| Résumé | The differences in the heats of formation in solution of the stable free radicals, 2,2,6,6-tetramethylpiperid-4-one 1-oxyl (1a), 2,2,6,6-tetramethylpiperdine N-oxyl (1b), and di-tert-butyliminoxy (2), and their hydrogenated precursors have been determined by a direct calorimetric technique. The equilibrium constants for the hydrogen atom transfer reactions of these radicals with certain hydroxylamines and oximes were then determined by the epr spectroscopic method. The analysis of the results of these experiments leads to the predictions that the O-H bond strengths of unhindered dialkylhydroxylamines are in the range of 72-74 kcal/mol while the O-H bond strengths of simple unhindered oximes are equal to approximately 86 kcal/mol. |
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