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Deuterium isotope effect on 13C NMR spectra of ortho Mannich bases.
Autorzy
Rok wydania
1995
Czasopismo
Numer woluminu
67
Strony
63-69
DOI
10.1016/0167-7322(95)00866-7
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
The deuterium isotope effect upon 13C NMR spectra was studied for ortho Mannich bases of varying ΔpKa value [ΔpKa = pKa(NH+) − pKa(OH)]. The Δ values [Δ = δ13C(OH) − δ13C(OD)] for different positions in the phenyl ring are consistent with calculations of charge distribution by means of MNDO — PM3 method and assuming that deuteration leads to a weakening of the hydrogen bonding. In the critical range of ΔpKa, where the proton transfer appears, the inversion of the sign of the isotope effect for the carbon atom in position 1 takes place. Strong dependence of the Δ value on temperature was revealed for 2-(N,N-diethylaminomethyl)-3,4,5,6-tetrachlorophenol showing the proton transfer equilibrium.
Adres publiczny
https://doi.org/10.1016/0167-7322(95)00866-7
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