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|Type:||Artigo de periódico|
|Title:||Synthesis, characterization and thermodynamics of the reaction of calcium methylphosphonate with n-alkylmonoamines|
|Abstract:||Lamellar crystalline calcium methylphosphonate, Ca[(HO)O2PCH3](2).H2O reacted with a series of n-monoalkylamines to yield the compounds Ca[(HO)O2PCH3](2). xH(2)N(CH2)(n)CH3. (1-x)H2O (n=0-4). Intense hands of the phosphonate group in the 1095-995 cm(-1) region in the infrared spectrum were detected. X-ray diffraction patterns showed a sharp and intense peak with an interlamellar distance of 907 pm. P-31 NMR spectrum gave a peak at 27.38 ppm for phosphonate groups. On heating methylphosphonate water molecules, organic moiety and P2O5 were released to yield a residue of pyrophosphate. The aminated compound presented the same sequence of mass loss, with amine being lost in the first stage. C-3 NMR spectrum presented peaks at:15 and 17 ppm for methylphosphonate groups. The original crystallinity of the compound is disturbed by the reaction with the n-alkylmonoamine, giving constant interlamellar distance. The energetic effect caused by amine was determined through. reaction-solution calorimetry in the solid-liquid interface from aqueous solution. The thermodynamic data showed that the system is favored by enthalpy, Gibbs free energy, and entropy values. (C) 2001 Elsevier Science Ltd. All rights reserved.|
|Editor:||Elsevier Sci Ltd|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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