I. A nuclear magnetic resonance study of amidinium ions in solution. II. The kinetics of the thermal decomposition of azobisisobutyramidines and their salts in solution
<p>Part I</p> <p>N. m. r. spectra of unsubstituted and symmetrically substituted aliphatic amidinium salts in dimethyl sulioxide or water demonstrate the presence of hindered internal rotation about the C_(CN)-N bonds in the amidinium groups. The kinetics of nitrogen-proton exc...
| Summary: | <p>Part I</p>
<p>N. m. r. spectra of unsubstituted and symmetrically substituted aliphatic amidinium salts in dimethyl sulioxide or water demonstrate the presence of hindered internal rotation about the C_(CN)-N bonds in the amidinium groups. The kinetics of nitrogen-proton exchange in dilute aqueous add and sulfuric acid-water mixtures, containing amidinium salts, have been studied by the n. m. r. method and compared with proton exchange reactions of ammonium ions in similar media. The nature of the nitrogen-proton magnetic resonance signals of amidinium salts is discussed in terms of current theory concerning the effect of the ^(14)N nucleus on magnetic resonance characteristics of bonded hydrogen atoms.</p>
<p>Part II</p>
<p>Rates of the thermal decomposition of two aliphatic azo-bis-amidines, and their first and second conjugate acids, have been determined. The rate of decomposition of the first and second conjugate acids for each azo-amidine are quite similar, but much greater than those of the corresponding neutral azo-amidines. The efficiencies of radical production of the neutral azo-amidines are only slightly less than those of the second conjugate acids, indicating that the "cage effect" may be only slightly influenced by electrostatic repulsive interactions between geminate radicals. The synthesis of a new aliphatic azo-nitrile is described.</p>
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