Competitive electron impact induced methylene imine elimination from methyl- and dimethylamino N-heterocycles. 1—substituted melamines

Competitive intramolecular expulsion of methylene imine is evaluated for heterocyclic methylamino and dimethylamino substituents using selectively labelled N²,N²,N⁴-trimethylmelamine. In this compound methylene imine expulsion from the dimethylamino group is favored by more than 2:1 over loss from the methylamino group. The effects of other fragmentations and hydrogen randomisation are estimated independently using methylmelamines with each of the groups as the sole source of methylene imine loss.