Studies on Pyrazine Derivatives. IV. Coupling Constants and Chemical Shifts in Disubstituted Pyrazines

Abstract

The nuclear magnetic resonance parameter of disubstituted pyrazines have been correlated with the chemical structure. The coupling constants of 2, 3-, 2, 5-, 2, 6-disubstituted pyrazines are 2.5-3.0, 1.1-1.4, 0 Hz respectively, and these values are not influenced by the kind of the substituents. The calculated chemical shifts which are obtained from the additivity rule of the shielding parameter of the substituents are well agreed with the observed ones.