This compound can be prepared by two related ways: 1) The reaction of ethyl (2-hydroxypropyl)amine (A) with 3,6-dichloropyridazine (I) in refluxing toluene gives 3-chloro-6-[ethyl(2-hydroxypropyl)amino]pyridazine (II). This intermediate is then reacted with ethyl hydrazinecarboxylate (B) to afford (III). 2) Alternatively, compound (II) may be treated with hydrazine hydrate to afford the hydrazinopyridazine (IV); acylation of (IV) with ethoxycarbonyl chloride provides the final compound (III).