Triazine chemistry VIII. 2,5‐dihydro‐5‐oxo‐1,2,4‐triazines

Abstract 2,5‐Dihydro‐5‐oxo‐1,2,4‐triazine and some of its alkylated derivatives have been prepared. Nmr spectroscopic analysis has established that the 2,5‐dihydro‐5‐oxo tautomers are preferred over the 4,5‐dihydro‐5‐oxo ones. This preference, and the behavior of 1,2,4‐triazines in some other chemical reactions has been interpreted in terms of electron‐electron repulsions between the lone pairs of electrons of N1 and N2 in this ring system.