Potassium benzoate

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.

Potassium benzoate

Names
IUPAC name Potassium benzoate
Identifiers
CAS Number	582-25-2 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL2105241
ChemSpider	10921 Y
ECHA InfoCard	100.008.621
EC Number	209-481-3
E number	E212 (preservatives)
KEGG	D05576
PubChem CID	23661960
UNII	763YQN2K7K Y
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 Y Key: XAEFZNCEHLXOMS-UHFFFAOYSA-M Y 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	C7H5KO2
Molar mass	160.213 g·mol−1
Appearance	White hygroscopic solid
Odor	Odorless[1]
Density	1.5 g/cm3
Melting point	>300 °C (572 °F; 573 K)[2] (autoignition)
Boiling point	>465 °C (869 °F; 738 K) (1 atm)[2] (decomposes)
Solubility in water	69.87 g/100 mL (17.5 °C (63.5 °F)) 73.83 g/100 mL (25 °C (77 °F)) 79 g/100 mL (33.3 °C (91.9 °F)) 88.33 g/100 mL (50 °C (122 °F))[1][3][page needed]
Solubility in ethanol	soluble
Solubility in methanol	slightly soluble
Solubility in ether	insoluble
Hazards[4]
Occupational safety and health (OHS/OSH):
Main hazards	Low toxicity
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319
Precautionary statements	P264, P264+P265, P280, P302+P352, P305+P351+P338, P321, P332+P317, P337+P317, P362+P364
NFPA 704 (fire diamond)	2 1 0
Autoignition temperature	>300 °C (572 °F; 573 K)[2]
Lethal dose or concentration (LD, LC):
LC50 (median concentration)	484 mg/l (fathead minnow, 96h)[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

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.^[5]

Synthesis

One very common way to make potassium benzoate is by oxidizing toluene to benzoic acid followed by a neutralization with potassium hydroxide:^[6]

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^{[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%.

Safety and health

Potassium benzoate has low acute toxicity upon oral and dermal exposure.^[7] It is a mild irritant to the skin, and has the potential to cause serious eye damage.^[2]

See also

• Sodium benzoate
• Benzoic acid