The Staudinger reaction or Staudinger reduction is a chemical reaction in which the combination of an azide with a phosphine or phosphite produces an iminophosphorane intermediate. Combined with the hydrolysis of the aza-ylide to produce a phosphine oxide and an amine, this reaction is a mild method of reducing an azide to an amine. Triphenylphosphine is commonly used as the reducing agent, yielding triphenylphosphine oxide as the side product in addition to the amine.