Potassium cyanate

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Potassium cyanate
KNCO.png
Identifiers
CAS number 590-28-3 YesY
PubChem 11378442
ChemSpider 11053 YesY
EC number 209-676-3
KEGG C19067 N
ChEBI CHEBI:38904 YesY
RTECS number GS6825000
Jmol-3D images Image 1
Properties
Molecular formula KOCN
Molar mass 81.1151 g/mol
Appearance white, crystalline powder
Density 2.056 g/cm3
Melting point 315 °C
Boiling point ~ 700°C, decomp.
Solubility in water 75 g/100 mL
Solubility very slightly soluble in alcohol
Structure
Crystal structure tetragonal
Hazards
R-phrases R22
S-phrases S24, S25
LD50 841 mg/kg (oral, rat)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Potassium cyanate is an inorganic compound with the formula KOCN (sometimes denoted KCNO[1]). It is a colourless solid. It is used to prepare many other compounds including useful herbicide. Worldwide production of the potassium and sodium salts was 20,000 tons in 2006.[2]

Structure and bonding[edit]

Cyanate is isoelectronic with carbon dioxide and with azide, being linear. The C-N distance is 121 pm, about 5 pm longer than for cyanide.[3][4] Potassium cyanate is isostructural with potassium azide.[5]

Uses[edit]

For most applications, the potassium and sodium salts can be used interchangeably. Potassium cyanate is often preferred to the sodium salt, which is less soluble in water and less readily available in pure form.

Potassium cyanate is used as a basic raw material for various organic syntheses, including, urea derivatives, semicarbazides, carbamates and isocyanates. For example, it is used to prepare the drug hydroxyurea. It is also used for the heat treatment of metals (e.g., Ferritic nitrocarburizing).[2][6]

Therapeutic Uses[edit]

Potassium Cyanate has been used to reduce the percentage of sickled erythrocytes under certain conditions and has also increased the number of deformalities. In an aqueous solution, it has prevented irreversibly the in vitro sickling of hemoglobins containing human erythrocytes during deoxygenization. Veterinarians have also found potassium cyanate useful in that the cyanate salts and isocyanates can treat parasite diseases in both birds and mammals.[7]

Preparation and reactions[edit]

KOCN is prepared by heating urea with potassium carbonate at 400 °C:

2 OC(NH2)2 + K2CO3 → 2 KOCN + (NH4)2CO3

The reaction produces a liquid. Intermediates and impurities include biuret, cyanuric acid, and potassium allophanate (KO2CNHC(O)NH2), as well as unreacted starting urea, but these species are unstable at 400 °C.[2]

Protonation gives a 97:3 mixture (at room temperature) of two tautomers, HNCO and NCOH. The more abundant tautomer trimerizes to give cyanuric acid.

Properties[edit]

Potassium carbonate crystals are destroyed by the melting process so that the urea can react with almost all potassium ions to convert to potassium cyanate at a higher rate than when in the form of a salt. This makes it easier to reach higher purities above 95%. It can also be made by oxidizing potassium cyanide at a high temperature in the presence of oxygen or easily reduced oxides, such as lead, tin, or manganese dioxide, and in aqueoues solution by reacting with hypochlorites or hydrogen peroxide. Another way to synthesize it is to allow an alkali metal, cyanide, to react with oxygen in nickel containers under controlled conditions. It can be formed by the oxidation of ferrocyanide. Lastly, it can be made by heating potassium cyanide with lead oxide.[8]

References[edit]

  1. ^ Recreation of Wöhler’s Synthesis of Urea: An Undergraduate Organic Laboratory Exercise James D. Batchelor, Everett E. Carpenter, Grant N. Holder, Cassandra T. Eagle, Jon Fielder, Jared Cummings The Chemical Educator 1/Vol .3,NO.6 1998 ISSN 1430-4171 Online article
  2. ^ a b c Peter M. Schalke1, "Cyanates, Inorganic Salts" Ullmann's Encyclopedia of Industrial Chemistry2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a08_157.pub2. Article Online Posting Date: July 15, 2006
  3. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419. 
  4. ^ Jursík, F. (2001). Anorganická chemie nekovů (1. vydání). VŠCHT Praha. ISBN 80-7080-417-3
  5. ^ T. C. Waddington "Lattice parameters and infrared spectra of some inorganic cyanates" J. Chem. Soc., 1959, 2499-2502. doi:10.1039/JR9590002499
  6. ^ INEOS Paraform GmbH, Potassium Cyanate (KOCN) product information. Online version accessed on 2009-06-30.
  7. ^ "Potassium Cyanate"
  8. ^ "Potassium cyanate" http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=11378442&loc=ec_rcs

External links[edit]