Chemistry Reference
In-Depth Information
Oxygen is more electronegative than nitrogen. As such, oxygen holds its lone pairs of
electrons more tightly than does nitrogen. Therefore, the most nucleophilic site is
Ammonium ions, having no available electron pairs, are not nucleophilic.
Carboxylate anions are nucleophilic, but the anions are stabilized through delocaliza-
tion of the negative charge, thus decreasing their nucleophilicity. As mentioned in
Problem 2(b), nitrogen is less electronegative than oxygen. As the only oxygen
atoms in this compound are associated with a stable carboxylate anion, the most
nucleophilic site is
This structure represents an acyl anion with the negative charge delocalized to the
oxygen. Since the carbon and the oxygen both possess partial negative charge charac-
teristics, the degree of nucleophilicity depends upon the relative electronegativities of
carbon versus oxygen. Since oxygen is more electronegative than carbon, the most
nucleophilic site is
3. For each molecule, show the partial charges, bond polarity, and where a nucleophile is
most likely to react.
