Schiff base equilibria. VIII. Aqueous equilibria between salicylaldehyde and aliphatic diamines

Abstract

Equilibria between salicylaldehyde and three aliphatic diamines, ethylenediamine, trimethylenediamine, and 1,3-diaminopropan-2-ol, have been measured in aqueous solution containing a large excess of diamine to suppress hydrolysis. Equilibrium constants are reported for the formation and acid-base reactions of the mono-salicylideneimines formed from the three diamines. It is demonstrated that there are no conditions under which detectable concentrations of bis- salicylideneimines exist in aqueous solution.