Benzoic acid

An aromatic acid organic compound and the simplest aromatic acid with the molecular formula C7H6O2. Originally made from benzoin gum, it is called benzoin acid. The appearance is white needle-like or scale-like crystal.

Benzoic acid exists widely in nature in the form of free acids, esters, or their derivatives. It is mainly used in the preparation of sodium benzoate preservatives and in the synthesis of drugs and dyes, as well as plasticizers, mordants, fungicides, and spices. It can be prepared by direct oxidation of toluene in the presence of manganese dioxide or by decarboxylation of phthalic anhydride with steam. Benzoic acid and sodium benzoate can kill bacteria and inhibit the growth of bacteria, and they are low toxic and tasteless, so they are widely used as preservatives. In a slightly acidic medium, only 0.1% benzoic acid can inhibit bacterial growth. The change of pH value has a great influence on the bactericidal and bacteriostatic effect of benzoate, which decreases obviously in the reducing medium, and the effect is the best when the pH value is 2.5-4.5.