Potassium acetate

Potassium acetate
Names
Other names
Potassium salt, E261
Identifiers
ATC code B05XA17
127-08-2 Yes
ChEMBL ChEMBL1201058 
ChemSpider 29104 
Jmol-3D images Image
PubChem 31371
Properties
Molecular formula
 C2H3KO2
Molar mass 98.14 g·mol−1
Appearance White deliquescent crystalline powder
Density 1.8 g/cm3 (20 °C)[1]
1.57 g/cm3 (25 °C)
Melting point 292 °C (558 °F; 565 K)
Boiling point Decomposes
216.7 g/100 mL (0.1 °C)
233.8 g/100 mL (10 °C)
268.6 g/100 mL (25 °C)
320.8 g/100 mL (40 °C)
390.7 g/100 mL (96 °C)[2]
Solubility Soluble in alcohol, liquid ammonia
Insoluble in ether, acetone
Solubility in methanol 24.24 g/100 g (15 °C)
53.54 g/100 g (73.4 °C)[1]
Solubility in ethanol 16.3 g/100 g[1]
Solubility in sulfur dioxide 0.06 g/kg (0 °C)[1]
Acidity (pKa) 4.76
Structure
Crystal structure Monoclinic
Thermochemistry
Specific
heat capacity (C)
 109.38 J/mol·K[3]
150.82 J/mol·K[3]
Std enthalpy of
formation (ΔfHo298)
 -722.6 kJ/mol[1]
Hazards
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
1
2
0
3250 mg/kg (oral, rat)[4]
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
  verify (what is: Yes/?)
Infobox references

Potassium acetate (KCH3COO) is the potassium salt of acetic acid.

Preparation

It can be prepared by treating a potassium-containing base such as potassium hydroxide or potassium carbonate with acetic acid:

CH3COOH + KOH → CH3COOK + H2O

This sort of reaction is known as an acid-base neutralization reaction. Sesquihydrate in water solution (CH3COOK·1½H2O) begins to form semihydrate at 41.3 °C.[2] Potassium acetate is the salt that forms along with water as acetic acid and potassium hydroxide are neutralized together.

Conditions/substances to avoid are: moisture, heat, flames, ignition sources, and strong oxidizing agents.

Applications

Potassium acetate is used as a catalyst in the production of polyurethanes.[5]

Potassium acetate can be used as a deicer instead of chloride salts such as calcium chloride or magnesium chloride. It offers the advantage of being less aggressive on soils and much less corrosive, and for this reason is preferred for airport runways. It is, however, more expensive. Potassium acetate is also the extinguishing agent used in class K fire extinguishers because of its ability to cool and form a crust over burning oils.

Food additive

Potassium acetate is used as a food additive as a preservative and acidity regulator. In the European Union, it is labeled by the E number E261;[6] it is also approved for usage in the USA[7] and Australia and New Zealand.[8] Potassium hydrogen diacetate (CAS #4251-29-0 ) with formula KH(OOCCH3)2 is a related food additive with the same E number as potassium acetate.

Medicine and biochemistry

In medicine, potassium acetate is used as part of replacement protocols in the treatment of diabetic ketoacidosis because of its ability to break down into bicarbonate and help neutralize the acidotic state.

In molecular biology, potassium acetate is used to precipitate dodecyl sulfate (DS) and DS-bound proteins, allowing the removal of proteins from DNA. It is also used as a salt for the ethanol precipitation of DNA.

Potassium acetate is used in mixtures applied for tissue preservation, fixation, and mummification. Most museums today use the formaldehyde-based method recommended by Kaiserling in 1897 which contains potassium acetate.[9] For example, Lenin's mummy was soaked in a bath containing potassium acetate.[10]

Historical

Potassium acetate was originally used in the preparation of Cadet's fuming liquid, the first organometallic compound produced. It is used as diuretic and urinary alkaliser, and acts by changing the physical properties of the body fluids and by functioning as an alkali after absortion.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 http://chemister.ru/Database/properties-en.php?dbid=1&id=504
  2. ↑ 2.0 2.1 Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand.
  3. ↑ 3.0 3.1 Acetic acid, potassium salt in Linstrom, P.J.; Mallard, W.G. (eds.) NIST Chemistry WebBook, NIST Standard Reference Database Number 69. National Institute of Standards and Technology, Gaithersburg MD. http://webbook.nist.gov (retrieved 2014-05-18)
  4. ↑ http://chem.sis.nlm.nih.gov/chemidplus/rn/127-08-2
  5. ↑ Hosea Cheung, Robin S. Tanke, G. Paul Torrence "Acetic Acid" in Ullmann's Encyclopedia of Industrial Chemistry 2005 Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_045.
  6. ↑ UK Food Standards Agency: "Current EU approved additives and their E Numbers". Retrieved 2011-10-27.
  7. ↑ US Food and Drug Administration: "Listing of Food Additives Status Part II". Retrieved 2011-10-27.
  8. ↑ Australia New Zealand Food Standards Code"Standard 1.2.4 - Labelling of ingredients". Retrieved 2011-10-27.
  9. ↑ Dale Ulmer, "Fixation. The Key to Good Tissue Preservation.", Journal of the International Society for Plastination, Vol 8 (1): 7-10, 1994
  10. ↑ Andrew Nagorski, The Greatest Battle, Simon and Schuster, 2007, page 53.

External links

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