Correlation between the pKa and nuclear shielding of α-hydrogen of ketones
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The α-H acidity is an important chemical property of ketones that has attracted much research interest. Theoretical prediction of pKa for ketone α-H is significant. In this work, we theoretically studied the nuclear shielding of various α-Hs in a set of ketones and that of the corresponding enolic hydroxyl Hs in tautomeric enol forms. It has been demonstrated through linear regression analyses that the pKa values of these ketones correlate with both sets of the calculated nuclear shielding values. The correlation coefficient R2 of the linear correlation relationship is 0.90. The present work has provided a new approach to computationally evaluating the acidity of α-Hs in ketones, enabling us to semi-empirically predict the ketone α-H acidity from the calculated nuclear shielding values.
KeywordsNuclear shielding pKa Ketone Enol Linear correlation
The work was supported by the National Natural Science Foundation of China (grant number 21273089), the Fundamental Research Funds for the South-Central University for Nationalities (CZW17004), the Open Project Fund of the Key Laboratory of the Pesticides and Chemical Biology of Central China Normal University (grant number 2018-A01).
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