Rate processes, nuclear magnetic resonance

Gutowsky H S and Holm C H 1956 Rate processes and nuclear magnetic resonance spectra. II. Hindered internal rotation of amides J. Chem. Phys. 25 1228-34... 

Binsch, G., The Study of Intramolecular Rate Processes by Dynamic Nuclear Magnetic Resonance, 3, 97. 

Nuclear Magnetic Resonance, for Study of Intra-Molecular Rate Processes (Binsch) 3 97... 

Nuclear magnetic resonance (NMR) spectroscopy is a most effective and significant method for observing the structure and dynamics of polymer chains both in solution and in the solid state [1]. Undoubtedly the widest application of NMR spectroscopy is in the field of structure determination. The identification of certain atoms or groups in a molecule as well as their position relative to each other can be obtained by one-, two-, and three-dimensional NMR. Of importance to polymerization of vinyl monomers is the orientation of each vinyl monomer unit to the growing chain tacticity. The time scale involved in NMR measurements makes it possible to study certain rate processes, including chemical reaction rates. Other applications are isomerism, internal relaxation, conformational analysis, and tautomerism. 

Nuclear magnetic resonance spectra may be so simple as to have only a single absorption peak, but they also can be much more complex than the spectrum of Figure 9-23. However, it is important to recognize that no matter how complex an nmr spectrum appears to be, it involves just three parameters chemical shifts, spin-spin splittings, and kinetic (reaction-rate) processes. We shall have more to say about each of these later. First, let us try to establish the relationship of nmr spectroscopy to some of the other forms of spectroscopy we already have discussed in this chapter. 

The development of nuclear magnetic resonance spectroscopy for the measurement of the rates of fast reactions (preexchange lifetimes 1-0.001 second) has made it possible to study many alkyl-metal exchange processes which heretofore were experimentally inaccessible. A substantial number of papers dealing with the exchange reactions of Group I, II, and III... 

To draw conclusions concerning the templating effect of different molecules, comparable conditions for the crystallization process must be used. In this paper we present a systematic investigation on the effect of mono-, di- and tri-n-alkylamine and tetraalkylammonium compounds (alkyl = C. - C,) upon the rate of crystallization, yield and the properties of the products. Also the field of a template-free synthesis is studied. The products were characterized by magic-angle-spinning nuclear magnetic resonance spectroscopy (MAS NMR) and X-ray diffraction. 

This chapter describes preparation of Si02 thin film by the sol-gel method using photoirradiation and the effect of heat treatment on the molecular structure of the Si02 in the film examined using Raman and nuclear magnetic resonance (NMR) spectroscopy. The relationships between the molecular characteristics and physical properties such as hardness and etch rate are derived, and applications for the new process are described. 

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