C6H7NO3

C6H7NO3 is the molecular formula for several chemical compounds, with the most common being 4-hydroxybenzoic acid, also known as p-hydroxybenzoic acid or PHBA. This organic compound is a white crystalline solid. It is a monohydroxy derivative of benzoic acid and is an isomer of salicylic acid (2-hydroxybenzoic acid) and m-hydroxybenzoic acid.

4-hydroxybenzoic acid occurs naturally in plants and is a metabolic intermediate in the biosynthesis of various compounds. It is also a precursor to parabens, which are widely used as preservatives in cosmetics, pharmaceuticals, and food products. The ester derivatives of 4-hydroxybenzoic acid are known as parabens, and their antimicrobial properties make them effective in preventing spoilage.

Industrially, 4-hydroxybenzoic acid can be synthesized through several methods, including the Kolbe-Schmitt reaction involving phenol and carbon dioxide. Its applications extend beyond preservatives, finding use in the production of liquid crystal polymers and as an intermediate in the synthesis of other organic chemicals. The compound is soluble in water and organic solvents like ethanol and ether.