Equilibrium constants for association of caffeine and theophylline with aromatic salts in aqueous solutions studied by 1H NMR chemical shift measurements

✍ Scribed by Ferenc Aradi; András Földesi

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 333 KB
• Volume: 23
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260230518

✦ Synopsis

The interaction of caffeine and theophylline with sodium benzoate and sodium salicylate has been studied in deuterium oxide at 35°C by measnring the aromatic salt-induced changes in the chemical shifts of the N-methyl protons. Taking into account the self-association of the N-methylxanthines, on the basis of a 1 : 1 complexation model the association constants for caffein-odium benzoate, theophylline-sodium benzoate, deine-sodium salicylate and theophylline-sodium salicylate were-found to be 2.1 0.1, 1.5 f 0.2, 7.8* 0.2 and 5.0 =t 0.2 1 mol-l, respectively.