A study of the rates of hindered internal rotation
about the C—N bond in N,N-dimethyltrifluoroacetamide
and N,N-dimethyldeuteroformamide has been made using the nuclear magnetic resonance spin echo method. A 40 Mc/sec. spin echo spectrometer, which enables measurements to be made of the transverse relaxation time (T₂) from a Carr Purcell sequence of radio-frequency pulses, is described and its performance illustrated. The precision of values obtained is estimated to be of the order of 5%.
Equations, derived from a theory developed by Bloom, Reeves and Wells for the dependence of
T₂, measured in a Carr Purcell experiment, on pulse intervals in the presence
of a suitable exchange process, have been used to extract the kinetic data for the two molecules. The chemical
shift, rate constant and natural relaxation time (T2₀) have been calculated from the data by curve fitting procedures
using computer techniques, and the experimental verification
of the theory has been noted.
The accuracy of the rate constants and activation parameters
derived is discussed in the light of previous steady state nuclear magnetic resonance studies. The relative merits
of the spin echo and steady state methods are examined
and the possibility of the occurrence of systematic errors in such studies is investigated.
Steady state studies of the proton exchange between methanol and two phenols (meta-cresol and ortho-hydroxyaceto-phenone) and of the ring inversion of N,N-dimethylpiperazine are also presented and the relative merits of the kinetic
parameters discussed. / Science, Faculty of / Chemistry, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/37839 |
| Date | January 1966 |
| Creators | Inglefield, Paul T. |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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