Protonation of triaminobenzenes in aqueous solution : reactions involving aromatic compounds, σ-complexes and cyanine ions

The protonation of the 1,3,5-triaminobenzenes tripyrrolidinobenzene (TPB), methyltripyrrolidino-benzene (Me-TPB), ethyltripyrrolidinobenzene (Et-TPB), isopropyltripyrrolidinobenzene (Pri-TPB), trimorpholinobenzene (TMB) and tripiperidinobenzene (TPiB) has been studied. Data are reported for rate and equilibrium constants for the formation of σ-complexes (for TPB, TMB, TPiB, Me-TPB and Et-TPB), for equilibrium constants of the competing N-protonation (for TPB, TMB and TPiB) and for rate and equilibrium constants of the further C-protonation of σ-complexes leading to cyanine ions (for TPB, Me-TPB, Et-TPB and Pri-TPB).