Introduction to Nucleophilic Addition Reactions

When a carbonyl group is attacked by a nucleophile, the carbon atom undergoes a change in hybridization and geometry. 

The electrophilicity of a carbonyl group derives from resonance effects as well as inductive effects  

In general, aldehydes are more reactive than ketones toward nucleophilic attack. This observation can be explained in terms of both steric and electronic effects  

Steric effects. A ketone has two alkyl groups (one on either side of the carbonyl) that contribute to steric hindrance in the transition state of a nucleophilic attack. In contrast, an aldehyde has only one allg l group, so the transition state is less crowded and lower in energy. 

Electronic effeas. Recall that alkyl groups are electron donating. A ketone has two electron-donating alkyl groups that can stabilize the 8+ on the carbon atom of the carbonyl group. In contrast, aldehydes have only one electron-donating group  

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Preparing Aldehydes and Ketones A Review Introduction to Nucleophilic Addition Reactions Oxygen Nucleophiles Nitrogen Nucleophiles Mechanism Strategies Sulfur Nucleophiles Hydrogen Nucleophiles Carbon Nucleophiles Baeyer-Villiger Oxidation of Aldehydes and Ketones Synthesis Strategies... 

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