Hydrogen bonding Part 40. IR and thermodynamic study of stability and stoichiometry for triethylenediamine dioxide hydrates, triethylenediamine monohydrate, and a mixed H2O/H2O2 solvate of triethylenediamine dioxide

Abstract

Vapour pressure vs. H2O content studies confirm that triethylenediamine dioxide forms stable crystalline hydrates containing 3,2 or 1 moles H2O per mole of amine dioxide. There is also a pentahydrate which is stable in contact with liquor but effloresces in air to form the trihydrate. Thermodynamic parameters for the dissociations of the tri-, di- and monohydrates were determined through equilibrium vapor pressure measurements; minimum HOHN hydrogen bond strengths in the three hydrates are about 9-10 kcal mol-1. Triethylenediamine dioxide· (H2O)0.67(H2O2)0.33 was prepared by desolvation of a higher mixed solvate, and thermo- dynamic parameters determined for the successive dissociations of H2O2. The IR spectrum of triethylenediamine monohydrate suggests that H2O molecules bridge between nitrogen atoms in adjacent molecules of the base. the role of temperature in defining stoichiometry of hydrate systems is discussed. © 1992.