Protons spinning

The proton-proton spin couplings (Thh) have been measured for a large number of thiazole derivatives. The results are shown in Tables 1-35 and 1-36. 

It now appears that such difficulties can largely be overcome by the application of proton-proton spin-decoupling and especially by means of the very high resolution now available in spectrometers of the superconducting solenoid type (see below). 

Most 13C spectra are run on Fourier-transform NMR (FT-NMR) spectrometers using broadband decoupling of proton spins so that each chemically distinct carbon shows a single unsplit resonance line. As with NMR, the chemical shift of each 13C signal provides information about a carbon s chemical environment in the sample. In addition, the number of protons attached to each carbon can be determined using the DEPT-NMR technique. 

Noncquivalent protons, spin-spin splitting and, 465-466 tree diagram of, 466 Nootkatone, structure of, 293 Norbornane, molecular model of,... 

The transfer of magnetization from the proton spins to the carbon spins occurs now when the Hartmann-Hahn condition, Eq. (2), is fulfilled. 

Beckmann P. A., Bloom M., Ozier I. Proton spin relaxation in dilute methane gas a symmetrized theory and its experimental verification, Can. J. Phys. 54, 1712-27 (1976). 

PROTON SPIN-LATTICE RELAXATION RATES IN THE STRUCTURAL ANALYSIS OF CARBOHYDRATE MOLECULES... 

The proton spin-lattice relaxation-rate (R,) is a well established, nuclear magnetic resonance (n.m.r.) parameter for structural, configurational, and conformational analysis of organic molecules in solution. " As yet, however, its utility has received little attention in the field of carbohydrate chemistry,... 

AMX, this is possible, because there are three nonselective relaxation-rate values for three unknown py values (pam. Pax, Pmx)- For a system in which y > 3 proton spins, this analysis cannot be unambiguously applied, because there are j(j — )/2 values of py to be determined from j measured R (ns) values. However, under favorable circumstances (see Section IV), depending on the relative disposition of the proton spins in the molecular frame, some Py values may be disregarded. This affords a good estimate of the appropriate Py values, and, hence, information about molecular geometry and conformation. 

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