A Multinuclear Magnetic Resonance Study of Intramolecular Hydrogen Bonding in Some Schiff and Schiff–Mannich Bases in Solution and in the Solid State

2000 ◽  
Vol 18 (1-4) ◽  
pp. 97-105 ◽  
Author(s):  
Wojciech Schilf ◽  
Bohdan Kamieñski ◽  
Anna Szady-Chelmieniecka ◽  
Eugeniusz Grech
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Magnetic Resonance ◽  
Intramolecular Hydrogen Bonding ◽  
Mannich Bases ◽  
Magnetic Resonance Study ◽  
Intramolecular Hydrogen ◽  
Multinuclear Magnetic Resonance

Selective deshielding of aromatic protons in some ortho-substituted acetanilides

1968 ◽  
Vol 46 (15) ◽  
pp. 2593-2600 ◽  
Author(s):  
James R. Bartels-Keith ◽  
Ronald F. W. Cieciuch
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Solvent Effects ◽  
Proton Magnetic Resonance ◽  
Aromatic Proton ◽  
Intramolecular Hydrogen Bonding ◽  
Low Field ◽  
Intramolecular Hydrogen

Certain ortho-substituted acetanilides exhibit proton magnetic resonance signals at unusually low field for the amido proton and the aromatic proton adjacent to the acetamido group. This effect, explicable in terms of intramolecular hydrogen-bonding, has been observed for nitro, carbonyl, sulfamoyl, and sulfonyl substituents. Solvent effects are discussed.

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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