The substituent effects on the 13C chemical shifts of the azomethine carbon atom of N-(substituted phenyl)salicylaldimines

Abstract

Hammett correlations between the 13C-NMR chemical shifts of the azomethine carbon atom and the corresponding substituent constants were established for thirteen Schiff bases. The successful correlation of the chemical shifts with the electrophilic substituent constants s+ indicate a significant resonance interaction of the substituents on the aniline ring with the azomethine carbon atom in the examined series of imines. The demand for electrons in the investigated compounds was compared to that of the N-benzylideneanilines and N-(substituted phenyl)pyridinealdimines. The manner of transmission of the substituent effects is discussed and they were separated into resonance and inductive effects. The inductive effects prevail over the resonance effects.

13C-NMR hemijska pomeranja 13 Šifovih baza korelisana su sa konstantama supstituenata korišćenjem Hametove jednačine. Dobra korelacija hemijskih pomeranja azometinskog ugljenika sa elektrofilnim konstantama supstituenata (s+) pokazuje da postoji izražena rezonantna interakcija supstituenata na anilinskom prstenu sa azometinskim ugljenikom. Ispitivan je prenos elektronskih efekata supstituenata i oni su razdvojeni na induktivne i rezonantne efekte, a pokazano je da preovlađuju induktivni efekti.