• Source: 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.
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

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The following are the main peaks in the IR spectrum.

1610: C=O from carbonyl
1580: C=C from benzene ring




See also


Sodium benzoate
Benzoic acid




References

Kata Kunci Pencarian:

• Kamus rumus kimia
• Butil hidroksitoluen
• Potassium benzoate
• Sodium benzoate
• Shasta (drink)
• Benzoic acid
• Benzoates
• Cannizzaro reaction
• Potassium sorbate
• Surge (drink)
• Pibb Xtra
• Calcium benzoate