Correlation of substituted aromatic β-diketones' characteristic protons chemical shifts with Hammett substituent constants
Article first published online: 23 AUG 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Magnetic Resonance in Chemistry
Volume 51, Issue 11, pages 689–694, November 2013
How to Cite
Zawadiak, J. and Mrzyczek, M. (2013), Correlation of substituted aromatic β-diketones' characteristic protons chemical shifts with Hammett substituent constants. Magn. Reson. Chem., 51: 689–694. doi: 10.1002/mrc.4001
- Issue published online: 4 OCT 2013
- Article first published online: 23 AUG 2013
- Manuscript Revised: 23 JUL 2013
- Manuscript Accepted: 23 JUL 2013
- Manuscript Received: 6 MAY 2013
- Hammett substituent constants;
Influence of dibenzoylmethane's substituents in meta and para positions on chemical shift values of tautomers' characteristic protons was investigated in four solvents with 1H NMR spectroscopy: acetone-d6, benzene-d6, CDCl3 and deuterated dimethyl sulfoxide (DMSO-d6). It was proved that the influence of substituents on chemical shifts strongly depends on the kind of the solvent; the greatest changes were observed in benzene-d6 and the smallest in CDCl3. In acetone-d6 and DMSO-d6, the influence of substituents on chemical shifts is similar and the most regular. It allowed a fair correlation of chemical shifts of para-substituted dibenzoylmethane derivatives' characteristic protons with Hammett substituent constants in these solvents. In CDCl3, characteristic protons' chemical shifts were near 1H NMR spectroscopy measurement error limits, and, therefore, correlation with Hammett substituent constants in this solvent was unsatisfactory. In benzene, although the changes of chemical shifts are the most evident, the changes are also the most irregular, and, therefore, correlation in this solvent failed completely. Results of meta-substituted derivatives were much more irregular, and their correlation with Hammett substituent constants was poor in all investigated solvents. Copyright © 2013 John Wiley & Sons, Ltd.