The pKa values for a series of 12, substituted 2-(N,N-dimethylamino)chromones have been determined by potentiometric titration and found to lie within a narrow range (1.92–2.52), protonation of the carbonyl oxygen being supported by 13C NMR data and semi-empirical and ab initio calculations.
References
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Part 9. KayeP. T., and RamaiteI. D. I., J. Chem. Res. (S), 1997, 414.
2.
CoxJ.S. G., BeachJ. E., BlairA. M. J. N., ClarkeA. J., KingJ., LeeT. B., LovedayD. E. E., MossG. F., OrrT. S. C., RitchieJ. T., and SheardP., Adv. Drug Res., 1970, 5, 115.
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8.
This value is somewhat lower than the value (2.0) reported some time ago, see BrogdenP.J., GabbuttC. D., and HepworthJ. D., in Comprehensive Heterocyclic Chemistry, Vol. 3, Eds. BoultonA.J., and McKillopA., Pergamon, Oxford, 1984, p. 637.
