N,N'-Di-2-butyl-1,4-phenylenediamine

N,N'-Di-2-butyl-1,4-phenylenediamine is an aromatic amine used industrially as an antioxidant to prevent degradation of turbine oils, transformer oils, hydraulic fluids, lubricants, waxes, and greases. It is particularly effective for hydrocarbon products produced by cracking or pyrolysis, which are characterized by high olefin content. It is also used as an inhibitor in production of various vinyl monomers.

It has the appearance of a corrosive red liquid. It is a skin sensitizer and can be absorbed through skin. It is toxic.

It is the active component of eg. AO-22, AO-24, AO-29, and VANLUBE antioxidant mixtures, and Santoflex 44PD inhibitor.