Electronic spectra of 2-N-substituted derivatives of 2-amino-4-nitropicolines - I. 2-alkylamino-3- (or -5)-methyl-4-nitropyridine N-oxides

The UV spectra of 2-methyl- and 2-ethylamino-3- (or -5)-methyl-4-nitropyrid ine N-oxides in ethanol have been examined and compared with results (trans ition energies, intensities) of modified INDO calculations in order to make the assignment of allowed bands. The influence of substituents in the mole cule on lambda(max) and epsilon(max) of spectral bands is discussed. The el ectronic spectra of 2-alkylamino-3- (or -5)-methyl-4-nitropyridine N-oxides and the effect of steric hindrance on the spectra are interpreted. The pre paration procedure of four new 2-alkylamino-4-nitropicoline N-oxides is des cribed.