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|Type:||Artigo de periódico|
|Title:||Crystalline Calcium Phenylphosphonate - Thermodynamic Data On N-akylmonoamine Intercalations|
|Abstract:||Lamellar crystalline calcium phenylphosphonate, as anhydrous Ca(HO3PC6H5)2 and hydrated Ca(HO3PC6H5)2· 2H2O compounds, were used as hosts for intercalation of polar n-alkylmonoamine molecules of the general formula CH3(CH2)nNH2 (n = 0-4, 7) in water or 1,2-dichloroethane. An increase in the interlayer distance was observed. The exothermic enthalpic values for intercalation increased with the number of carbon atoms and with increasing concentration of the amines. The intercalation followed by a titration procedure in the solid/liquid interface with Ca(HO3PC6H5)2· 2H2O and Ca(HO3PC6H5)2 gave the enthalpy/number of carbons correlations: ΔintH = -(1.74 ± 0.43)-(1.30 ± 0.13)nc and Δint H = -(4.15 ± 0.15)-(1.07 ± 0.03)nc, for water and 1,2-dichloroethane, respectively. A similar correlation ΔintH = -(4.27 ± 0.80)-(1.85 ± 0.21)nc was obtained in water by using the ampoule breaking procedure for Ca(HO3PC6H5)2· 2H2O. The increase in exothermic enthalpic values with the increase in n-aliphatic carbon atoms is more pronounced for the anhydrous compound and also when using the ampoule breaking procedure. The Gibbs free energies are negative. Positive entropic values favor intercalation in these systems. © 2002 Elsevier Science B.V. All rights reserved.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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