NUCLEAR MAGNETIC RESONANCE STUDIES: PART II. SOLVENT EFFECTS IN THE N.M.R. SPECTRA OF AROMATIC ALDEHYDES

1962 ◽  
Vol 40 (12) ◽  
pp. 2329-2338 ◽  
Author(s):  
R. E. Klinck ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Electron Distribution ◽  
Chemical Shifts ◽  
Aromatic Aldehydes ◽  
Solvent Interaction ◽  
Solvent Interactions ◽  
Magnetic Resonance Studies ◽  
Substituent Group ◽  
Solvent Shift ◽  
Solute Solvent Interaction

The chemical shifts for the aromatic and formyl protons of a series of substituted benzaldehydes have been obtained in a number of solvents. Relative to the shifts observed in chloroform, pronounced effects are observed in acetone and benzene solutions. In general, the shielding of these nuclei is decreased in acetone and increased in benzene, while in benzene the magnitude of the solvent shift for a given proton depends markedly on the nature of the substituent group. These results can be rationalized in terms of a specific solute-solvent interaction in which the site of association is governed by the electron distribution in the solute molecule. The nature of the solvent interactions in this and related systems is discussed.

Nuclear Magnetic Resonance Studies of Solute–Solvent Interactions. Improved Methods of Proton Chemical Shift Determinations for Completely Associated and Unassociated Solutes

1973 ◽  
Vol 51 (5) ◽  
pp. 787-791 ◽  
Author(s):  
R. E. Klinck
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Solvent Ratio ◽  
Proton Chemical Shift ◽  
Solvent Interactions ◽  
Magnetic Resonance Studies ◽  
Improved Methods ◽  
Proton Chemical Shifts

Previous data for the temperature dependence of the proton chemical shifts of two para-substituted benzaldehydes in toluene solution are re-investigated using improved methods for obtaining the proton chemical shifts in the associated and unassociated solutes. The calculations provide ΔH and ΔS values of −1.13 ± 0.07 kcal/mol and −4.0 ± 0.3 e.u., respectively. Attempts to determine the solute–solvent ratio gave inconclusive results.

Studies of specifically fluorinated carbohydrates. Part I. Nuclear magnetic resonance studies of hexopyranosyl fluoride derivatives

1969 ◽  
Vol 47 (1) ◽  
pp. 1-17 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville ◽  
N. S. Bhacca
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Angular Dependence ◽  
Chemical Shifts ◽  
Relative Orientation ◽  
Coupling Constants ◽  
Pyranose Ring ◽  
Spectral Parameters ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

A detailed study has been made of both the 1H and 19F nuclear magnetic resonance (n.m.r.) spectra of a series of hexopyranosyl fluoride derivatives. Some of the 1H spectra were measured at 220 MHz. The 1H spectral parameters define both the configuration and the conformation of each of these derivatives. Study of the 19F n.m.r. parameters revealed several stereospecific dependencies. The 19F chemical shifts depend upon, (a) the orientation of the fluorine substituent with respect to the pyranose ring and, (b) the relative orientation of other substituents attached to the ring; for acetoxy substituents, these configurational dependencies appear to be additive. The vicinal19F–1H coupling constants exhibit a marked angular dependence for which Jtrans = ca. 24 Hz whilst Jgauche = 1.0 to 1.5 Hz for [Formula: see text] and 7.5 to 12.6 Hz for [Formula: see text] The geminal19F–1H couplings depend on the orientation of the substituent at C-2; when this substituent is equatorial JF,H is ca. 53.5 Hz and when it is axial the value is ca. 49 Hz.

Studies of specifically fluorinated carbohydrates. Part II. Nuclear magnetic resonance studies of pentopyranosyl fluoride derivatives

1969 ◽  
Vol 47 (1) ◽  
pp. 19-30 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Resonance Spectroscopy ◽  
Magnetic Resonance Studies ◽  
Conformational Model ◽  
Nuclear Magnetic

Detailed studies, by 1H and 19F nuclear magnetic resonance spectroscopy, of a series of fully esterified pentopyranosyl fluorides, show that all such derivatives favor that conformer in which the fluorine substituent is axially oriented. This conclusion is supported by separate considerations of the vicinal and geminal19F–1H and 1H–1H coupling constants, of the long-range (4J) 1H–1H and 19F–1H coupling constants and of the 19F chemical shifts. The limitations of the above conformational model are discussed.

