Sodium Benzoate

There are three methods for the commercial preparation of sodium benzoate. In one method, naphthalene is oxidized with vanadium pentoxide to give phthalic anhydride. This is decarboxylated to yield benzoic acid. In a second method, toluene is mixed with nitric acid and oxidized to produce benzoic acid. In a third method, benzotrichloride is hydrolyzed and then treated with a mineral acid to give benzoic acid. Benzotrichloride is formed by the reaction of chlorine and toluene. In all cases, the benzoic acid is further refined to produce sodium benzoate. One way this is done is by dissolving the acid in a sodium hydroxide solution. The resulting chemical reaction produces sodium benzoate and water. The crystals are isolated by evaporating off the water.