N,N-Diisopropylethylamine, or Hünig’s base, DIPEA or DIEA, is an organic compound and an amine. It is used in organic chemistry as a base. Because the nitrogen atom is shielded by the two isopropyl groups and an ethyl group only a proton is small enough to easily fit. Like 2,2,6,6-tetramethylpiperidine, this compound is a good base but a poor nucleophile, which makes it a useful organic reagent. Hünig’s base is named after the German chemist Siegfried Hünig. The compound is a colourless liquid.
Hünig’s base is commercially available. It is traditionally prepared by the alkylation of diisopropylamine with diethyl sulfate. If necessary, the compound can be purified by distillation from potassium hydroxide.