Potassium benzoate
| Potassium benzoate | |
|---|---|
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| IUPAC name Potassium benzoate | |
| Other names Benzoic acid, potassium salt | |
| Identifiers | |
| CAS number | 582-25-2  |
| PubChem | 23661960 |
| ChemSpider | 10921 |
| UNII | 763YQN2K7K |
| EC number | 209-481-3 |
| Jmol-3D images | {{#if:[K+].[O-]C(=O)c1ccccc1|Image 1 |
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| Properties | |
| Molecular formula | C7H5KO2 |
| Molar mass | 160.21 g mol−1 |
| Appearance | White hygroscopic solid |
| Odor | Odorless[1] |
| Density | 1.5 g/cm3 |
| Melting point | > 300 °C |
| Solubility in water | 65 g/100 mL (20 °C)[1] |
| Solubility | Soluble in ethanol Slightly soluble in methanol Insoluble in ether |
| Hazards | |
| NFPA 704 |
 1
2
0
|
| Autoignition temperature | >950 °C (1,740 °F)[1] |
(verify) (what is: / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |
| 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. In the EU, it is not recommended for consumption by children.[2]
Potassium benzoate is also used as the whistle in many fireworks.[3]
Synthesis
One very common way to make potassium benzoate is by oxidizing toluene.[4]
Another way to synthesize potassium benzoate in the lab setting is by reacting methyl benzoate with potassium thioacetate.[5]
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 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".[6]
Cats have a significantly lower tolerance to benzoic acid and its salts than rats and mice.[7]
Spectra
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.[8]
Infrared spectrum
The following are the main peaks in the IR spectrum.[8]
See also
References
- ↑ 1.0 1.1 1.2 MSDS for potassium benzoate
- ↑ "Final Report on the Safety Assessment of Benzyl Alcohol, Benzoic Acid, and Sodium Benzoate". International Journal of Toxicology 20 (4): 23. 2001. doi:10.1080/10915810152630729.
- ↑ Press Release from Defense Technical Information Center; article- Potassium Benzoate for Pyrotechnic Whistling Compositions: Its Synthesis and Characterization as an Anhydrous Salt
- ↑ 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.
- ↑ 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.
- ↑ 8.0 8.1 SciFinder - Carbon 13 NMR Spectrum for 582-25-2