Potassium benzoate

Potassium benzoate
Names
	IUPAC name Potassium benzoate
Identifiers
CAS Number	582-25-2 ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL2105241;
ChemSpider	10921 ;
ECHA InfoCard	100.008.621
EC Number	209-481-3;
E number	E212 (preservatives)
KEGG	D05576;
PubChem CID	23661960;
UNII	763YQN2K7K ;
CompTox Dashboard (EPA)	DTXSID1027219 ;
	InChI InChI=1S/C7H6O2.K/c8-7(9)6-4-2-1-3-5-6;/h1-5H,(H,8,9);/q;+1/p-1 Key: XAEFZNCEHLXOMS-UHFFFAOYSA-M ; 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;
	SMILES [K+].[O-]C(=O)c1ccccc1;
Properties
Chemical formula	C6H5COOK
Molar mass	160.213 g·mol−1
Appearance	White solid
Odor	Odorless
Density	1.56 g/cm3 (20 °C (68 °F; 293 K))
Melting point	>300 °C (572 °F; 573 K)
Boiling point	>465 °C (869 °F; 738 K) (decomposes)
Solubility in water	5.04 g/100g (0.86 °C (33.55 °F; 274.01 K), solid); 39.89 g/100g (8.5 °C (47.3 °F; 281.6 K), melting point); 40.6 g/100g (13.0 °C (55.4 °F; 286.1 K)); 44.92 g/100g (41.0 °C (105.8 °F; 314.1 K)); 53.5 g/100g (97.5 °C (207.5 °F; 370.6 K)); 66.09 g/100g (181.0 °C (357.8 °F; 454.1 K));
Solubility in ethanol	soluble
Solubility in methanol	slightly soluble
Solubility in ether	insoluble
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H315, H318
Precautionary statements	P264, P280, P302+P352, P305+P351+P338+P310, P332+P313, P362
NFPA 704 (fire diamond)	0 1 1
Threshold limit value (TLV)	2.5 mg/m3 (skin) (TWA)
Related compounds
Other anions	Sodium benzoate; Copper benzoate;
Other cations	Potassium hydrogen phthalate; Potassium salicylate;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Potassium benzoate (E212), the potassium salt of benzoic acid with the formula C₆H₅COOK, 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.

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. Compared to the other carboxylic acid salts, sodium salicylate and sodium benzoate often used for this purpose, it has the advantage of not being hygroscopic.^[4]

Synthesis

One very common way to make potassium benzoate is by oxidizing toluene to benzoic acid followed by a neutralization with potassium hydroxide:^[5]

C₆H₅COOH + KOH → C₆H₅COOK + H₂O

Another way to synthesize potassium benzoate in the lab setting is by hydrolyzing methyl benzoate with potassium hydroxide:^{[citation needed]}

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%.^{[citation needed]}

Safety and health

Potassium benzoate has low acute toxicity upon oral and dermal exposure.^[6] It is a mild irritant to the skin, and has the potential to cause serious eye damage.^[1]

References

1 2 3 4 "Safety Data Sheet: Potassium Benzoate". www.sigmaaldrich.com. Sigma-Aldrich. p. 6.
↑ Seidell, Atherton; Linke, William F. (1958). Solubilities of Inorganic and Organic Compounds; A Compilation of Quantitative Solubility Data From the Periodical Literature (4th ed.). Van Nostrand. p. 1352. OL 47062711M. Retrieved 19 March 2026.
1 2 "SDS - Potassium Benzoate" (pdf). www.thermofisher.com. ThermoFisher Scientific. 24 December 2025. pp. 2–3. Retrieved 19 March 2026.
↑ 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.
↑ US 3867439, Hills, David J., "Preparation of potassium benzoate", published 1975-02-18, assigned to The Dow Chemical Company
↑ "Benzoates" (PDF). United Nations Environment Programme. Archived from the original (PDF) on 2018-03-07. Retrieved 2015-04-30.

[SigmaSDS-1] 1 2 3 4 "Safety Data Sheet: Potassium Benzoate". www.sigmaaldrich.com. Sigma-Aldrich. p. 6.

[sioc-2] Seidell, Atherton; Linke, William F. (1958). Solubilities of Inorganic and Organic Compounds; A Compilation of Quantitative Solubility Data From the Periodical Literature (4th ed.). Van Nostrand. p. 1352. OL 47062711M. Retrieved 19 March 2026.

[FisherSDS-3] 1 2 "SDS - Potassium Benzoate" (pdf). www.thermofisher.com. ThermoFisher Scientific. 24 December 2025. pp. 2–3. Retrieved 19 March 2026.

[4] 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.

[5] US 3867439, Hills, David J., "Preparation of potassium benzoate", published 1975-02-18, assigned to The Dow Chemical Company

[6] "Benzoates" (PDF). United Nations Environment Programme. Archived from the original (PDF) on 2018-03-07. Retrieved 2015-04-30.

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Synthesis

Reactions

Mechanism of food preservation

Safety and health

See also

References