glass. The pink color imparted by these selenites cancels out the green color imparted by iron impurities. [4]

Because selenium is an essential element, sodium selenite is an ingredient in dietary supplements such as multi-vitamin/mineral products, but supplements that provide only selenium use L-selenomethionine or a selenium-enriched yeast.

The US Food and Drug Administration approved a selenium supplement to animal diets; the most common form is sodium selenite for pet foods. According to one article, "not much was known about which selenium compounds to approve for use in animal feeds when the decisions were made back in the 1970s .. At the time the regulatory action was taken, only the inorganic selenium salts (sodium selenite and sodium selenate) were available at a cost permitting their use in animal feed.” [5]

Sodium selenite has been proposed as an effective suicide agent. [6]

Safety

Selenium is toxic in high concentrations. As sodium selenite, the chronic toxic dose for human beings was described as about 2.4 to 3 milligrams of selenium per day. [7] In 2000, the US Institute of Medicine set the adult Tolerable upper intake levels (UL) for selenium from all sources - food, drinking water and dietary supplements - at 400 μg/day. [8] The European Food Safety Authority reviewed the same safety question and set its UL at 300 μg/day. [9]

See also

Related Research Articles

<span class="mw-page-title-main">Selenium</span> Chemical element with atomic number 34 (Se)

Selenium is a chemical element; it has the symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elemental state or as pure ore compounds in Earth's crust. Selenium was discovered in 1817 by Jöns Jacob Berzelius, who noted the similarity of the new element to the previously discovered tellurium.

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Fluoride is an inorganic, monatomic anion of fluorine, with the chemical formula F
, whose salts are typically white or colorless. Fluoride salts typically have distinctive bitter tastes, and are odorless. Its salts and minerals are important chemical reagents and industrial chemicals, mainly used in the production of hydrogen fluoride for fluorocarbons. Fluoride is classified as a weak base since it only partially associates in solution, but concentrated fluoride is corrosive and can attack the skin.

<span class="mw-page-title-main">Mineral (nutrient)</span> Chemical element required as an essential nutrient by organisms to perform life functions

In the context of nutrition, a mineral is a chemical element. Some "minerals" are essential for life, but most are not. Minerals are one of the four groups of essential nutrients; the others are vitamins, essential fatty acids, and essential amino acids. The five major minerals in the human body are calcium, phosphorus, potassium, sodium, and magnesium. The remaining elements are called "trace elements". The generally accepted trace elements are iron, chlorine, cobalt, copper, zinc, manganese, molybdenum, iodine, and selenium; there is some evidence that there may be more.

Selenic acid is the inorganic compound with the formula H2SeO4. It is an oxoacid of selenium, and its structure is more accurately described as O2Se(OH)2. It is a colorless compound. Although it has few uses, one of its salts, sodium selenate is used in the production of glass and animal feeds.

<span class="mw-page-title-main">Selenium dioxide</span> Chemical compound

Selenium dioxide is the chemical compound with the formula SeO2. This colorless solid is one of the most frequently encountered compounds of selenium. It is used in making specialized glasses as well as a reagent in organic chemistry.

<span class="mw-page-title-main">Selenite (ion)</span> Anion composed of selenium and oxygen

Selenite refers to the anion with the chemical formula SeO2−3. It is the oxyanion of selenium. It is the selenium analog of the sulfite ion, SO2−3. Thus selenite is pyramidal and selenium is assigned oxidation state +4. Selenite also refers to compounds that contains this ion, for example sodium selenite Na2SeO3 which is a common source of selenite. Selenite also refers to the esters of selenous acid, for example dimethyl selenite (CH3)2SeO3.

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<span class="mw-page-title-main">Selenium compounds</span> Chemical compounds containing selenium

Selenium compounds are compounds containing the element selenium (Se). Among these compounds, selenium has various oxidation states, the most common ones being −2, +4, and +6. Selenium compounds exist in nature in the form of various minerals, such as clausthalite, guanajuatite, tiemannite, crookesite etc., and can also coexist with sulfide minerals such as pyrite and chalcopyrite. For many mammals, selenium compounds are essential. For example, selenomethionine and selenocysteine are selenium-containing amino acids present in the human body. Selenomethionine participates in the synthesis of selenoproteins. The reduction potential and pKa (5.47) of selenocysteine are lower than those of cysteine, making some proteins have antioxidant activity. Selenium compounds have important applications in semiconductors, glass and ceramic industries, medicine, metallurgy and other fields.

