Wydział Chemii

Teresa Dziembowska

Z. Rozwadowski

Aleksander Filarowski

Poul Erik Hansen

2001

Magnetic Resonance in Chemistry

39

67-80

10.1002/mrc.949

Naukowa

Angielski

Artykuł

The proton transfer equilibrium in series of Schiff bases derived from 2-hydroxy-1-naphthaldehyde and 1-hydroxy-2-acetonaphthone were measured by means of ¹H, ¹³C and ¹⁵N NMR spectra and deuterium isotope effects on ¹³C and ¹⁵N chemical shifts at variable temperature and in different solvents. The latter made it possible to investigate a broad range of equilibrium positions. All compounds exist mainly as the NH tautomer over the full range of temperatures in CDCl₃ solution. The position of the equilibrium was estimated using ¹J(¹⁵N,¹H) and ³J(¹⁵NH,¹H) coupling constants. The correlation between deuterium isotope effects ⁿΔ¹³C-2(XD) or ⁿΔ¹⁵N(XD), where X = O or N, and the mole fraction of the NH form show the characteristic, non-monotonic function as for other intramolecular hydrogen bonded systems. The position of the minimum depends on substituents and the maximal negative values of ⁿΔ¹³C-2(XD) varies with substituents and solvents.

https://doi.org/10.1002/mrc.949

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