Kinetic study of the thermal dehydration of copper(II) dipicolinates: Crystal and molecular structure of Cu(II) (pyridine 2,6-dicarboxylato) DI- and trihydrated
As a basis for the description of dehydration mechanisms, the molecular structures of two copper(II) dipicolinates, Cu(dipic).2H2O (triclinic) and Cu(dipic).3H2O, are presented and compared with those of other copper(II) dipicolinates. The kinetics of the isothermal dehydration of the monoclinic and...
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| Autores principales: | , , , |
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| Formato: | JOUR |
| Materias: | |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00223697_v58_n7_p1127_Sileo |
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| Sumario: | As a basis for the description of dehydration mechanisms, the molecular structures of two copper(II) dipicolinates, Cu(dipic).2H2O (triclinic) and Cu(dipic).3H2O, are presented and compared with those of other copper(II) dipicolinates. The kinetics of the isothermal dehydration of the monoclinic and triclinic polymorphs of Cu(dipic).2H2O were measured. The monoclinic variety dehydrates in a two-step process; a linear α/t relationship is found for the first step and a two-dimensional diffusion-controlled reaction (D2) law ((1 - α) 1n(1 - α) + α = kt) for the second. Triclinic Cu(dipic).2H2O dehydrates in a one-step process, The relation between a and time is linear at lower temperatures but gradually changes to an Avrami-Erofe'ev (A2) model (-1n(1 - α)1/n = kt) at higher temperatures. A qualitative model based on optical microscopic observations, structural determinations and thermogravimetric data is proposed. The general relationship between dehydration behavior and structure in this series of compounds is discussed. © 1997 Elsevier Science Ltd. All rights reserved. |
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