|Molar mass||160.21 g·mol−1|
|Appearance||White hygroscopic solid|
|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)
|Solubility in other solvents||Soluble in ethanol
Slightly soluble in methanol
Insoluble in ether
|Vapor pressure||1.6 Pa|
|Flash point||111.4 °C (232.5 °F; 384.5 K) |
|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)
|what is: / ?)(|
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.
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%.
Safety and health
Potassium benzoate has low acute toxicity upon oral and dermal exposure. The Food Commission, which campaigns for safer, healthier food in the UK, describes potassium benzoate as "mildly irritant to the skin, eyes and mucous membranes".
Under certain circumstances, such as in the presence of ascorbic acid, benzoate salts can produce benzene in soft drinks; however, the levels of benzene measured do not pose a safety concern for consumers.
Carbon 13 NMR
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.
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- Preparation of potassium benzoate, US 3867439
- 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.
- "Benzoates" (PDF). United Nations Environment Programme.
- Published in The Food Magazine issue 77 from the Food Commission UK
- 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.
- "Questions and Answers on the Occurrence of Benzene in Soft Drinks and Other Beverages". Food and Drug Administration.
...the levels of benzene found in beverages to date do not pose a safety concern for consumers.
- SciFinder - Carbon 13 NMR Spectrum for 582-25-2