29Si-Kernresonanzuntersuchungen an N-Trimethylsilyl-substituierten Aminen und Amiden / 29Si Nuclear Magnetic Resonance Studies on N-Trimethylsilyl Derivatives of Amines and Amides

1977 ◽  
Vol 32 (2) ◽  
pp. 163-166 ◽  
Author(s):  
B. Heinz ◽  
H. C. Marsmann ◽  
U. Niemann
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Aromatic Amines ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electronic Charge ◽  
Magnetic Resonance Studies ◽  
Basic Character ◽  
Silyl Derivatives ◽  
Trimethylsilyl Derivatives ◽  
Derivatives Of

The 29Si chemical shifts of several trimethyl silyl derivatives of amines and amides are measured and compared to other chemical and theoretical properties such as the basicities or the electronic charge on the nitrogen or the hydrogen of the N-H group of the amine or the amide. Whereas the 29Si chemical shift of saturated amines can be rationalized in terms of substituent effects, the shifts of aromatic amines show some dependency on the basic character of the amine. There seems to be little correlation between 29Si chemical shifts and electronic charge, but there is a similarity of 29Si with 1H chemical shifts of the NH group, which is interpreted as depending on anisotropy effects.

17O Nuclear Magnetic Resonance Studies in Water of Different Isotopic Composition

1977 ◽  
Vol 32 (2) ◽  
pp. 131-133 ◽  
Author(s):  
O. Lutz ◽  
H. Oehler
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Chemical Shifts ◽  
Deuterium Oxide ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Deuterium Isotope Effect ◽  
Nmr Studies ◽  
Hydrogen Ion Concentration ◽  
Magnetic Resonance Studies ◽  
Made In

17O and 2H Fourier transform NMR studies have been made in water with varying contents of hydrogen isotopes. Chemical shifts of 17O as a function of 2H contents and as a function of the hydrogen ion concentration are given. The ratios of the Larmor frequencies of 17O and 2H in water are used for evaluation of a magnetic moment of 17O in water. The deuterium isotope effect on the 17O NMR line in water is (3.08 ±0.20) ppm to lower frequency for deuterium oxide. No 17O shift was found in deuterium oxide with high 18O enrichment

Nuclear magnetic resonance studies. III. Rotational isomerism of some C-glucosylflavonoid acetates

1965 ◽  
Vol 18 (5) ◽  
pp. 715 ◽  
Author(s):  
RA Eade ◽  
WE Hillis ◽  
DHS Horn ◽  
JJH Simes
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Steric Hindrance ◽  
Chemical Shifts ◽  
Rotational Isomerism ◽  
Bulky Substituent ◽  
Temperature Dependent ◽  
Magnetic Resonance Studies ◽  
Rotational Isomers ◽  
Nuclear Magnetic

The temperature-dependent variations in the spectra of certain C-glucosyl-flavonoid acetates are attributed to the effect of steric hindrance of bulky substituent groups of the sugar and aromatic moieties on the rate of interconversion of the two rotational isomers present. The differences in the chemical shifts of the protons of the two isomers are attributed to differences in the orientation and position of the acetyl and phenyl groups.

Carbon-13 Nuclear Magnetic Resonance Studies of Some Methyl Substituted Diphenylmethanes

1974 ◽  
Vol 52 (18) ◽  
pp. 3196-3200 ◽  
Author(s):  
Gerald W. Buchanan ◽  
Giorgio Montaudo ◽  
Paolo Finocchiaro
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Ring Current ◽  
Chemical Shifts ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

Carbon-13 n.m.r. chemical shifts are reported for diphenylmethane and nine methylated derivatives. Results are compared with those for related methylbenzenes. In the case of tri-ortho-substituted materials the predominance of a perpendicular conformation is suggested. Ring current calculations show that in contrast to the 1H chemical shift interpretations, the 13C shielding trends cannot originate primarily from anisotropic effects.

A Study of Solvent Effects on the 13C Nuclear Magnetic Resonance Spectra of Cholesterol, Pyridine, And Uridine

1973 ◽  
Vol 51 (9) ◽  
pp. 1384-1391 ◽  
Author(s):  
H. H. Mantsch ◽  
Ian C. P. Smith
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Solvent Effects ◽  
Chemical Shifts ◽  
Dipole Interaction ◽  
Simple Relation ◽  
The Other ◽  
Solvent Interaction ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance

The 13C n.m.r. chemical shifts for cholesterol in five solvents are reported. All carbon atoms were subject to solvent effects of varying sign and magnitude. The chemical shifts in the solvent pair dioxane–chloroform 1:1 could be predicted on an additivity basis. Pyridine was studied in 24 solvents; the chemical shifts of all carbons were solvent-dependent. Solvent effects at positions β and γ were correlated, while those at position α bore no simple relation to those of the other carbons. A small isotope effect was noted on comparing the data for H2O and 2H2O. Coupling between 13C and 14N was observed in some cases; its magnitude was solvent-dependent. Uridine was studied in four solvents. While all carbons were subject to solvent-induced shifts, evidence for specific solvent interaction at C-4, -5, -1′, and -2′ was obtained. An appreciable contribution to the relaxation of carbonyl C-2 and -4 from dipole–dipole interaction with the hydrogen on N-3 was observed. Solvent effects can result in scrambling and misassignment of 13C resonances if care is not taken with choice of solvent.

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