Beckmann rearrangement in the solid state: reaction of oxime hydrochlorides

Several ketoxime hydrochlorides undergo Beckmann rearrangement upon heating below their melting points for 5–48 h, in excellent yields (generally >70%). The absence of a reaction solvent and of by-products (except for HCl) makes for a very simple work-up. Aldoxime hydrochlorides apparently undergo dehydration to the corresponding nitriles under the above conditions. Dibenzyl ketoxime hydrochloride unexpectedly furnished a pyrazine derivative (67%), presumably via further reaction of the intermediate nitrilium ion in the crystal lattice.