Studies of chemical exchange by nuclear magnetic resonance methods
| Autor: | L. W. Reeves, P. T. Inglefield, R. Stewart, E. Krakower |
|---|---|
| Rok vydání: | 1968 |
| Předmět: |
Coupling constant
Cyclohexane Chemistry Methyl nitrite Biophysics Condensed Matter Physics Spectral line chemistry.chemical_compound Reaction rate constant Nuclear magnetic resonance Intramolecular force Molecule Physical and Theoretical Chemistry Atomic physics Molecular Biology Shape analysis (digital geometry) |
| Zdroj: | Molecular Physics. 15:65-86 |
| ISSN: | 1362-3028 0026-8976 |
| DOI: | 10.1080/00268976800100821 |
| Popis: | Several hindered internal rotation barriers have been re-examined using both spin-echo Carr-Purcell measurements and complete fits of the line shapes developed in high resolution N.M.R. spectra. Significant errors in our present work and previous studies are found and their origin is discussed. At the present time, the spin-echo method tends to give rate constants which are too high in the slow exchange region and too low in the fast exchange region compared to complete line shape analysis of high resolution spectra. The activation energies are approximately 10 to 15 per cent too low. The possibility of measuring the relative signs of coupling constants from line shapes when the exchanging nuclei are both coupled to a third nucleus in an intramolecular exchange process is discussed. The molecules studied here include methyl nitrite, N,N-dimethylformamide, N,N-dimethylcarbamyl chloride and cyclohexane. In the case of the measurement of rates of exchange for methyl groups in N,N-dimethylformamide by high re... |
| Databáze: | OpenAIRE |
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