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Subject: search.filters.subject.Nuclear Magnetic Resonance

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    Phase Structure, Nuclear Magnetic Resonance and Rheological Properties of Viscoelastic Sodium Dodecyl Sulphate and Trimethylammonium Bromide Mixtures
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Barker, Christopher A.; Saul, Dorothy; Tiddy, Gordon J. T.; Wheeler, Barbara A.; Willis, Edwin
    The phase diagram of octyltrimethylammonium bromide and sodium dodecyl sulphate (SDS) in water (>90 %) is reported at 298 K; the phase regions observed are liquid, two liquid, and liquid plus liquid crystal. Liquids with viscoelastic properties occur close to the SDS rich liquid boundary, and a correlation is observed between the surfactant n.m.r. linewidths and the rheological properties of these liquids. The most likely explanation of these effects is one involving the occurrence of both cylindrical and spherical micelles, but the possibility that the viscoelasticity is due to the presence of a microemulsion can not be excluded.
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    Molecular Complexes: Part 12- Use of Phase Distribution and Nuclear Magnetic Resonance Methods to Elucidate the Mechanism of the Acetone + Benzene Reaction
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Homer, John; Cooke, Melvyn C.
    The results of studies of the acetone+benzene interaction obtained from a phase distribution technique and the conventional n.m.r. approach are compared. This reveals that the conventional n.m.r. approach to studies of molecular complexes can be misleading. In resolving the inherent problems a mechanism for the acetone + benzene reaction is proposed. The reaction is studied in the presence of carbon tetrachloride and cyclohexane separately. It is shown that whereas carbon tetrachloride is reactive towards benzene, cyclohexane is less so and that data obtained by both experimental techniques using this material as solvent provide values for the equilibrium quotient, Kx, and aromatic induced shift, Ac, which are in good agreement.
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    Protolysis Kinetics of some Amino-acids Studied by the Nuclear Magnetic Resonance Spin Echo Technique
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (2), 1973) Eley, D. D.; Fawcett, A. S.; Hey, M. J.
    Proton magnetic relaxation times have been measured as a function of pH and temperature for aqueous solutions of amino-acids in the series H3[graphic omitted]—[CH2]n—CO2 where n= 1, 2, 3, 5 and 7 and also for solutions of α-alanine, sarcosine, L-proline, picolinic acid and 2-pyrrolidone. The T1 values were independent of pH but T2 had a minimum value near to pH 6 at room temperature for most of the solutions studied. In many cases, a second minimum occurred close to pKal for the amino-acid. The data are analysed in terms of proton exchanges between amino groups and sites which are oxygen attached. Kinetic parameters are derived for some exchange reactions which have not previously been considered in connection with amino-acid solutions.