Using the Benzil Rearrangement Reaction To Detect Cyanide

Significance

The authors report the isolation of the mandelonitrile benzoate derivative 5 as the product of the benzil rearrangement reaction of 1 run in an aprotic solvent (i.e., acetonitrile, trichloromethane, or ethyl acetate). In the product 5, the conjugation pathway between the two aryl carbonyl groups originally present in 1 is severed causing a large hypso­chromic shift (Δ λ_max = 56 nm). This effect was exploited by using 1 as a cyanide indicator.