4-Nitrobenzoic acid is an organic compound

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 with the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 C₆H₄(NO₂)CO₂H. It is a precursor to 4-nitrobenzoyl chloride, the precursor to the anestheic Procaine

Procaine

Procaine is a local anesthetic drug of the amino ester group. It is used primarily to reduce the pain of intramuscular injection of penicillin, and it was also used in dentistry. Owing to the ubiquity of the trade name Novocain, in some regions procaine is referred to generically as novocaine...

 and folic acid

Folic acid

Folic acid and folate , as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9...

. It is also a precursor to 4-aminobenzoic acid

4-Aminobenzoic acid

4-Aminobenzoic acid is an organic compound with the formula H2NC6H4CO2H. PABA is a white grey crystalline substance that is only slightly soluble in water...

.
4-Nitrobenzoic acid is prepared by oxidation of 4-nitrotoluene using oxygen or nitric acid as oxidants. Alternatively, it has been prepared by nitration of polystyrene

Polystyrene

Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...

followed by oxidation of the alkyl substituent. This method proceeds with improved para/ortho selectivity owing to the steric protection of the ortho positions by the polymer backbone.