Abstract
Reaction of 3-methoxypyridazine with hydrogen peroxide in glacial acetic acid afforded a mono-N-oxide compound (I). On being treated with phosphoryl chloride, (I) yielded 3-methoxy-6-chloropyridazine (II), whose identification by admixture with an authentic specimen proved (I) to be the 1-oxide (Ia). (I) was hydrolyzed to 3-hydroxy-pyridazien 1-oxide (V). Methylation of (V) afforded the original base (I) as the main product and the reaction of (V) with acetic anhydride yielded maleic acid hydrazide (VI). From the consideration of ultraviolet spectrum and pKa values, it was concluded that the phenolic structure (Vc) has a larger contribution than the tautomeric pyridazone N-oxide structure (Vd).
