[The optimization of the availability of homologous quaternary ammonium compounds. 2. In vitro studies on the partition of homologous benzilic acid esters of dimethyl-(2-hydroxyethyl)-alkylammonium bromides].
The partition of homologous quaternary esters of benzilic acid is studied in a modified three-phase model according to Schulmann (water-n-octanol-water). The logarithms of the partition coefficients of the compounds increase linearly with increasing alkyl chain. The rate determining step for the interphase transport of hydrophilic compound is the diffusion through the organic diffusion layer. The rate constants for the transfer from the aqueous to the organic phase increase linearly with the corresponding partition coefficient, whereas the rate constants for the reverse reaction are not influenced. With increasing chain length the diffusion through the aqueous diffusion layer becomes rate determining for the interphase transport. Thus the rate constants for the transfer from the aqueous to the organic phase are independent of partition coefficients. The rate constants for the reverse transfer are inversely proportional to the corresponding partition coefficients. The half-lives of the transfer of the homologous compounds under sink conditions show a minimum between the heptyl and octyl derivative. The equilibration time decreases with increasing agitation, concentration and temperature. The significance of the results for biological problems is discussed.
D001561:Benzilates; D004058:Diffusion; D006207:Half-Life; D007700:Kinetics; D000442:Octanols; D000644:Quaternary Ammonium Compounds; D013329:Structure-Activity Relationship; D013696:Temperature; D014867:Water
D001561:Benzilates; D000442:Octanols; D000644:Quaternary Ammonium Compounds; D014867:Water
Zur Optimierung der Verfügbarkeit homologer quartärer Ammoniumverbindungen. 2. In-vitro-Versuche zur Verteilung von Benzilsäureestern homologer Dimethyl-(2-hydroxyäthyl)-alkylammoniumbromide