Deuterium Isotope Effect on Shifts of 13C Magnetic Resonance Signals of Sugars: Signal Assignment Studies

1974 ◽  
Vol 52 (3) ◽  
pp. 458-461 ◽  
Author(s):  
Philip A. J. Gorin
Keyword(s):  
Magnetic Resonance ◽  
Isotope Effect ◽  
Chemical Shifts ◽  
Deuterium Isotope Effect ◽  
Signal Assignment

The 13C chemical shifts of nuclei in several sugars undergo an isotope effect 0 to −0.10 p.p.m when a proton in the β position is substituted by a deuteron. The effect may be used for signal assignments in crowded spectra if it is taken into account that lower values are observed for 13C nuclei which are attached to more electronegative groups. The β effect coupled with the elimination of the α-carbon signal have been used to assign signals in c.m.r. spectra of the α- and β-anomers of D-glucose, D-mannose, D-allose, and D-galactose.

Solvent and α-substituent perturbations of the 2H/1H isotope shifts in the 13C nuclear magnetic resonance of toluene-α-d3

1987 ◽  
Vol 65 (3) ◽  
pp. 534-537 ◽  
Author(s):  
Ted Schaefer ◽  
James Peeling ◽  
Rudy Sebastian
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Refractive Index ◽  
Magnetic Resonance ◽  
Isotope Effect ◽  
Electron Donor ◽  
Chemical Shifts ◽  
Aromatic System ◽  
Expectation Value ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr

The 2H/1H isotope effect on 13C nmr chemical shifts, nΔ, n being the number of intervening bonds between 2H and 13C nuclei, in toluene-α-d3 is solvent dependent. For example, 1Δ ranges from 817 ppb in CD3OH to 869 ppb in acetone-d6 solutions, a positive number indicating increased shielding in the deuterated species. 1Δ is linearly dependent on a function of the refractive index, nD, of the solvent, allowing extrapolation to nD = 1. The hyperconjugative model, in which the C—D bond is a poorer electron donor to the aromatic system than is a C—H bond, is tested for the substituents CH2D, CHD2, CD3, CHDCH3, CD2CH3, CD(CH3)2, C6H5CHD, and (C6H5)2CD. For these substituents, the negative 5Δ is linearly related to the expectation value of sin2 θ; θ is the angle by which the C—D bond twists out of the benzene plane. The model fails quantitatively for C6H5CD2X (X = Cl, COOH, CN, OH). For X = OH, very large negative 5Δ and 3Δ values are observed. nΔ is also reported for 4-ethyltoluene-α-d3 and benzaldehyde-α-d1. For the latter, all nΔ values are positive other than 5Δ, which vanishes in acetone-d6 solution.

Studies Based on Deuterium Isotope Effect on13C Chemical Shifts

ChemInform ◽  
2005 ◽  
Vol 36 (3) ◽  
Author(s):  
T. Dziembowska ◽  
P. E. Hansen ◽  
Z. Rozwadowski
Keyword(s):  
Isotope Effect ◽  
Chemical Shifts ◽  
Deuterium Isotope Effect
Sign in / Sign up

Export Citation Format

Share Document