Process for preparing hydrazine hydrate with pyrazoline recycling

A process for preparing hydrazine hydrate, comprising the following steps:

• (a) reacting ammonia, hydrogen peroxide and methyl ethyl ketone in the presence of a solution comprising at least one activator to form an azine;
• (b) treating the reaction mixture from step (a) to isolate:
• an aqueous phase comprising the at least one activator;
• and
• an organic phase comprising the azine and optionally unreacted methyl ethyl ketone;
• (c) optionally recycling the aqueous phase to step (a) after optional treatment;
• (d) washing the organic phase;
• (e) distilling the washed organic phase to recover the azine;
• (f) hydrolyzing the azine to give hydrazine hydrate and regenerated methyl ethyl ketone, with pyrazoline-class heterocycles being purged;
• (g) optionally recycling the methyl ethyl ketone obtained in step (f) to step (a);
• and
• (h) recycling the pyrazoline-class heterocycles purge obtained in step (f) to one at least of steps (a), (b), (c), (d) or (g).