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Contents

   



(Top)
 


1 Formation and properties  





2 Uses  



2.1  Medical  







3 Health effects  





4 References  





5 External links  














Selenous acid






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From Wikipedia, the free encyclopedia
 


Selenous acid[1]
Structural formula
Ball-and-stick model
Selenous acid on a watchglass
Names
IUPAC names

Selenous acid
Selenic(IV) acid

Other names

Selenious acid

Identifiers

CAS Number

3D model (JSmol)

ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.029.067 Edit this at Wikidata
EC Number
  • 231-974-7
KEGG

PubChem CID

RTECS number
  • VS7175000
UNII
UN number 3283 2630

CompTox Dashboard (EPA)

  • InChI=1S/H2O3Se/c1-4(2)3/h(H2,1,2,3) checkY

    Key: MCAHWIHFGHIESP-UHFFFAOYSA-N checkY

  • InChI=1/H2O3Se/c1-4(2)3/h(H2,1,2,3)

    Key: MCAHWIHFGHIESP-UHFFFAOYAW

  • O[Se+]([O-])O

Properties

Chemical formula

H2SeO3
Molar mass 128.984 g·mol−1
Appearance white hygroscopic crystals
Density 3.0 g/cm3
Melting point decomposes at 70 °C

Solubility in water

very soluble
Solubility soluble in ethanol
Acidity (pKa) pKa1 = 2.46
pKa2 = 7.3[2]
Conjugate base Hydrogenselenite

Magnetic susceptibility (χ)

−45.4·10−6cm3/mol
Pharmacology

Routes of
administration

Intravenous infusion
Legal status
Hazards
GHS labelling:

Pictograms

GHS06: ToxicGHS08: Health hazardGHS09: Environmental hazard

Signal word

Danger

Hazard statements

H301, H331, H373, H410

Precautionary statements

P260, P261, P264, P270, P271, P273, P301+P310, P304+P340, P311, P314, P321, P330, P391, P403+P233, P405, P501
Related compounds

Other anions

Selenic acid
Hydrogen selenide

Other cations

Sodium selenite

Related compounds

  • Tellurous acid
  • Polonous acid
  • Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

    checkY verify (what is checkY☒N ?)

    Infobox references

    Selenious Acid
    Clinical data
    AHFS/Drugs.comMonograph
    License data
    Identifiers
    DrugBank
    CompTox Dashboard (EPA)
    ECHA InfoCard100.029.067 Edit this at Wikidata

    Selenous acid (orselenious acid) is the chemical compound with the formula H2SeO3. Structurally, it is more accurately described by O=Se(OH)2. It is the principal oxoacidofselenium; the other being selenic acid.

    Formation and properties

    [edit]

    Selenous acid is analogous to sulfurous acid, but it is more readily isolated. Selenous acid is easily formed upon the addition of selenium dioxide to water. As a crystalline solid, the compound can be seen as pyramidal molecules that are interconnected with hydrogen bonds. In solution it is a diprotic acid:[3]

    H2SeO3 ⇌ H+ + HSeO3  (pKa = 2.62)
    HSeO3 ⇌ H+ + SeO2−3  (pKa = 8.32)

    It is moderately oxidizing in nature, but kinetically slow. In 1 MH+:

    H2SeO3 + 4 H+ + 4 e ⇌ Se + 3 H2O  (Eo = +0.74 V)

    In 1 MOH:

    SeO2−3 + 4 e + 3 H2O ⇌ Se + 6 OH  (Eo = −0.37 V)

    Selenous acid is hygroscopic.[4][5]

    Uses

    [edit]

    The major use is in protecting and changing the color of steel, especially steel parts on firearms.[6] The so-called cold-bluing process uses selenous acid, copper(II) nitrate, and nitric acid to change the color of the steel from silver-grey to blue-grey or black. Alternative procedures use copper sulfate and phosphoric acid instead. This process deposits a coating of copper selenide and is fundamentally different from other bluing processes which generate black iron oxide. Some older razor blades were also made of blued steel.[6]

    Another use for selenious acid is the chemical darkening and patination of copper, brass and bronze, producing a rich dark brown color that can be further enhanced with mechanical abrasion.[citation needed]

    It is used in organic synthesis as an oxidizing agent for the synthesis of 1,2-dicarbonyl compounds, e.g. in laboratory preparation of glyoxal (ethane-1,2-dione) from acetaldehyde.[7]

    Selenious acid is a key component of the Mecke reagent used for drug checking.[8][9]

    Medical

    [edit]

    Selenous acid can supply the trace element indicated in people as a source of selenium.[10][11]

    Health effects

    [edit]

    Like many selenium compounds, selenous acid is highly toxic in excessive quantities, and ingestion of any significant quantity of selenous acid is usually fatal, however it is an approved dietary source in proper amounts. Symptoms of selenium poisoning can occur several hours after exposure, and may include stupor, nausea, severe hypotension and death.

    References

    [edit]
    1. ^ Lide DR (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, Florida: CRC Press. pp. 4–81. ISBN 0-8493-0594-2.
  • ^ Ka and pKa for Polyprotic Acids. ucdsb.on.ca
  • ^ Holleman AF, Wiberg E (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 0-12-352651-5.
  • ^ Lide DR, ed. (1995). CRC Handbook of Chemistry and Physics (76th ed.). Boca Raton, FL: CRC Press Inc. pp. 4–82.
  • ^ "Selenious acid". PubChem. Retrieved 2020-01-17.
  • ^ a b Scarlato EA, Higa J (28 June 1990). "SELENIUM (PIM483)". Retrieved 29 December 2010.
  • ^ "Glyoxal Bisulfite", Organic Syntheses, Collected Volume 3, p.438 (1955).
  • ^ "Colour Test Reagents-Kits for Preliminary Identification of Drugs of Abuse" (PDF). National Institute of Justice. 2000-07-01. Retrieved 2012-01-26.
  • ^ "Material Safety Data Sheet - Product Name: Reagent for Special Opiates" (PDF). Sirchie Finger Print Laboratories, Inc. May 12, 2006. Archived from the original (PDF) on October 18, 2006.
  • ^ "Selenious acid injection, solution". DailyMed. 1 May 2020. Retrieved 22 October 2020.
  • ^ "Drug Approval Package: Selenious Acid Injection". U.S. Food and Drug Administration (FDA). Retrieved 22 October 2020.
  • [edit]
    Retrieved from "https://en.wikipedia.org/w/index.php?title=Selenous_acid&oldid=1189652377"

    Categories: 
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    This page was last edited on 13 December 2023, at 04:55 (UTC).

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