Metil e fenilfosfonatos de calcio-sintese, caracterização, intercalação de aminas alifaticas e calorimetria

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

Calcium phosphonates Ca(HO3PR)2.xH2O (x = 1 or 2 R = CH3 or C6H5) were synthesized through reaction in aqueous media between calcium and phosphonic acids. The aim was to intercalate n-alkylamines: methyl -, ethyl -, propyl -, butyl -, pentyl and octylamines into Ca(HO3PC6H5)2.2H2O (CaPP1), Ca(HO3PCH3)2.H2O (CaPM) in aqueous media and the anhydrous Ca(HO3PC6H5)2 compound (CaPP) in 1,2-dichloroethane to yield Ca(HO3PR)2.{2-x)H2O(x)H2N(CH2)nCH3 (n = 0 to 4 and 7 and R = methyl- or phenyl-). Calcium phenylphosphonate was also prepared by topotactic exchange between calcium phosphate and phenylphosphonic acid . The lamellar exfoliation of calcium phosphate was done using concentrated tetrabutylamonium hydroxide solution. The characterization was made through X-ray diffraction pattern, infrared spectroscopy, thermogravimetry, P and C NMR, elementar analysis, surface area and calorimetry using titration and ampoule breaking. Interlamellar distances for CaPP1 and CaPP compounds increased with the length of the aliphatic chain or due to the increase in amine concentration, which behaviour was not observed for CaPM .Thermogravimetric results showed the loss of water, phenyl or methyl groups in the second step and finally to give the residue Ca2P2O7. The intercalate compounds showed an amine loss in an intermediary stage. The enthalpy of reaction obtained through calorimetric titration and by ampoule breaking increases with the length of the aliphatic chain or with the amine concentration for CaPP1 and CaPP1 but not for CaPM.

ASSUNTO(S)

aminas calcio calorimetria

ACESSO AO ARTIGO

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