n-alkylmonoamine into crystalline lamellar titanium phenylphosphonate

Abstract

Crystalline lamellar titanium phenylphosphonate was intercalated with n-alkylmonoamines, H₃C(CH₂)_n-NH₂ (n=0 to 3), which decomposed on heating in four distinct stages. The lamellar compound was calorimetrically titrated with ethanolic amine solution at 298.15±0.02 K and the enthalpy, Gibbs free energy and entropy were calculated. with the exception of butylamine, the enthalpic values increased with the number of carbon atoms in the amine chain, as -16.20±0.22; -18.70±0.19; -23.70±0.24 and -18.30±0.22 kj mol^-1, from n=0 to 3. The exothermic enthalpic values reflected a favorable energetic process of intercalation, when the solvated ethanol molecules on inorganic matrix are progressively substituted by solute. The negative gibbs free energy results supported the spontaneity of the reactions and the positive favorable entropic values are in agreement with the increase of solvent molecules in the reaction medium, as the amine becomes bonded to the crystalline lamellar inorganic matrix.