No abstract

The barrier to rotation about the a mido C-N bond has been measured for five C-substituted N, 'dime thylamides. Dimethylcarbamyl chloride has been extensively studied previously, and a critical survey of the systematic errors in all determinations has been achieved by a composite plot of the derived parameters A6f* vs. AS *.

S~~c l e a r shielding parameters have been obtained for 24 intramolecularly hydrogen-bonded pheiiols and naphthols. The shielding parameters are corrected for large diamagnetic anisotropies and a value Auon obtained which represents the change in shielding parameter in parts per million with reference to the infinite dilution chemical shift of phenol, a-naphthol, or 0-naphthol. These val~les of Auon are approximately proportional to the change Avon in the OH stretching frequency on forniation of the hydrogen bond.

The app1ication of a recent multi-site chemicaJ exchange formulation of the Bloch equations is made to an intramolecular and an intermolecular process. The experimental precautions to achieve a good complete line shape fit are discussed in some detail.The exclusive exchange groups and providing Iine positions and intensities are known with the line width in the absence of exchange, the whole spectrum can be reproduced using only 2-site rate matrix elements. Representative experimental and computed spectra are presented. The relationship of the matrix elements to chemical rate constants is derived but determinations of these constants are not yet complete.

ConclusionElectrode processes with specific adsorption of reactant and/or product can be analyzed rather rigorously by the method of this paper. Further progress requires experimental studies on (a) adsorption isotherms, (b) 591 determination of the standard free energy of adsorption as a function of charge density, and (c) application of the experimental criterion deduced in this paper.Acknowledgment.-This investigation was supported by the National Science Foundation.