Carbon-13 nuclear magnetic resonance studies of organotellurium compounds. II. Chemical shift trends

1982 ◽  
Vol 60 (5) ◽  
pp. 596-600 ◽  
Author(s):  
Raj. K. Chadha ◽  
Jack M. Miller
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Magnetic Resonance Studies ◽  
Nmr Chemical Shifts ◽  
Organic Group ◽  
Opposite Trend ◽  
Organotellurium Compounds ◽  
C Nmr

13C nmr chemical shifts are reported for some aromatic and aliphatic tellurium compounds. For a given organic group, the shift of the C1 atom varies in the order [Formula: see text], as expected from electronegative considerations. The C2 atom experiences an opposite trend while the C3 and C4 atoms of the ring experience smaller changes. The chemical shifts of para-substituted aromatic tellurium compounds do not show additivity of contributions from the substituents.

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 stereochemical investigation of substituted ethylene sulfites via 13C nuclear magnetic resonance

1976 ◽  
Vol 54 (9) ◽  
pp. 1428-1432 ◽  
Author(s):  
Gerald W. Buchanan ◽  
Desmond G. Hellier
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Conformational Analysis ◽  
Sulfur Atom ◽  
Chemical Shifts ◽  
Nmr Chemical Shifts ◽  
13C Nuclear Magnetic Resonance ◽  
Ethylene Sulfite ◽  
C Nmr ◽  
Nuclear Magnetic

13C nmr chemical shifts for ethylene sulfite and 17 derivatives are presented. From the magnitudes of the γ shifts and the tenets of conformational analysis, support is gained for the existence of twist-envelope conformations in solution. Pseudorotational paths are suggested which do not involve inversion at the sulfur atom.

Improving the accuracy of solid-state nuclear magnetic resonance chemical shift prediction with a simple molecular correction

2019 ◽  
Vol 21 (27) ◽  
pp. 14992-15000 ◽  
Author(s):  
Martin Dračínský ◽  
Pablo Unzueta ◽  
Gregory J. O. Beran
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Chemical Shifts ◽  
Chemical Shift Prediction ◽  
Nmr Chemical Shifts ◽  
Nuclear Magnetic

A simple molecular correction improves significantly the accuracy of predictions of solid-state NMR chemical shifts.

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.

Metabolites of bird's nest fungi. Part 10. Carbon-13 nuclear magnetic resonance studies on the cyathins

1978 ◽  
Vol 56 (16) ◽  
pp. 2197-2199 ◽  
Author(s):  
William A. Ayer ◽  
Thomas T. Nakashima ◽  
Dale E. Ward
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Magnetic Resonance Studies ◽  
Chemical Shift Data ◽  
Related Compounds ◽  
Shift Data ◽  
Methyl Acetal ◽  
Magnetic Resonance Spectra

The carbon-13 magnetic resonance spectra of cyathin A3 and several related compounds have been measured and the chemical shifts have been assigned. The chemical shift data have been used to determine the stereochemistry at C-1 in cyafrin A4 and to determine the position of the bromine in 1-bromoallocyathin A3 methyl acetal.

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.

NUCLEAR MAGNETIC RESONANCE STUDIES: IX. THE CHEMICAL SHIFT OF THE FORMYL PROTON IN ALIPHATIC ALDEHYDES

1966 ◽  
Vol 44 (1) ◽  
pp. 45-51 ◽  
Author(s):  
R. E. Klinck ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Aliphatic Aldehydes ◽  
Magnetic Resonance Studies ◽  
Unsaturated Aldehydes ◽  
Potential Use ◽  
Nuclear Magnetic

The effects of structure on the shielding of formyl protons of aliphatic aldehydes have been examined. The survey included examples of acyclic, alicyclic, and α, β-unsaturated aldehydes. The potential use of these results as an aid for structural elucidations is discussed, and the limitations are noted.

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.

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