The partition coefficients, P, between n-octanol and water of carnitine, acetylcarnitine, propionylcarnitine, and tetraethylammonium pentacyanopropenides have been determined spectrophotometrically at 20° C, The value of P increases upon addition of electrolytes, the increase produced by LiCl being particularly high. The carnitine cations are 'salted-out' by electrolytes as shown by the variation of their 'single ion' activity coefficients (relative to that of the tetraethylammonium ion) with electrolyte concentration. These cations are appreciably more hydrated than the reference tetraethylammonium ion. The considered carnitine cations are at least one pKa(where Ka is the acid dissociation constant) unit more acidic than butanoic acid in water at 25 ° C. Electrolyte addition somewhat increases the pKa of these cationic acids.
Effect of the Addition of Electrolytes on the Partition Coefficients, Activity Coefficients, and Acid Dissociation Constants of Carnitine and its Acetyl and Propionyl Derivatives
DE MARIA, Paolo;FONTANA, Antonella;
1994-01-01
Abstract
The partition coefficients, P, between n-octanol and water of carnitine, acetylcarnitine, propionylcarnitine, and tetraethylammonium pentacyanopropenides have been determined spectrophotometrically at 20° C, The value of P increases upon addition of electrolytes, the increase produced by LiCl being particularly high. The carnitine cations are 'salted-out' by electrolytes as shown by the variation of their 'single ion' activity coefficients (relative to that of the tetraethylammonium ion) with electrolyte concentration. These cations are appreciably more hydrated than the reference tetraethylammonium ion. The considered carnitine cations are at least one pKa(where Ka is the acid dissociation constant) unit more acidic than butanoic acid in water at 25 ° C. Electrolyte addition somewhat increases the pKa of these cationic acids.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
