Potassium benzoate

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Potassium benzoate
Potassium benzoate.png
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Potassium benzoate.jpg
Names
IUPAC name
Potassium benzoate
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.008.621 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 209-481-3
E number E212 (preservatives)
KEGG
PubChem CID
UNII
  • InChI=1S/C7H6O2.K/c8-7(9)6-4-2-1-3-5-6;/h1-5H,(H,8,9);/q;+1/p-1 Yes check.svgY
    Key: XAEFZNCEHLXOMS-UHFFFAOYSA-M Yes check.svgY
  • InChI=1/C7H6O2.K/c8-7(9)6-4-2-1-3-5-6;/h1-5H,(H,8,9);/q;+1/p-1
    Key: XAEFZNCEHLXOMS-REWHXWOFAQ
  • [K+].[O-]C(=O)c1ccccc1
Properties
C7H5KO2
Molar mass 160.213 g·mol−1
AppearanceWhite hygroscopic solid
Odor Odorless [1]
Density 1.5 g/cm3
Melting point >300 °C (572 °F; 573 K) [2] (autoignition)
Boiling point >465 °C (869 °F; 738 K) (1 atm) [2] (decomposes)
  • 69.87 g/100 mL (17.5 °C (63.5 °F))
  • 73.83 g/100 mL (25 °C (77 °F))
  • 79 g/100 mL (33.3 °C (91.9 °F))
  • 88.33 g/100 mL (50 °C (122 °F)) [1] [3] [ page needed ]
Solubility in ethanol soluble
Solubility in methanol slightly soluble
Solubility in ether insoluble
Hazards [4]
Occupational safety and health (OHS/OSH):
Main hazards
Low toxicity
GHS labelling:
GHS-pictogram-exclam.svg
Warning
H315, H319
P264, P264+P265, P280, P302+P352, P305+P351+P338, P321, P332+P317, P337+P317, P362+P364
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
1
0
>300 °C (572 °F; 573 K) [2]
Lethal dose or concentration (LD, LC):
484 mg/l (fathead minnow, 96h) [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Potassium benzoate (E212), the potassium salt of benzoic acid, is a food preservative that inhibits the growth of mold, yeast and some bacteria. It works best in low-pH products, below 4.5, where it exists as benzoic acid.

Contents

Acidic foods and beverages such as fruit juice (citric acid), sparkling drinks (carbonic acid), soft drinks (phosphoric acid), and pickles (vinegar) may be preserved with potassium benzoate. It is approved for use in most countries including Canada, the United States and the European Union, where it is designated by the E number E212.

Potassium benzoate is also used in whistle compositions in pyrotechnics. [5]

Synthesis

One very common way to make potassium benzoate is by oxidizing toluene to benzoic acid followed by a neutralization with potassium hydroxide: [6]

C6H5COOH + KOH → C6H5COOK + H2O

Another way to synthesize potassium benzoate in the lab setting is by hydrolyzing methyl benzoate with potassium hydroxide:

C6H5COOCH3 + KOH → C6H5COOK + CH3OH

Reactions

Potassium benzoate, like sodium benzoate, can be decarboxylated with a strong base and heat:

C6H5COOK + KOH → C6H6 + K2CO3[ citation needed ]

Mechanism of food preservation

The mechanism of food preservation begins with the absorption of benzoic acid into the cell. If the intracellular pH changes to 5 or lower, the anaerobic fermentation of glucose through phosphofructokinase is decreased by 95%. [7]

Safety and health

Potassium benzoate has low acute toxicity upon oral and dermal exposure. [8] It is a mild irritant to the skin, and has the potential to cause serious eye damage. [2]

See also

References

  1. 1 2 "Potassium Benzoate". Emerald Kalama Chemical. Retrieved 2014-06-02.
  2. 1 2 3 4 5 "Safety Data Sheet: Potassium Benzoate". www.sigmaaldrich.com. Sigma-Aldrich. p. 6.
  3. ↑ Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand. Retrieved 2014-05-29.
  4. ↑ "Potassium benzoate". pubchem.ncbi.nlm.nih.gov.
  5. ↑ Whelan, D.J.; Elischer, P.P. (February 1983). "Potassium Benzoate for Pyrotechnic Whistling Compositions: Its Synthesis and Characterization as an Anhydrous Salt". apps.dtic.mil. Melbourne, Victoria, Australia: Department of Defence, Defence Science and Technology Organisation, Materials Research Labs. Retrieved 27 July 2025.
  6. ↑ US 3867439,Hills, David J.,"Preparation of potassium benzoate",published 1975-02-18, assigned to The Dow Chemical Company
  7. ↑ "Potassium_benzoate". www.chemeurope.com. Retrieved 2025-10-02.
  8. ↑ "Benzoates" (PDF). United Nations Environment Programme. Archived from the original (PDF) on 2018-03-07. Retrieved 2015-04-30.
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