Potassium acetate

Potassium acetate (CH3COOK) is the potassium salt of acetic acid. It is a hygroscopic solid under room temperature.

Potassium acetate
Names
Other names
Potassium salt, E261
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.004.385
E number E261 (preservatives)
UNII
Properties
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
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
Monoclinic
Thermochemistry
109.38 J/mol·K[3]
150.82 J/mol·K[3]
−722.6 kJ/mol[1]
Pharmacology
B05XA17 (WHO)
Hazards
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Lethal dose or concentration (LD, LC):
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 (as a substitute for calcium chloride or magnesium chloride) for can be used as a deicer to remove ice and prevent its formation. It offers the advantage of being less aggressive on soils and much less corrosive: for this reason, it is preferred for airport runways although it is 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 in processed foods 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] 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 electrolyte replacement protocols in the treatment of diabetic ketoacidosis because of its ability to break down to bicarbonate to help neutralize the acidotic state.

In molecular biology, potassium acetate is used to precipitate dodecyl sulfate (DS) and DS-bound proteins to extract ethanol from DNA.

Potassium acetate is used in mixtures applied for tissue preservation, fixation, and mummification. Most museums today use aformaldehyde-based method recommended by Kaiserling in 1897 which contains potassium acetate.[8] This process was used to soak Lenin's corpse.[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

It is used as a diuretic and urinary alkalizer. Originally it was used in the preparation of Cadet's fuming liquid, the first organometallic compound produced.

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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