Electron reorganization induced by intramolecular hydrogen bonding in phenol derivatives: relationship between proton chemical shifts and the hydroxylic electron populations

1986 ◽  
pp. 773 ◽  
Author(s):  
Jean-Paul Seguin ◽  
Fr�d�rique Guillaume-Vilport ◽  
Raoul Uzan ◽  
Jean-Pierre Doucet
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Shifts ◽  
Intramolecular Hydrogen Bonding ◽  
Phenol Derivatives ◽  
Intramolecular Hydrogen ◽  
Proton Chemical Shifts

Hydrogen bonding in sulfanes

1968 ◽  
Vol 46 (22) ◽  
pp. 3587-3590 ◽  
Author(s):  
E. Muller ◽  
J. B. Hyne
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Resonance Spectrum ◽  
Chemical Shifts ◽  
Intramolecular Hydrogen Bonding ◽  
Supporting Evidence ◽  
Absorption Bands ◽  
Hydrogen Bonding Interactions ◽  
Intramolecular Hydrogen ◽  
Proton Chemical Shifts

The position of the proton signals in the nuclear magnetic resonance spectrum of sulfanes (H2Sx) is dependent on the sulfur chain length, the sulfane concentration, and the temperature. These proton chemical shifts are interpreted in terms of sulfane–sulfane interactions and intramolecular hydrogen bonding in sulfanes. Supporting evidence is provided by the position and appearance of the SH-absorption bands of the sulfanes in the infrared, which also establishes the existence of sulfane–solvent interactions.It is concluded that sulfanes participate in hydrogen bonding interactions and it is suggested that there may be a special type of intramolecular hydrogen bonding operative in H2S3.

scholarly journals NMR of Natural Products as Potential Drugs

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3763
Author(s):  
Poul Erik Hansen
Keyword(s):  
Natural Products ◽  
Hydrogen Bonding ◽  
Density Functional ◽  
Chemical Shifts ◽  
Isotope Effects ◽  
Density Functional Theory Calculations ◽  
Intramolecular Hydrogen Bonding ◽  
Chemical Equilibria ◽  
Nmr Techniques ◽  
Intramolecular Hydrogen

This review outlines methods to investigate the structure of natural products with emphasis on intramolecular hydrogen bonding, tautomerism and ionic structures using NMR techniques. The focus is on 1H chemical shifts, isotope effects on chemical shifts and diffusion ordered spectroscopy. In addition, density functional theory calculations are performed to support NMR results. The review demonstrates how hydrogen bonding may lead to specific structures and how chemical equilibria, as well as tautomeric equilibria and ionic structures, can be detected. All these features are important for biological activity and a prerequisite for correct docking experiments and future use as drugs.

A carbon-13 nuclear magnetic resonance study of the basicities of aliphatic alcohols

1987 ◽  
Vol 65 (8) ◽  
pp. 1769-1774 ◽  
Author(s):  
Donald G. Lee ◽  
Kenneth J. Demchuk
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Free Energy ◽  
Hydrogen Bonding ◽  
Chemical Shifts ◽  
Intramolecular Hydrogen Bonding ◽  
Nuclear Magnetic Resonance Study ◽  
Slope Parameter ◽  
Magnetic Resonance Study ◽  
Linear Free Energy ◽  
Intramolecular Hydrogen

Carbon-13 nmr chemical shifts have been used to determine the basicity constants for nine alcohols. The method involves comparing the chemical shifts for carbon atoms adjacent to the site of protonation with those for carbon atoms in a more remote position. The differences in the chemical shifts (Δ values) at different acidities are then used to calculate basicity constants for the alcohols. The pKBH+ values, determined by use of the "X function" are as follows: ethanol −2.12, 1-propanol −2.12, 3-chloro-1-propanol −2.24, 2-chloroethanol −2.45, 2-bromoethanol −2.41, 2-nitroethanol −2.09, 2-methoxyethanol −1.93, 2-phenoxyethanol −1.87, and 2-propanol −2.06. The typical slope parameter, m*, is 0.17. Two linear free energy correlations are obtained: when the alcohols are considered to be a series of monosubstituted ethanols, the Hammett plot has a slope of 0.65; when they are considered to be a series of mono- and disubstituted methanols, the slope is 1.7. Alcohols bearing oxygen-containing substituents are more basic than predicted by about 0.5 pK units, presumably because their conjugate acids can be stabilized by intramolecular hydrogen bonding.

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