Potassium acetate

Potassium acetate (CH3COOK) is the potassium salt of acetic acid.

Potassium acetate
Names
Other names
Potassium salt, E261
Identifiers
CAS Number
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.004.385
E number E261 (preservatives)
PubChem CID
UNII
CompTox Dashboard (EPA)
Properties
Chemical formula
 C2H3KO2
Molar mass 98.142 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
Solubility in water
 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
Heat capacity (C)
 109.38 J/mol·K[3]
Std molar
entropy (So298)
 150.82 J/mol·K[3]
Std enthalpy of
formation (ΔfH⦵298)
 −722.6 kJ/mol[1]
Pharmacology
ATC code
 B05XA17 (WHO)
Hazards
NFPA 704 (fire diamond)
1
1
0
Lethal dose or concentration (LD, LC):
LD50 (median dose)
 3250 mg/kg (oral, rat)[4]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

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.

The sesquihydrate in water solution (CH3COOK·1½H2O) begins to form semihydrate at 41.3 °C.[2]

Applications

Deicing

Potassium acetate can be used as a deicer to remove ice and prevent its formation. It is a substitute for chloride salts such as calcium chloride or magnesium chloride in deicing applications. 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.

Fire extinguishing

Potassium acetate is 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;[5] it is also approved for usage in the USA[6] and Australia and New Zealand.[7] 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.[8] For example, Lenin's mummy was soaked in a bath containing potassium acetate.[9]

Use in executions

Potassium acetate was incorrectly used in place of potassium chloride when putting a prisoner to death in Oklahoma in January 2015.[10] In August 2017, the U.S. state of Florida executed Mark James Asay using a combination of etomidate, rocuronium bromide, and potassium acetate.[11]

Industry

Potassium acetate is used as a catalyst in the production of polyurethanes.[12]

Historical

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

References
  1. http://chemister.ru/Database/properties-en.php?dbid=1&id=504
  2. Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand.
  3. Acetic acid, potassium salt in Linstrom, Peter J.; Mallard, William 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. UK Food Standards Agency: "Current EU approved additives and their E Numbers". Retrieved 2011-10-27.
  6. US Food and Drug Administration: "Listing of Food Additives Status Part II". Retrieved 2011-10-27.
  7. Australia New Zealand Food Standards Code"Standard 1.2.4 - Labelling of ingredients". Retrieved 2011-10-27.
  8. Dale Ulmer (1994). "Fixation. The Key to Good Tissue Preservation" (PDF). Journal of the International Society for Plastination. 8 (1): 7–10. Archived from the original (PDF) on 2011-05-16. Retrieved 2017-09-08.
  9. Andrew Nagorski (2007). The Greatest Battle. Simon and Schuster. p. 53.
  10. "Oklahoma used wrong drug in Charles Warner's execution, autopsy report says".
  11. Jason Dearon. "Florida executes convicted killer Mark Asay using new drug". Sun Sentinel.
  12. 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.
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