What Is Sorbic Acid?

2026-09-20

Sorbic acid (CAS 110-44-1) is a white crystalline powder with a slight characteristic odor; it is soluble in ethanol and ether, insoluble in water; it is hygroscopic and prone to oxidation and discoloration in air. It is prepared using the acetone method, in which acetic acid is cracked at high temperatures to produce acetone, which is then condensed with crotonaldehyde and hydrolyzed and purified. As an acid-type food preservative, its antibacterial action is achieved by inhibiting the growth of molds and yeasts. It is suitable for acidic environments with a pH of 5–6 or lower and is widely used in the food, pharmaceutical, cosmetics, and feed industries.

How Is Sorbic Acid Made?

Preparation of Acetone Gas

Glacial acetic acid (acetic acid) is fed into a cracking tube as the raw material and undergoes thermal cracking at high temperatures of 700°C to 800°C under reduced pressure, resulting in dehydration and the production of highly reactive acetone gas.

Condensation Reaction

In a liquid solution of crotonaldehyde (2-butenal), a condensation reaction is carried out at 30°C to 40°C, resulting in a viscous adipic acid polyester intermediate.

Depolymerisation and Acid Hydrolysis (Crude Product Formation)

The polyester obtained from the condensation reaction is added to concentrated hydrochloric acid or a solid acid catalyst, and an acid hydrolysis reaction is carried out under heated conditions. During this process, the long chains of the polyester are broken down, hydrolysed, and converted into a crude 2,4-hexadienoic acid product, while a portion of black, tar-like material is produced as a byproduct.

Purification and Decolorisation

Since the crude product contains tar and impurities, these must be removed through ethanol washing, hot solvent extraction, or decolorisation with activated carbon. Finally, after cooling and crystallisation, centrifugation, and drying, a high-purity, white, crystalline hexadienoic acid (sorbic acid) product is obtained.

Properties

Melting point	132-135°C (lit.)
Boiling point	228°C
Density	1.2 g/cm³ at 20°C
vapour pressure	0.01 mm Hg (20°C)
refractive index	1.4600 (estimate)
Flash point	127°C
storage temp.	2-8°C
solubility	ethanol: 0.1 g/mL, clear
PH	3.3 (1.6 g/L, H₂O, 20°C)
Odour	bland
biological source	synthetic
Water Solubility	1.6 g/L (20ºC)

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Risk and Safety Statements

Symbol (GHS)	GHS07
Signal word	Warning
Hazard statements	H315-H319
Precautionary statements	P264-P280-P302+P352-P305+P351+P338-P332+P313-P337+P313
PPE	dust mask type N95 (US), Eyeshields, gloves
Hazard Codes	Xi
Risk Statements	36/37/38-36/38
Safety Statements	26-36-24/25
WGK Germany	1
F	8
Autoignition Temperature	>130 °C
Storage Class	11 - Combustible Solids
Hazard Classifications	Eye Irritation. 2 Skin Irritation. 2

What Is Sorbic Acid Used For?

Sorbic acid has a powerful antimicrobial effect against molds, yeasts, and aerobic spoilage bacteria. Rather than acting as a bactericide, it inhibits the growth of harmful microorganisms; therefore, it has extremely low toxicity. When added within the recommended limits, it poses absolutely no adverse effects on human health and can be used with confidence. Furthermore, its efficacy increases as the pH of the food decreases, extending the shelf life by 2 to 6 times compared to foods without this additive. As an acidic food preservative, its antimicrobial action works by inhibiting the growth of molds and yeasts. It is suitable for acidic environments with a pH of 5–6 or lower and is widely used in the food, pharmaceutical, cosmetics, and feed industries.