C6H5COOK

Potassium benzoate is the potassium salt of benzoic acid, with a chemical formula commonly written as C7H5KO2 or, in shorthand, C6H5COOK. It appears as a white crystalline powder and is soluble in water. In aqueous solution it dissociates into potassium ions and benzoate ions (C6H5COO−). The conjugate acid, benzoic acid, has a pKa of about 4.2, so in acidic environments benzoic acid forms and contributes antimicrobial activity, while at neutral pH the benzoate form predominates.

Preparation of potassium benzoate is achieved by neutralizing benzoic acid with potassium hydroxide. This process yields the salt, which is stable and water-soluble, making it useful in various formulations.

Uses of potassium benzoate are primarily as a food preservative (designated as E212 in the European Union) to inhibit growth of molds, yeasts, and some bacteria in acidic foods and beverages. It is also employed as a preservative in cosmetics and pharmaceutical products. Its effectiveness is enhanced in acidic products and it is often used in combination with other preservatives to broaden antimicrobial coverage.

Safety and regulation: Potassium benzoate generally exhibits low acute toxicity and is regarded as safe for use as a food additive by regulatory authorities within approved limits that vary by product and region. Some individuals may experience hypersensitivity or irritation, and it should be stored away from heat and moisture. As with many preservatives, its efficacy and safety depend on correct usage levels and product pH.