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Thiocyanic acid






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From Wikipedia, the free encyclopedia
  

Thiocyanic acid[1]
Skeletal formula of thiocyanic acid with the explicit hydrogen added
Spacefill model of thiocyanic acid
  Carbon, C
  Sulfur, S
  Nitrogen, N
  Hydrogen, H
Names
IUPAC name

Thiocyanic acid[4]

Other names
  • Hydrogen thiocyanate[2]
  • Sulfocyanic acid[3]
    • Identifiers

    CAS Number

    3D model (JSmol)
  • isothiocyanic acid: Interactive image
    • 3DMet
    ChEBI
    ChEMBL
    ChemSpider
    ECHA InfoCard 100.006.672 Edit this at Wikidata
    EC Number
    • 207-337-4

    Gmelin Reference

    		 25178
    KEGG
    MeSH thiocyanic+acid

    PubChem CID
    UNII

    CompTox Dashboard (EPA)

    • InChI=1S/CHNS/c2-1-3/h3H checkY

      Key: ZMZDMBWJUHKJPS-UHFFFAOYSA-N checkY

    • thiocyanic acid: SC#N

    • isothiocyanic acid: N=C=S

    Properties

    Chemical formula

    		 HSCN
    Molar mass 59.09 g·mol−1
    Appearance
    • Colourless liquid[5]
  • Colourless gas, autopolymerizing to white solid[2]
    • Odor Pungent
    Density 2.04 g/cm3
    Melting point
    • 5 °C (oligomers?)[5]
  • -110 °C (monomer?)[6]

    • Solubility in water

    		 Miscible
    Solubility Soluble in ethanol, diethyl ether
    log P 0.429
    Vapor pressure 4.73 mmHg (631 Pa)[7]
    Acidity (pKa) 0.926
    Basicity (pKb) 13.071
    Hazards
    GHS labelling:

    Pictograms

    		 GHS07: Exclamation mark

    Signal word

    		 Warning

    Hazard statements

    		 H302, H312, H332, H412

    Precautionary statements

    		 P261, P264, P270, P271, P273, P280, P301+P312, P302+P352, P304+P312, P304+P340, P312, P322, P330, P363, P501
    Related compounds

    Related compounds
  • Potassium selenocyanate
  • Hydrogen cyanide
  • Cyanogen iodide
  • Cyanogen bromide
  • Cyanogen chloride
  • Cyanogen fluoride
  • Acetonitrile
  • Aminoacetonitrile
  • Glycolonitrile
  • Cyanogen

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

    ☒N verify (what is checkY☒N ?)

    Infobox references

    Thiocyanic acid is a chemical compound with the formula HSCN and structure H−S−C≡N, which exists as a tautomer with isothiocyanic acid (H−N=C=S).[8] The isothiocyanic acid tautomer tends to dominate with the compound being about 95% isothiocyanic acid in the vapor phase.[9]

    Tautomerism between thiocyanic acid (left) and isothiocyanic acid (right)

    It is a moderately strong acid,[10] with a pKa of 1.1 at 20 °C and extrapolated to zero ionic strength.[11]

    One of the thiocyanic acid tautomers, HSCN, is predicted to have a triple bond between carbon and nitrogen. Thiocyanic acid has been observed spectroscopically.[12]

    The salts and esters of thiocyanic acid are known as thiocyanates. The salts are composed of the thiocyanate ion ([SCN]−) and a suitable cation (e.g., potassium thiocyanate, KSCN). The esters of thiocyanic acid have the general structure R−S−C≡N, where R stands for an organyl group.

    Isothiocyanic acid, HNCS, is a Lewis acid whose free energy, enthalpy and entropy changes for its 1:1 association with a variety of Lewis bases in carbon tetrachloride solution at 25 °C have been reported.[13]< HNCS acceptor properties are discussed in the ECW model. The salts are composed of the thiocyanate ion ([SCN]−) and a suitable cation (e.g., ammonium thiocyanate, [NH4]+[SCN]−). Isothiocyanic acid forms isothiocyanates R−N=C=S, where R stands for an organyl group.

    Wikimedia Commons has media related to Thiocyanic acid.

    References[edit]

    1. ^ Merck Index, 11th Edition, 9257.
  • ^ a b "Thiocyanic acid". The Merck Index. Royal Society of Chemistry.
  • ^ von Richter, Victor (1922). Organic Chemistry or Chemistry of the Carbon Compounds. Vol. 1. Translated by Spielmann, Percy E. Philadelphia: P. Blakiston's Son & Co. p. 466.
  • ^ "Thiocyanic acid" entry in PubChem (database).
  • ^ a b ILO and WHO staff. "Thiocyanic acid" safety card. European Commission
  • ^ Birckenbach, Lothar (1942). Forschungen und Fortschritte. 18: 232–3 {{cite journal}}: Missing or empty |title= (help). As citedinCAS Common Chemistry.
  • ^ Brown, Jay A. (ed.; 2024), "Thiocyanic Acid" in Haz-Map (database). Engineered IT.
  • ^ Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 0-12-352651-5.
  • ^ Beard, C. I.; Dailey, B. P. (1950). "The Structure and Dipole Moment of Isothiocyanic Acid" (PDF). The Journal of Chemical Physics. 18 (11): 1437. Bibcode:1950JChPh..18.1437B. doi:10.1063/1.1747507. hdl:1721.1/4934.
  • ^ Munegumi, Toratane (23 January 2013). "Where is the Border Line between Strong Acids and Weak Acids?". World Journal of Chemical Education. 1 (1): 12–16.
  • ^ Martell, A. E.; Smith, R. M.; Motelaitis, R. J. (2001). NIST Database 46. Gaithersburg, MD: National Institute of Standards and Technology.
  • ^ Wierzejewska, M.; Mielke, Z. (2001). "Photolysis of Isothiocyanic Acid HNCS in Low-Temperature Matrices. Infrared Detection of HSCN and HSNC Isomers". Chemical Physics Letters. 349 (3–4): 227–234. Bibcode:2001CPL...349..227W. doi:10.1016/S0009-2614(01)01180-0.
  • ^ Barakat, T. M.; Nelson, Jane; Nelson, S. M.; Pullin, A. D. E. (1969). "Spectra and hydrogen-bonding of characteristics of thiocyanic acid. Part 4.—Association with weak proton acceptors". Trans. Faraday Soc. 65: 41–51. doi:10.1039/tf9696500041. ISSN 0014-7672.

    • Retrieved from "https://en.wikipedia.org/w/index.php?title=Thiocyanic_acid&oldid=1227518739"
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