Sorbic acid

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Sorbic acid
Names
IUPAC name
(2E,4E)-hexa-2,4-dienoic acid
Other names
2E,4E-Hexadienoic acid
Properties
C6H8O2
CH3(CH)4COOH
Molar mass 112.128 g/mol
Appearance White solid
Odor Faint fruity odor
Density 1.204 g/cm3 (20 °C)
Melting point 135 °C (275 °F; 408 K)
Boiling point 228 °C (442 °F; 501 K)
0.156 g/100 ml (20 °C)
0.191 g/100 ml (30 °C)
Solubility Soluble in glacial acetic acid, acetone, dioxane, ethanol, methanol
Slightly soluble in diethyl ether, isopropanol, methyl acetate, propylene glycol
Sparingly soluble in benzene, CCl4, cyclohexane, diisopropyl ether, glycerol, toluene, xylene
Vapor pressure 0.01 mmHg at 20 °C
Acidity (pKa) 4.76
Thermochemistry
Hazards
Safety data sheet Sigma-Aldrich
Flash point 127 °C (260.6 °F; 400 K)
Related compounds
Related compounds
Potassium sorbate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sorbic acid, or 2,4-hexadienoic acid, is a natural occurring organic chemical compound, with the formula CH3(CH)4CO2H

Properties

Chemical

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

Physical

Sorbic acid is a colorless solid that is slightly soluble in water and sublimes readily.

Availability

Sorbic acid is sold as its salt form, potassium sorbate. Can also be bought online.

It can be isolated from the unripe berries of the Sorbus aucuparia (rowan tree), hence its name. Distillation of rowanberry oil affords parasorbic acid, the lactone of sorbic acid, which he converted to sorbic acid by hydrolysis.

Preparation

Sorbic acid can be easily made by acidifying potassium sorbate using a strong acid.

Lab methods involve condensation of malonic acid and trans-butenal, or crotonaldehyde and ketene.

Projects

  • Food preservative
  • Make sorbates (calcium sorbate, potassium sorbate, sodium sorbate)
  • Additive for cold rubber

Handling

Safety

Sorbic acid has low toxicity, though may be irritant.

Storage

In closed plastic bottles.

Disposal

No special disposal is required. Discard it as you wish.

References

Relevant Sciencemadness threads