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.

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.

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.

13C Nuclear Magnetic Resonance of Oximes. I. Solvent and Isotope Effects on the 13C Chemical Shifts of Acetoxime

1972 ◽  
Vol 50 (12) ◽  
pp. 1956-1958 ◽  
Author(s):  
N. Gurudata
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Solvent Effects ◽  
Chemical Shifts ◽  
Isotope Effects ◽  
Solvent Interactions ◽  
13C Chemical Shifts ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

The 13C n.m.r. spectrum of acetoxime has been obtained in five representative solvents and the chemical shifts of the three carbon atoms measured. The solvent effects on the chemical shifts are found to reflect specific solute–solvent interactions. The effect of deuteration of the α-protons on the chemical shift of the oximino carbon is also discussed.

Nuclear magnetic resonance studies. XI. Vinyl proton chemical shifts and coupling constants of some substituted styrenes

1967 ◽  
Vol 45 (7) ◽  
pp. 731-737 ◽  
Author(s):  
Gurudata ◽  
J. B. Stothers ◽  
J. D. Talman
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Spin Systems ◽  
Coupling Constants ◽  
Vinyl Proton ◽  
Magnetic Resonance Studies ◽  
Vinyl Carbon ◽  
Proton Chemical Shifts ◽  
Nuclear Magnetic

The proton spectra of the vinyl groups in a series of 23 substituted styrenes have been analyzed as ABC spin systems. The proton chemical shifts are compared with the previously reported shielding data for the corresponding vinyl carbon nuclei. The series includes 12 meta- and para-substituted examples and 10 ortho-substituted examples. The effects of steric inhibition of conjugation on the vinyl proton parameters for some 2,6-disubstituted derivatives are considered in detail.

NUCLEAR MAGNETIC RESONANCE STUDIES: VIII. DETERMINATION OF THE THERMODYNAMIC PARAMETERS GOVERNING ASSOCIATIONS OF SUBSTITUTED BENZALDEHYDES IN TOLUENE SOLUTION

1966 ◽  
Vol 44 (1) ◽  
pp. 37-44 ◽  
Author(s):  
R. E. Klinck ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Chemical Shifts ◽  
Toluene Solution ◽  
Kcal Mole ◽  
Magnetic Resonance Studies ◽  
Substituted Benzaldehydes ◽  
Proton Chemical Shifts

The temperature dependence of the proton chemical shifts of four substituted benzaldehydes in toluene solution has been measured. From these results, estimates have been made of the enthalpies and entropies of formation of the stereospecific solute–solvent complexes which were previously shown to exist in these systems. These calculations indicate that the ΔH and ΔS values are −0.9 ± 0.2 kcal/mole and −4.9 ± 1.3 e.u., respectively. No correlation with substitution is apparent; the results are compared with other available data.

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.

Nuclear Magnetic Resonance Chemical Shifts of some Monosubstituted Isothiazoles

1975 ◽  
Vol 53 (4) ◽  
pp. 596-603 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Thomas R. Clem ◽  
Edwin D. Becker
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Charge Densities ◽  
Monosubstituted Benzenes ◽  
Proton Chemical Shifts ◽  
Nuclear Magnetic

Carbon-13 and proton chemical shifts have been measured for several monosubstituted isothiazoles. Substituent effects upon these chemical shifts are compared with those observed for monosubstituted benzenes, pyridines, and thiophenes. In general the observed substituent effects in the isothiazoles and thiophenes closely parallel one another. Correlations between the observed carbon-13 Chemical shifts and CNDO/2 calculated charge densities are examined.

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