Studies on Pyridazines. XIV. Syntheses of 3, 3'-Bipyridazines

3-Halogenopyridazines (I) were alloued to react with hydrazine hydrate in the presence of Pd-CaCO3 and alkali to afford the symmetrical 3, 3'-bipyridazines (IIa-IIg). When an equimolar mixture of two kinds of 3-chloropyridazines of different substituents was subjected to this condensation reaction, the unsymmetrical 3, 3'-bipyridazines (VIIa-VIId) were formed. Various 3-chloropyridazine N-oxides (X) were subjected to the condensation reaction and the expected 3, 3'-bipyridazine di-N-oxides (XI) were obtained in low yields.