Verteilungseigenschaften von Benzolderivaten. III. Zur Kinetik der diffusionskontrollierten Verteilung von mono- und disubstituierten Benzolderivaten im System n-Octanol/Wasser

Autor: K. Lübeck, Thomas Schelenz, U. Henze, Claus-Rüdiger Kramer
Rok vydání: 1993
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Zdroj: Journal f�r Praktische Chemie/Chemiker-Zeitung. 335:273-278
ISSN: 1521-3897
0941-1216
DOI: 10.1002/prac.19933350310
Popis: Distribution Properties of Benzene Derivatives. III. On the Kinetics of the Diffusion-controlled Distribution of Mono- and Disubstituted Benzene Derivatives in the System n-Octanol/Water The kinetics of the diffusion-controlled distribution of 22 mono- and disubstituted benzenes in the solvent system n-octanol/water were investigated spectrophotometrically in the UV-VIS range at various temperatures between 288 and 333 K. The first-order rate constants k1 and k2 and the activation parameters were determined graphically. In this way, an interesting deviation from theory could be observed in the temperature range from 300 up to 308 K, which is discussed on the basis of known anomalies of water at the interface. Studies on relationships between rate constants (lg k1, lgk2) and hydrophobicity (lgP) show a nearly constancy of k1, while the rate of transport from the organic to the aqueous phase (k2) strongly depends on hydrophobicity described by lgP. The calculated regression equations correspond to analogous relationships found for mechanically influenced distributions and can therefore be explained by the same kinetical model.
Databáze: OpenAIRE
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