The preparation and properties of s-triazine are discussed. Nucleophilic reagents (even water) readily attack s-triazine. Thus, open-chain and heterocyclic compounds, e.g. formamidiner, aminomethylene compounds, and triazole, pyridine, and pyrimidine derivatives are accessible froni s-triaiirie. With amidines and imido ethers substituted triazities are obtained (by trans-triazination). The latter are formed via open-chain intermediates.