A PROTON MAGNETIC RESONANCE INVESTIGATION OF ROTATIONAL ISOMERISM IN 1,1,2,2-TETRACHLORO-1-FLUOROETHANE

1961 ◽  
Vol 39 (1) ◽  
pp. 39-41 ◽  
Author(s):  
R. J. Abraham ◽  
H. J. Bernstein
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Resonance Spectrum ◽  
Rotational Isomerism ◽  
Coupling Constants ◽  
Proton Resonance ◽  
Resonance Investigation ◽  
Magnetic Resonance Investigation

The doublet separation in the proton resonance spectrum of the liquid was measured from −53 to 100 °C. From the variation of the separation with temperature approximate values of the trans and gauche HF coupling constants were obtained. The values of ΔH ≈ 400 cal/mole and ΔS ≈ 0 are also consistent with the data.

Application of Proton Magnetic Resonance to Rotational Isomerism in Halotoluenes. VII. Barriers to Rotation and Conformational Preferences in α,α,α′,α′,2,4,5,6-Octachloro-m-xylene

1971 ◽  
Vol 49 (9) ◽  
pp. 1489-1496 ◽  
Author(s):  
J. Peeling ◽  
B. W. Goodwin ◽  
T. Schaefer ◽  
C. Wong
Keyword(s):  
Magnetic Resonance ◽  
Low Temperatures ◽  
Proton Magnetic Resonance ◽  
Resonance Spectrum ◽  
Activation Parameters ◽  
Rotational Isomerism ◽  
Proton Resonance ◽  
Temperature Dependent ◽  
Conformational Preferences ◽  
Carbon Carbon Bonds

At low temperatures α,α,α′,α′,2,4,5,6-octachloro-m-xylene exists as three conformers in solution and the proton resonance spectrum can be assigned by comparison to the spectrum of α,α,α′,α′,2,4,6-heptachloro-m-xylene. The temperature dependent spectra of the former in toluene-d8 solution are fitted to computed spectra based on a set of coupled Bloch equations. The activation parameters for the rotation about the sp2–sp3 carbon–carbon bonds are Ea = 14.93 ± 0.13 kcal/mol, log A = 12.45 ± 0.09, ΔH≠ = 14.30 ± 0.14 kcal/mol, ΔS≠ = −2.0 ± 0.5 e.u., ΔG≠ = 14.9 ± 0.05 kcal/mol at 298 °K. The quoted errors are standard deviations.

Proton magnetic resonance investigation of the system zinc perchlorate–methanol: evidence for the association of zinc and perchlorate ions

1969 ◽  
Vol 47 (8) ◽  
pp. 1417-1421 ◽  
Author(s):  
S. A. Al-Baldawi ◽  
T. E. Gough
Keyword(s):  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Proton Magnetic Resonance ◽  
Resonance Spectrum ◽  
Solvation Shell ◽  
Proton Magnetic Resonance Spectrum ◽  
Kcal Mole ◽  
Resonance Investigation ◽  
Line Widths ◽  
Magnetic Resonance Investigation

The proton magnetic resonance spectrum of the system zinc perchlorate–methanol is reported for a range of sample concentrations and temperatures. The results are interpreted in terms of association between the zinc and perchlorate ions, and the various features of the spectrum discussed in terms of this interaction. From the temperature-dependence of line-widths, Ea = 14 ± 2 kcal mole−1 and log10A = 16 ± 3 are estimated for the molecular exchange of methanol from the solvation shell of zinc into the bulk solvent.

scholarly journals A proton magnetic resonance investigation of the glycosyl torsion angle of uracil nucleosides and nucleotides

1975 ◽  
Vol 2 (4) ◽  
pp. 459-467 ◽  
Author(s):  
Thomas Schleich ◽  
Ted R. Lusebrink ◽  
Bradford P. Cross ◽  
Neil P. Johnson
Keyword(s):  
Magnetic Resonance ◽  
Torsion Angle ◽  
Proton Magnetic Resonance ◽  
Resonance Investigation ◽  
Magnetic Resonance Investigation

Protonenresonanz-spektroskopische Untersuchungen am Chlor-, Brom- und Methylcyclobutadieneisentricarbonyl / A Proton Magnetic Resonance Investigation on Chloro-, Bromo- and Methyl-cyclobutadiene-irontricarbonyl

1974 ◽  
Vol 29 (3-4) ◽  
pp. 219-227 ◽  
Author(s):  
Hans Albert Brune ◽  
Hans Hanebeck ◽  
Gernot Horlbeck ◽  
Hans Hüther
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Electron Distribution ◽  
Membered Ring ◽  
Bond Orders ◽  
Higher Symmetry ◽  
Resonance Investigation ◽  
Cyclic Diene ◽  
Magnetic Resonance Investigation ◽  
Single Bonds

Proton magnetic resonance spectra including all observable 13C-H-couplings have been measured for chloro-cyclobutadiene-irontricarbonyl.bromo-cyclobutadiene-irontricarbonyl and methyl-cyclobutadiene-irontricarbonyl. The results are discussed with respect to structure and bonding. The structure of a cyclic diene with alternating double and single bonds can be excluded for the four-membered ring of all three compounds. Instead the complex bonded cyclobutadiene contains an electron distribution of higher symmetry with — despite the influence of the substituent — nearly uniform bond orders.

A NUCLEAR MAGNETIC RESONANCE INVESTIGATION OF THE PROTONATION OF AMIDES IN FLUOROSULPHURIC ACID

1963 ◽  
Vol 41 (1) ◽  
pp. 148-155 ◽  
Author(s):  
R. J. Gillespie ◽  
T. Birchall
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nitrogen Atom ◽  
Low Temperatures ◽  
Carbonyl Oxygen ◽  
Proton Resonance ◽  
Resonance Investigation ◽  
Nuclear Magnetic Resonance Investigation ◽  
Peak Areas ◽  
Magnetic Resonance Investigation

The proton resonance spectra of solutions of acetamide, N,N-dimethylacetamide, formamide, and N,N-dimethylformamide in fluorosulphuric acid have been studied at temperatures between 25° and −98°. At low temperatures a new peak appears in the spectra of solutions of all four compounds which is not present at room temperatures and which, from peak areas and other consideration, may be assigned with certainty to the [Formula: see text] group. It is thereby unambiguously established that these amides protonate on the carbonyl oxygen and not on the nitrogen atom.

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