SUBSTITUENT EFFECTS IN HYDROXAMATE NUCLEOPHILE DISPLACEMENTS AT CARBONYL CENTERS.
DELAWARE UNIV NEWARK DEPT OF CHEMISTRY
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The charge effect previously discussed for nucleophilic displacements on isopropyl methylphosphonofluoridate by non-alpha but not by alpha nucleophiles was investigated in analogous reactions occurring at carbonyl centers. The catalytic coefficients determined for a variety of neutral and cationic para substituted benzohydroxamates in reaction with both p-nitrophenylbenzoate and p-nitrophenyl-p-nitrobenzoate were plotted in both Bronsted and Hammett linear free energy relationships. These and other data appear to be consistent with the conclusion that the charge effect is a reflection of the differences in the mechanism of charge dispersal in the respective transition states for alpha and non-alpha nucleophiles engaged in nucleophilic attack at unsaturated centers. Author
- Organic Chemistry
- Physical Chemistry