Journal of Chemical Thermodynamics, Vol.43, No.1, 69-74, 2011
Thermochemical data for n-alkylmonoamines functionalization into lamellar silicate Al-kanemite
Al-kanemite was synthesized by using inorganic salts as a source for silicon and aluminum in the hydrothermal synthesis of the material The resulting solid was used as hosts for functionalization of polar n-alkylamine molecules of the general formula H3C(CH2),-NH2 (n = 1 to 5) in aqueous solution The compound was calorimetrically titrated with amine in 1 2-dichloroethane requiring three independent operations (i) titration of matrix with amine (ii) matrix salvation and (iii) dilution of the amine solution From those thermal effects the variation in enthalpy was calculated as (-6 81 -7 76 -8 97 -9 94 and -11 83) kJ mol(-1) for n = 1 to 5 respectively The exothermic enthalpy values reflected a favorable energetic process of amine-host functionalization in 1 2-dichloroethane The original and modified Al kanemite samples were characterized by elemental analysis scanning electron microscopic (SEM) and nuclear magnetic nuclei of silicon 29 and carbon-13 The negative Gibbs free energy results supported the spontaneity of all these functionalization reactions The positive favorable entropic values as carbon chain size increased are in agreement with the free solvent molecules in the solution as the amines are progressively bonded to the crystalline inorganic matrix at the solid/liquid interface (C) 2010 Published by Elsevier Ltd