Sodium Benzoate

Sodium benzoate is a white or colorless crystalline powder. It is a widely used food preservative, E211. It is the sodium salt of Benzoic Acid and exists in this form when dissolved in water. It is used as a preservative in personal care applications and as a corrosion inhibitor in automotive and other antifreeze products.

Synonyms
Sodium Benzoate, Benzoate of Soda, Benzoic Acid, Sodium Salt, Sodium Benzoate, Sodium Salt of Benzoic Acid
Chemical Formula
C7H5NaO2
CAS Number
532-32-1

Characteristics

Molar Weight
144.11 g/mol
Melting Point
436.1°C
Density
1.5 g/cc
Forms
White, Granular

Uses and applications

Key applications

  • Hair care
  • Food additive
  • Corrosion inhibitor and anti-scaling agent
  • Preservative
  • Adhesives and Sealants
  • Anti-fungal agent
  • Fragrance Ingredient
  • Cosmetic products

General information about Sodium benzoate

Sodium benzoate (C7H5NaO2) is the sodium salt of benzoic acid, an organic compound that occurs naturally in many plants, fruits and fermented foods. Sodium benzoate does not occur in nature in its pure form, but is produced industrially in large quantities and used worldwide as a preservative.
The best-known application of sodium benzoate is in the food industry, but it also plays an important role in cosmetics, the pharmaceutical industry and in technical areas such as construction and cleaning chemicals.
Properties of sodium benzoate
Sodium benzoate is a white, odourless, crystalline solid that dissolves easily in water. The substance is slightly hygroscopic (water-attracting) and is considered flammable.
Industrial production involves neutralising benzoic acid with sodium hydroxide (caustic soda) or sodium carbonate in an aqueous solution. This produces the salt sodium benzoate: C6H5COOH + NaOH = CgH5COONa + H2O
In large-scale production, benzoic acid is added directly to a mixture of water and caustic soda. After the reaction, the resulting sodium benzoate is isolated by evaporation and crystallisation and then dried.
Cola soda fizzy drinks cans

Sodium benzoate in the food industry

In the food industry, sodium benzoate has the additive number E 211 and is used as a preservative. It inhibits the growth of bacteria, yeasts and moulds, especially in slightly acidic environments.
At a pH value between 2.5 and 4.5, sodium benzoate is partially converted into benzoic acid. This penetrates the cell membranes of microorganisms, disrupts their energy metabolism and leads to inhibition or killing of the cells.
Typical applications:
  • Beverages: fruit juices, lemonades, energy drinks, cola
  • Sauces and condiments: ketchup, mustard, BBQ sauces, soy sauce
  • Acidic foods: pickled gherkins, olives, sauerkraut
  • Confectionery: jams, jellies, fruit spreads, gelatine products
  • Ready meals: Soups, spice mixes, marinades
Thanks to its antimicrobial effect, sodium benzoate contributes significantly to extending the shelf life and product safety of many foods.
Beautiful Asian Woman Gently Touching Her Face, Looking Away. Young Adult Female with Lush Black Hair Makes Her Skin Soft, Clean with Natural Cosmetics Skincare Product. Close-up Portrait

Sodium benzoate in the cosmetics industry

Sodium benzoate is also used as a preservative in the cosmetics industry to prevent microbial spoilage in aqueous or acidic formulations. It is considered well tolerated and is approved for use in both natural cosmetics and conventional care products. Areas of application include:
  • Skin care: moisturisers, exfoliants, cleansing gels
  • Hair care: shampoos, conditioners, styling products
  • Body care: shower gels, bubble baths, deodorants
  • Hand and oral care: hand soaps, toothpastes, mouthwashes
Sodium benzoate prevents the formation of bacteria and mould and contributes to the stability and shelf life of cosmetic formulations.

Sodium benzoate in the construction industry

In construction chemistry, sodium benzoate is used as a corrosion inhibitor and stabiliser. It protects metal reinforcements in concrete and cement mixtures from corrosion by forming a passivating protective layer on the steel surface. Important applications include, for example:
  • Concrete additives: protection of reinforcements against moisture and chemicals
  • Hydraulic systems: corrosion protection in water-based cooling and hydraulic solutions
  • Coatings and paints: improving the corrosion resistance of metals
  • Antifreeze: component in antifreeze additives for concrete
  • Sealants and primers: stabilising and extending the service life of coatings
Sodium benzoate is also used in the manufacture of adhesives and sealants, where it acts as a preservative and stabiliser.

Other areas of application for sodium benzoate

Sodium benzoate is also used in numerous other areas where microbial protection and chemical stability are crucial.
  • Pharmaceutical industry: Here, sodium benzoate serves as a preservative in liquid medicines such as cough syrups, eye drops and nasal sprays. It is also used in topical preparations, such as creams for fungal infections, to prevent microbial growth.
  • Animal nutrition: In livestock farming, sodium benzoate is used to prevent mould in feed and silage. It helps to ensure feed quality and increase storage stability.
  • Cleaning and household care: In the cleaning industry, sodium benzoate is used in detergents, fabric softeners and cleaning agents as a preservative and stability additive. It also stabilises fragrances in water-based formulations in air fresheners and room sprays.

Summary

Sodium benzoate is a versatile chemical salt with high industrial significance. Its main application is in food preservation, but it is also valued in cosmetics, construction, pharmaceutical and cleaning products due to its antimicrobial and corrosion-inhibiting properties.