Spectrophotometric Studies of 3- and 5-Substituted 1-(4′-Dimethylaminobenzylideneamino)-2-methylpyridinium Perchlorates

Abstract

Methyl groups in positions 2 and 6 of pyridine ring shift the long-wavelength band in the spectra of 3-substituted 1-(4′-dimethylaminobenzylideneamino) pyridinium salts towards shorter waves. The intensity of that band depends on nature of the substituent for 2-methyl derivatives, whereas a little hyperchromic effect was observed for the compounds carrying 6-methyl group. Linear dependencies were found between the band parameters and [sgrave] Hammett constants. Substituent effects on the band position in the spectra of 2-methyl-3-substituted compounds were weakened by the methyl groups present. It does not interact sterically with the substituent in position 3 of the pyridine ring.

Key Words:

• 1-(Benzylideneamino)pyridinium salts
• electronic spectra
• steric effect