Pinnick–Lindgren oxidation (sometimes Pinnick oxidation or Lindgren oxidation or similar) is an organic reaction by which aldehydes can be oxidized into their corresponding carboxylic acids using sodium chlorite (NaClO2) under mild acidic conditions. It was originally developed by Bengt O. Lindgren and Nilsson. The typical reaction conditions used today were developed by G. A. Kraus. H.W. Pinnick later demonstrated that these conditions could be applied to oxidize α,β-unsaturated aldehydes. There exist many different reactions to oxidize aldehydes, but only a few are amenable to a broad range of functional groups. The Pinnick oxidation has proven to be both tolerant of sensitive functionalities and capable of reacting with sterically hindered groups. This reaction is especially useful for oxidizing α,β-unsaturated aldehydes, and another one of its advantages is its relatively low cost.General reaction scheme for Pinnick oxidation