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1H and 13C NMR studies on the self-association of retinoic acid

✍ Scribed by D. Vincent Waterhous; Donald D. Muccio

Publisher: John Wiley and Sons
Year: 1990
Tongue: English
Weight: 417 KB
Volume: 28
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1260280306

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✦ Synopsis

Abstract

The monomer–dimer equilibrium of retinoic acid in carbon tetrachloride was studied by ^1^H and ^13^C NMR spectroscopy. The dimer dissociation constant at 24°C was determined to be 0.38 mM from a fit of the changes in the carboxylic acid carbon chemical shift as a function of concentration. The temperature dependence of the equilibrium constant obtained from the ^13^C NMR signals was used to determine the enthalpy (8.0 kcal mol^−1^) and entropy (12 cal mol^−1^ K^−1^) changes for the dimer dissociation process. These results were shown to be more precise than the values obtained from the carboxylic acid proton resonance.

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