Potassium benzoate

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Potassium benzoate
Potassium benzoate.png
Potassium benzoate ball-and-stick.png
Potassium benzoate.jpg
IUPAC name
Potassium benzoate
Other names
Potassium salt
582-25-2 YesY
ChemSpider 10921 YesY
EC number 209-481-3
Jmol-3D images Image
PubChem 23661960
Molar mass 160.21 g·mol−1
Appearance White hygroscopic solid
Odor Odorless[1]
Density 1.5 g/cm3
Melting point >300 °C (572 °F; 573 K)
69.87 g/100 mL (17.5 °C)
73.83 g/100 mL (25 °C)
79 g/100 mL (33.3 °C)
88.33 g/100 mL (50 °C)[2][1]
Solubility in other solvents Soluble in ethanol
Slightly soluble in methanol
Insoluble in ether
Vapor pressure 1.6 Pa[3]
S-phrases S22-S24/25
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
Flash point 111.4 °C (232.5 °F; 384.5 K) [3]
950 °C (1,740 °F; 1,220 K)
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

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.

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 U.S., and the EU, where it is designated by the E number E212.

Potassium benzoate is also used in the whistle in many fireworks.[4]


One very common way to make potassium benzoate is by oxidizing toluene.[5]

Another way to synthesize potassium benzoate in the lab setting is by reacting methyl benzoate with potassium thioacetate.[6]

Mechanism of food preservation[edit]

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%.

Safety and health[edit]

Potassium benzoate was recently described by the Food Commission, who campaign for 'safer, healthier food in the UK', as "mildly irritant to the skin, eyes and mucous membranes".[7]

Cats have a significantly lower tolerance to benzoic acid and its salts than rats and mice.[8]


Carbon 13 NMR[edit]

The carbon NMR shows 5 unique peaks. There are four peaks between 130-140 ppm from the carbons in the benzene ring. There is an additional carbon peak around 178 ppm representing the carbon from the carbonyl.[9]

Infrared spectrum[edit]

The following are the main peaks in the IR spectrum.[9]

See also[edit]


  1. ^ a b "POTASSIUM BENZOATE". http://www.emeraldmaterials.com/. Emerald Kalama Chemical, LLC. Retrieved 2014-06-02. 
  2. ^ Seidell, Atherton; Linke, William F. (1952). [Google Books Solubilities of Inorganic and Organic Compounds]. Van Nostrand. Retrieved 2014-05-29. 
  3. ^ a b "582-25-2 Potassium benzoate". http://www.chemnet.com/. Zhejiang NetSun Co., Ltd. Retrieved 2014-06-02. 
  4. ^ Press Release from Defense Technical Information Center; article- Potassium Benzoate for Pyrotechnic Whistling Compositions: Its Synthesis and Characterization as an Anhydrous Salt
  5. ^ Preparation of potassium benzoate, US 3867439 
  6. ^ Bhattacharya, Apurba; Patel, Nitin C.; Vasques, Tomas; Tichkule, Ritesh; Parmar, Gaurang; Wu, Jiejun (2006). "Surfactant-mediated solvent-free dealkylative cleavage of ethers and esters and transalkylation under neutral conditions". Tetraderon Letters 47 (4): 565–567. doi:10.1016/j.tetlet.2005.11.048. 
  7. ^ Published in The Food Magazine issue 77 from the Food Commission UK
  8. ^ Bedford PG, Clarke EG (1972). "Experimental benzoic acid poisoning in the cat". Vet Rec 90 (3): 53–58. doi:10.1136/vr.90.3.53. PMID 4672555. 
  9. ^ a b SciFinder - Carbon 13 NMR Spectrum for 582-25-2