<span class="mw-page-title-main">Sodium selenate</span> Chemical compound

Sodium selenate is the inorganic compound with the formula Na
2
SeO
4
. It exists as the anhydrous salt, the heptahydrate, and the decahydrate. These are white, water-soluble solids. The decahydrate is a common ingredient in multivitamins and livestock feed as a source of selenium. The anhydrous salt is used in the production of some glass. Although the selenates are much more toxic, many physical properties of sodium selenate and sodium sulfate are similar.

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<span class="mw-page-title-main">Iodine in biology</span> Use of Iodine by organisms

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Selenium yeast is a feed additive for livestock, used to increase the selenium content in their fodder. It is a form of selenium currently approved for human consumption in the EU and Britain. Inorganic forms of selenium are used in feeds. Since these products can be patented, producers can demand premium prices. It is produced by fermenting Saccharomyces cerevisiae in a selenium-rich media.

<span class="mw-page-title-main">Selenium in biology</span> Use of Selenium by organisms

Selenium is an essential micronutrient for animals, though it is toxic in large doses. In plants, it sometimes occurs in toxic amounts as forage, e.g. locoweed. Selenium is a component of the amino acids selenocysteine and selenomethionine. In humans, selenium is a trace element nutrient that functions as cofactor for glutathione peroxidases and certain forms of thioredoxin reductase. Selenium-containing proteins are produced from inorganic selenium via the intermediacy of selenophosphate (PSeO33−).

<span class="mw-page-title-main">Thorium(IV) nitrate</span> Chemical compound

Thorium(IV) nitrate is a chemical compound, a salt of thorium and nitric acid with the formula Th(NO3)4. A white solid in its anhydrous form, it can form tetra- and pentahydrates. As a salt of thorium it is weakly radioactive.

Iron(II) selenate (ferrous selenate) is an inorganic compound with the formula FeSeO4. It has anhydrous and several hydrate forms. The pentahydrate has the structure, [Fe(H2O)4]SeO4•H2O, isomorphous to the corresponding iron(II) sulfate. Heptahydrate is also known, in form of unstable green crystalline solid.

A selenate selenite is a chemical compound or salt that contains selenite and selenate anions (SeO32- and SeO42-). These are mixed anion compounds. Some have third anions.

<span class="mw-page-title-main">Iron(III) selenite</span> Chemical compound

Iron(III) selenite is an inorganic compound with the chemical formula Fe2(SeO3)3. It exists anhydrous form and as various hydrates. The heptahydrate is produced by the reaction of ferric chloride and selenous acid (or sodium selenite) at a pH of 1.05. The pentahydrate has the structure of Fe2(OH)3(H2O)2(HSeO3)3. The single crystal diffraction of the trihydrate shows that its structure consists of two independent FeO6 octahedrons and SeO32− with a tetrahedral geometry.

References

  1. F. Féher, "Sodium Selenite" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 432.
  2. Wickleder MS (2002). "Sodium Selenite, Na2SeO3". Acta Crystallographica Section E. 58 (11): i103–i104. Bibcode:2002AcCrE..58I.103W. doi:10.1107/S1600536802019384. ISSN   1600-5368.
  3. Mereiter K (2013). "Sodium Selenite Pentahydrate, Na2SeO3·5H2O". Acta Crystallographica Section E. 69 (11): i77–i78. doi:10.1107/S1600536813028602. PMC   3884237 . PMID   24454013.
  4. Bernd E. Langner "Selenium and Selenium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry (published on-line in 2000) Wiley-VCH, Weinheim, 2002 doi : 10.1002/14356007.a23_525
  5. Schrauzer GN (2001). "Nutritional selenium supplements: product types, quality, and safety". Journal of the American College of Nutrition. 20 (1): 1–4. doi:10.1080/07315724.2001.10719007. PMID   11293463. S2CID   12668227.
  6. Nitschke, Philip (28 February 2016). The peaceful pill ehandbook. Stewart, Fiona, 1966- (January 2021 ed.). Bellingham, WA. p. 192. ISBN   978-0-9758339-1-9. OCLC   1003529499.{{cite book}}: CS1 maint: location missing publisher (link)
  7. Wilber CG (1980). "Toxicology of selenium". Clinical Toxicology. 17 (2): 171–230. doi:10.3109/15563658008985076. PMID   6998645.
  8. Institute of Medicine (2000). "Selenium". Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: The National Academies Press. pp. 284–324. doi:10.17226/9810. ISBN   978-0-309-06935-9. PMID   25077263.
  9. Tolerable Upper Intake Levels For Vitamins And Minerals (PDF), European Food Safety Authority, 2006