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

Aradi Ferenc | Zendy; Földesi András | Zendy

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

Author(s) -

Aradi Ferenc,

Földesi András

Publication year - 1985

Publication title -

magnetic resonance in chemistry

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.483

H-Index - 72

eISSN - 1097-458X

pISSN - 0749-1581

DOI - 10.1002/mrc.1260230518

Subject(s) - theophylline , chemistry , sodium benzoate , caffeine , sodium salicylate , chemical shift , aqueous solution , sodium , sodium salt , sodium nitrite , theobromine , inorganic chemistry , organic chemistry , pharmacology , biochemistry , medicine , endocrinology

The interaction of caffeine and theophylline with sodium benzoate and sodium salicylate has been studied in deuterium oxide at 35 °C by measuring 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 caffeine‐sodium benzoate, theophylline‐sodium benzoate, caffeine‐sodium salicylate and theophylline‐sodium salicylate were found to be 2.1 ± 0.1, 1.5 ± 0.2, 7.8 ± 0.2 and 5.0 ± 0.21 mol −1 , respectively.

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