The benzilic acid rearrangement is the rearrangement reaction of benzil with potassium hydroxide to benzilic acid. First performed by Justus Liebig in 1838 this reaction type is displayed by 1,2-diketones in general. The reaction product is an α-hydroxy-carboxylic acid.
Certain acyloins also rearrange in this fashion.
This diketone reaction is related to other rearrangements: the corresponding keto-aldehyde (one alkyl group replaced by hydrogen) rearranges in a Cannizzaro reaction, the corresponding 1,2-diol reacts in a pinacol rearrangement.
Read more about Benzilic Acid Rearrangement: Reaction Mechanism, Variations