Novel route to N-alkyl- and N,N"-dialkylhydrazines by high-pressure alkylation of azines

Reactions of alkyl halides with azines of p-nitrobenzaldehyde, benzaldehyde, and p-methoxybenzaldehyde at a high pressure (10 kbar) were studied. Hydrolysis of the reaction mixtures gives pure N-monoalkyl- or N,N"-dialkylhydrazines in high yields, depending on the structure of the starting azine and the solvent nature. It was found that non-symmetrical N,N"-dialkylhydrazines can be synthesized without isolating intermediate N-monoquaternary immonium salts. The effect of the phase transition of the solvent on the direction of the alkylation is discussed.