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Sorbate

Sorbic acid
Sorbic acid
Sorbic acid (ball-and-stick model)
Names
IUPAC name
(2E,4E)-hexa-2,4-dienoic acid
Identifiers
110-44-1 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:38358 N
ChEMBL ChEMBL250212 N
ChemSpider 558605 YesY
ECHA InfoCard 100.003.427
E number E200 (preservatives)
PubChem 643460
UNII X045WJ989B YesY
Properties
C6H8O2
Molar mass 112.13 g·mol−1
Melting point 135 °C (275 °F; 408 K)
Boiling point 228 °C (442 °F; 501 K)
Acidity (pKa) 4.76 at 25 °C
Hazards
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Sorbic acid, or 2,4-hexadienoic acid, is a natural organic compound used as a food preservative. It has the chemical formula C6H8O2. It is a colourless solid that is slightly soluble in water and sublimes readily. It was first isolated from the unripe berries of the rowan tree (Sorbus aucuparia), hence its name.

The traditional route to sorbic acid involves condensation of malonic acid and trans-butenal. It can also be prepared from isomeric hexadienoic acids, which are available via a nickel-catalyzed reaction of allyl chloride, acetylene, and carbon monoxide. The route used commercially, however, is from crotonaldehyde and ketene. An estimated 30,000 tons are produced annually.

Sorbic acid was isolated in 1859 by distillation of rowanberry oil by A. W. von Hofmann. This affords the lactone of sorbic acid, which he converted to sorbic acid by hydrolysis. Its antimicrobial activities were discovered in the late 1930s and 1940s, and it became commercially available in the late 1940s and 1950s. Beginning in the 1980s, sorbic acid and its salts were used as inhibitors of Clostridium botulinum in meat products to replace the use of nitrites, which can produce carcinogenic nitrosamines.

With a pKa of 4.76, it is about as acidic as acetic acid.

Sorbic acid and its salts, such as sodium sorbate, potassium sorbate, and calcium sorbate, are antimicrobial agents often used as preservatives in food and drinks to prevent the growth of mold, yeast, and fungi. In general the salts are preferred over the acid form because they are more soluble in water, but the active form is the acid. The optimal pH for the antimicrobial activity is below pH 6.5. Sorbates are generally used at concentrations of 0.025% to 0.10%. Adding sorbate salts to food will, however, raise the pH of the food slightly so the pH may need to be adjusted to assure safety. It is found in many other foods, such as cheeses and breads.


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