Kröhnke_oxidation
The Sommelet reaction is an organic reaction in which a benzyl halide is converted to an aldehyde by action of hexamine and water.[1][2] It is named after the French chemist Marcel Sommelet, who first reported the reaction in 1913.[3]
One example, thiophene-2-carboxaldehyde is prepared by the reaction of hexamine with 2-chloromethylthiophene.[4] The reaction is formally an oxidation of the carbon.