Carbonyl compounds undergo nucleophilic addition because of:
Correct answer: B. Electronegativity difference and pi bond
- A. More stable anion with negative charge on oxygen and less stable carbocation
- B. Electronegativity difference and pi bond
- C. Electronegative character of carbonyl carbon
- D. None of these
Explanation
Option B is correct because carbonyl compounds undergo nucleophilic addition due to the presence of the polarized carbon-oxygen double bond and the electronegativity difference between carbon and oxygen, resulting in the partial positive charge on the carbonyl carbon. The pi bond in the carbon-oxygen double bond is relatively polarized due to the higher electronegativity of oxygen compared to carbon. This creates a region of positive charge on the carbon atom and a region of negative charge on the oxygen atom. Nucleophilic addition occurs because the nucleophile is attracted to the partially positive carbon atom, which is the electrophilic center due to its lower electron density caused by the electronegative oxygen atom. The nucleophile donates its electron pair to the carbon atom, breaking the pi bond and forming a new bond.
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About Aldehydes and Ketones
Aldehydes and ketones contain the polar carbonyl group, but aldehydes are generally more readily oxidised and more reactive than ketones. Coverage includes preparation by oxidation or reduction routes, nucleophilic addition of reagents such as hydrogen cyanide and bisulfite, and tests that distinguish aldehydes from ketones.
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