Sublimation/volatilisation kinetics of 8-hydroxyquinolines and their nitro-derivatives
Nenhuma Miniatura disponível
Data
2001-01-01
Autores
Crespi, Marisa Spirandeli [UNESP]
Zorel, H. E.
Ribeiro, Clovis Augusto [UNESP]
Costalonga, AGC
Torres, C.
Título da Revista
ISSN da Revista
Título de Volume
Editor
Kluwer Academic Publ
Resumo
5-Nitro-8-hydroxyquinoline (B) and 5,7-dinitro-8-hydroxyquinoline (C) were obtained from nitration of 8-hydroxyquinoline (A) and purified in acetone medium and under heating in which the formation of (B) or (C) depends on the amount of HNO3 added. TG curves present mass loss in only one step before and after the melting point (T-m=76 degreesC (A) and 180 degreesC (B)) in different proportions as a function of the heating rate, characterising the sublimation and the volatilisation processes, respectively. The thermal stability of the compounds follow the order: A (77 degreesC)<B (121 degreesC)<C (222 degreesC). Kinetic parameters through TG curves, dynamic process, using heating rates of 1, 2.5, 5, 10 and 20 degreesC min(-1), enabled to obtain the following increasing order to the activation energy values of the compounds: 80.4 (A), 102.0 (B) and 153.9 kJ mol(-1) (C). Other kinetic parameters as pre-exponential and half-lifetime were also estimated.
Descrição
Palavras-chave
8-hydroxyquinoline, kinetic parameters, sublimation, thermogravimetry, volatilisation
Como citar
Journal of Thermal Analysis and Calorimetry. Dordrecht: Kluwer Academic Publ, v. 64, n. 2, p. 783-787, 2001.