Synthesis of a series of dichloroamino- and dihalosulfonamido-1,3,5-triazines and investigation of their hindered rotation and stereodynamic behaviour by NMR spectroscopy

Mono-substituted 1,3,5-triazines (s-triazines) have been prepared and characterised by NMR spectroscopy. The room temperature C-13 NMR spectra of dichloroamino-s-triazines show three signals for the triazine ring, clearly indicating that C(2) and C(3) are in inequivalent environments. At elevated temperatures, two of the signals broaden and coalesce. Conversely, a number of dihalosulfonamido-s-triazine compounds were found to display only one signal for C(2) and C(3), indicating that the degree of pi-bonding in the exocyclic C-N bond in these compounds is less significant. The low temperature exchange limits for the dihalosulfonamido-s-triazine compounds are reported.