Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10637165 | Solid State Sciences | 2005 | 6 Pages |
Abstract
Layered crystalline barium phenylphosphonate, as anhydrous Ba(HO3PC6H5)2 or hydrated Ba(HO3PC6H5)2â
2H2O compounds, were used as hosts for the intercalation of polar n-alkylamine molecules of the general formula H3C(CH2)nNH2 (n=1 to 5) in ethanol or 1,2-dichloroethane. The lamellar compound was calorimetrically titrated with amine in ethanol or 1,2-dichloroethane solutions at 298.15±0.20K. The exothermic enthalpic values increased with the number of carbon atoms in the amine chain, being â4.50±0.37, â5.30±0.42, â6.77±0.21, â7.51±0.35 and â10.35±0.67kJmolâ1 for hydrated and â6.80±0.22, â7.75±0.37, â8.95±0.19, â9.91±0.34 and â10.82±0.56kJmolâ1 for anhydrous compounds, for n=1 to 5, respectively. The favorable enthalpic processes, as a in function of the number of carbon atoms (nc) of the amines, expressed by ÎHo=â(1.22±0.12)â(1.43±0.16)nc, and ÎHo=â(4.77±0.11)â(1.02±0.02)nc in ethanol and 1,2-dichloroethane, respectively, are more pronounced for the anhydrous compound. The spontaneity of these systems, reflected in the negative Gibbs free energies and the favorable positive entropic values, agrees with the displacement of coordinated solvent molecules as the intercalation takes place.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Angélica M. Lazarin, Ilauro S. Lima, Claudio Airoldi,