Ionisation constants of heterocyclic substances. Part VIII. 1,3,5-Triazaindenes

Abstract

Syntheses are described for seven new chloro-, hydroxy-, mercapto-, and methylthio-1,3,5-triazaindenes with these substituents in the 2-, 6-, and 2,6-positions, and also for their methyl derivatives. Methylation of 2-methyl-thio-1,3,5-triazaindene gives a mixture of the N-1, N-3, and N-5 monomethyl derivatives, the structures of which are established by unambiguous syntheses. 6-Chloro-1,3,5-triazaindene similarly gives three products, two of which have been identified as the N-1 and N-3 monomethyl derivatives. The effects of substituents and the position of protonation on the ionisation constants and ultraviolet spectra are discussed.