Synthesis,
characterization and thermal studies on solid compounds of 2-chlorobenzylidenepyruvate
of heavier trivalent lanthanides and yttrium(III) |
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Authors: | G Bannach E Schnitzler O Treu
Filho V H S Utuni M Ionashiro |
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Institution: | (1) Instituto de Química UNESP, Araraquara, Brazil, CP 355, CEP 14801-970, SP;(2) Departamento de Química, UEPG, Ponta Grossa, Brasil, 84030-000 , PR |
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Abstract: | Solid-state
compounds of general formula LnL3⋅nH2O,
where Ln represents heavier lanthanides
and yttrium and L is 2-chlorobenzylidenepyruvate,
have been synthesized. Chemical analysis, simultaneous thermogravimetry-differential
analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry,
elemental analysis and infrared spectroscopy have been employed to characterize
and to study the thermal behaviour of these compounds in dynamic air atmosphere.
On heating these compounds
decompose in four (Gd, Tb, Ho to Lu, Y) or five (Eu, Dy) steps. They lose
the hydration water in the first step and the thermal decomposition of the
anhydrous compounds up to 1200°C occurs with the formation of the respective
oxide, Tb4O7 and Ln2O3
(Ln=Eu, Gd, Dy to Lu and Y) as final residue.
The dehydration enthalpies found for these compounds (Eu, to Lu and Y) were:
65.77, 55.63, 86.89, 121.65, 99.80, 109.59, 131.02, 119.78, 205.46 and 83.11
kJ mol-1, respectively. |
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Keywords: | benzylidenepyruvate rare earth thermal behaviour |
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