Contribution of Substituents to the Distribution Coefficient of NBenzoylNphenylhydroxylamine Derivatives
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Abstract
The distribution coefficient (<i>K</i><sub>D</sub>) for twenty kinds of <i>N</i>benzoyl<i>N</i>phenylhydroxylamine (BPHA) derivatives between chloroform or benzene and the aqueous phase was determined. A linear correlation was obtained between log <i>K</i><sub>D</sub> and the number of carbon atoms containing substituent groups for a series of alkyloxy derivatives. However, the data for those having a series of alkyloxy groups, and others having a straight or branched alkyl chain, fall on two independent lines in plots of log <i>K</i><sub>D</sub> vs. the van der Waals volume of the BPHA derivatives. From these results, the empirical contribution values (π<sub>x</sub>), defined asπ<sub>x</sub>=log <i>K</i><sub>D</sub>(X)log <i>K</i><sub>D</sub>(H) {<i>K</i><sub>D</sub>(H) is the distribution coefficient of a parent compound and <i>K</i><sub>D</sub>(X) that of a derivative}, of the functional group to the distribution coefficient (log <i>K</i><sub>D</sub>), were as follows: 0.54 in a chloroform/ water system and 0.49 in a benzene/water system for the methyl and methylene groups, 0.30 in a chloroform/water system and 0.27 in a benzene/water system for the methoxy group, and 0.23 in a chloroform/water system and 0.12 in a benzene/water system for the nitro group, respectively. The utility of the contribution values (π<sub>x</sub>) for the methyl, methylene, methoxy and nitro groups was verified for estimating the distribution coefficient (<i>K</i><sub>D</sub>) of the BPHA derivatives.
Journal

 Analytical Sciences

Analytical Sciences 11(5), 723728, 19951010
The Japan Society for Analytical Chemistry