paranitroaniline

Paranitroaniline, commonly known as p-nitroaniline or 4-nitroaniline, is an aromatic nitro compound used as an intermediate in the dye and pharmaceutical industries. Its molecular formula is C6H6N2O2 and its molecular weight is about 138.12 g/mol. The molecule contains a benzene ring with two substituents in para positions: an amino group and a nitro group.

It appears as a pale yellow to colorless crystalline solid and has a melting point around 147–149 °C. It is poorly soluble in water but dissolves in many organic solvents such as ethanol and acetone. The nitro group strongly withdraws electrons, making the compound less basic than aniline.

Synthesis typically involves the nitration of aniline, which yields a mixture of ortho- and para-nitroaniline; the para isomer is separated by crystallization or chromatography. In industry, p-nitroaniline serves as a versatile precursor for dyes and pigments. It can be reduced to p-phenylenediamine, a common azo-dye intermediate used in diazo coupling reactions.

Safety and handling: p-nitroaniline is toxic and can irritate the skin, eyes, and respiratory tract. It may be harmful if swallowed or inhaled. It should be handled with appropriate personal protective equipment in a well-ventilated area and stored in a cool, dry place away from oxidizers.