Sodium benzoate has the chemical formula NaC7H5O2; it is a widely used food preservative, with E number E211. It is the sodium salt of benzoic acid and exists in this form when dissolved in water. It can be produced by reacting sodium hydroxide with benzoic acid. Benzoic acid occurs naturally at low levels in cranberries, prunes, greengage plums, cinnamon, ripe cloves, and apples.

Sodium benzoate with the CAS Number 532-32-1. Though benzoic acid is a more effective preservative, it isn’t very soluble in cold water compared to sodium benzoate which dissolves easily in water.

1. Properties of Sodium benzoate

Name:Sodium benzoate

EINECS:208-534-8

Molecular Formula:C7H5NaO2

CAS Registry Number:532-32-1 

InChI:InChI=1/C7H6O2.Na/c8-7(9)6-4-2-1-3-5-6;/h1-5H,(H,8,9);/q;+1/p-1

HS Code:29163100

Appearance:White crystalline powder.

Molecular Weight:144.1

Density:1,44 g/cm3

Boiling Point:249.3 °C at 760 mmHg

Melting Point:>300 °C(lit.)

Flash Point:111.4 °C

Storage Temperature:Store at RT.

Solubility:H2O: 1 M at 20 °C, clear, colorless

Stability:Stable, but may be moisture senstive. Incompatible with strong oxidizing agents, alkalis, mineral acids.

Usage:Food preservative, antiseptic, medicine, tobacco, pharmaceutical preparations, intermediate for manufacture of dyes, rust and mildew inhibitor.
2. Preparation of Sodium benzoate
Sodium benzoate is created by adding benzoic acid to a hot concentrated solution of sodium carbonate until effervescence ceases. The solution is then evaporated, cooled and allowed to crystallize or evaporate to dryness, and then granulated.
3. Uses of Sodium benzoate
Sodium benzoate is a preservative. It is bacteriostatic and fungistatic under acidic conditions. It is used most prevalently in acidic foods such as salad dressings (vinegar), carbonated drinks (carbonic acid), jams and fruit juices (citric acid), pickles (vinegar), and condiments. Besides, it is also used in fireworks as a fuel in whistle mix, a powder which emits a whistling noise when compressed into a tube and ignited.
4. Mechanism of food preservation
The mechanism starts with the absorption of benzoic acid into the cell. If the intracellular pH falls to 5 or lower, the anaerobic fermentation of glucose through phosphofructokinase decreases sharply which inhibits the growth and survival of micro-organisms that cause food spoilage.