Dipole moments of 3- and 4-methylpyridazine N-oxides and their related compounds were measured in order to determine the positions of N→O group in these compounds, and the following conclusions were derived. 1. It was confirmed that IV was 1-oxide and III and V were 2-oxides. 2. In 4-methyl derivatives, VIII and IX are 1-oxides and XI and XII are 2-oxides.
