4-Nitrobenzoic acid, also known as p-nitrobenzoic acid, is an organic compound with the chemical formula C6H4(NO2)CO2H. It belongs to carboxylic acids and is a compound formed by the substitution of nitro groups at the para (4-position) of benzene with carboxylic acid. It is a type of nitrobenzoic acid and is an isomer of ortho-nitrobenzoic acid and meta-nitrobenzoic acid.

• Acidity & Character: p-Nitrobenzoic acid is a pale yellow and odorless crystalline substance. Due to the presence of carboxyl groups, it is acidic. The reason why it is more acidic than benzoic acid is that there is a nitro group on the benzene ring. The nitro group is an electron-withdrawing group, which can make the carboxyl group of p-nitrobenzoic acid more acidic through the conjugation effect.
• Solubility: Yellowish-white crystals. Soluble in ethanol, ether, chloroform, acetone and boiling water, slightly soluble in benzene and dithiocarbon disulfide, and insoluble in petroleum ether.
• Stability: Stable. Flammable. Incompatible with strong oxidants, cyanide, and strong bases.

This product is an intermediate for organic synthesis in the fields of medicine, dyes, veterinary drugs, photosensitive materials, etc. It is used for the production of:

• Procaine hydrochloride, procainamide hydrochloride, p-aminobenzoic acid, folic acid, benzocaine, cough suppressant, cephalosporin V, p-aminobenzoic acid glutamate, and benzinol.
• Reactive brilliant red M-8B and reactive red purple X-2R.
• Filters, color film toners, metal surface rust removers, sunscreens, and other materials.