Benzoic acid, C6H5COOH, is a colourless crystalline solid and the simplest aromatic carboxylic acid.
The name derived from gum benzoin which was for a long time the only source for benzoic acid.
The weak acid and its salts are historically used as food preservative and as raw material for several chemical substances like benzoyl chloride and plasticizers.
General Description & Applications:
Benzoic acid, the simplest aromatic carboxylic acid containing carboxyl group bonded directly to benzene ring, is a white, crystalline organic compound; melting at 122 C (starting sublime at 100 C); boiling at 249 C; slightly soluble in water, soluble in ethanol, very slightly soluble in benzene and acetone. Its aqua solution is weakly acidic. It occurs naturally in many plants and resins.
Benzoic acid is also detected in animals. The most of commercial benzoic acid is produced by the reaction of toluene with oxygen at temperatures around 200 C in the liquid phase and in the presence of cobalt and manganese salts as catalysts. It can be prepared also by the oxidation of benzene with concentrated sulphuric acid or carbon dioxide in the presence of catalysts. Other methods are such as by the oxidation of benzyl alcohol, benzaldehyde, cinnamic acid; by hydrolysis of benzonitrile, benzoyl chloride. More than 90% of commercial benzoic acid is converted directly to phenol and caprolactam. Its use in the production of glycol benzoates for the application of plasticizer in adhesive formulations is increasing. It is also used in the manufacture of alkyd resins and drilling mud additive for crude oil recovery applications. It is used as a rubber polymerization activators and retardants.
Benzoic acid is converted to its salts and esters for the use of preservative application in foods, drugs and personal products. Sodium benzoate, sodium salt of benzoic acid, is used preferably as one of the principal anti-microbial preservatives used in foods and beverages (but it's concentration is limited usually not exceeding 0.1% because it is poisonous), as it is about 200 times more soluble than benzoic acid. Sodium Benzoate is also used in medications, anti-fermentation additives and tabletting lubricant for pharmaceuticals. The industrial applications are as a corrosion inhibitor, as an additive to automotive engine antifreeze coolants and in other waterborne systems, as a nucleating agents for polyolefin, as a dye intermediate, as a stabilizer in photographic processing and as a catalyst. Wide range of benzoic esters are used as solvents, dying carrier, disinfectant additive, penetrating agent and pesticides and manufacturing other compounds.
Benzoic acid was discovered in the 16th century. The dry distillation of gum benzoin was first described by Nostradamus (1556), and subsequently by Alexius Pedemontanus (1560) and Blaise de Vigen¨¨re (1596).
Justus von Liebig and Friedrich W?hler determined the structure of benzoic acid in 1832.
In 1875 Salkowski discovered the antifungal abilities of benzoic acid which were used for a long time in the preservation of benzoate containing fruits.
Phenyl carboxylic acid;
White powder or crystals with a strong odor.
Benzoic acid has good anti-microbial features, but because it does not dissolve well in water, sodium benzoate is often used, because in acidic solutions it converts to benzoic acid, and sodium benzoate dissolves very well in water.
Benzoic acid is used as an anti-microbial agent.
It is found in toothpastes and mouthwashes, cosmetics, and deodorants.