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Potassium benzoate

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(Redirected from E212) Chemical compound
Potassium benzoate
Names
IUPAC name Potassium benzoate
Identifiers
CAS Number
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.008.621 Edit this at Wikidata
EC Number
  • 209-481-3
E number E212 (preservatives)
KEGG
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C7H6O2.K/c8-7(9)6-4-2-1-3-5-6;/h1-5H,(H,8,9);/q;+1/p-1Key: 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-1Key: XAEFZNCEHLXOMS-REWHXWOFAQ
SMILES
  • .C(=O)c1ccccc1
Properties
Chemical formula C7H5KO2
Molar mass 160.213 g·mol
Appearance White hygroscopic solid
Odor Odorless
Density 1.5 g/cm
Melting point >300 °C (572 °F; 573 K)
Solubility in water 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
Hazards
Occupational safety and health (OHS/OSH):
Main hazards Low toxicity
GHS labelling:
Pictograms GHS07: Exclamation mark
Signal word Warning
Hazard statements H315, H319
Precautionary statements P264, P280, P302+P352, P305+P351+P338, P332+P313, P337+P313, P362
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 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
Autoignition
temperature 		950 °C (1,740 °F; 1,220 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

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 United States and the European Union, where it is designated by the E number E212.

Potassium benzoate is also used in the whistle in many fireworks.

Synthesis

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

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

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".

Spectra

Carbon-13 NMR

The carbon-13 NMR shows 5 unique peaks. There are four peaks between 130-140 ppm from the carbon atoms in the benzene ring. There is an additional carbon peak around 178 ppm representing the carbon atom from the carbonyl group.

Infrared spectrum

The following are the main peaks in the IR spectrum.

See also

References

  1. ^ "Potassium Benzoate". Emerald Kalama Chemical. Retrieved 2014-06-02.
  2. Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand. Retrieved 2014-05-29.
  3. "Potassium benzoate". pubchem.ncbi.nlm.nih.gov.
  4. Press Release from Defense Technical Information Center; article- Potassium Benzoate for Pyrotechnic Whistling Compositions: Its Synthesis and Characterization as an Anhydrous Salt
  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.
  7. , The Food Magazine, Issue 77, Food Commission UK
  8. ^ SciFinder - Carbon-13 NMR Spectrum for 582-25-2
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