Reactions of Aldehydes and Ketones

The Nucleophile
Only some of the nucleophiles that react well in nucleophilic substitution at sp3 hybridized carbons give reasonable yields of nucleophilic addition products.
Cl–, Br–, and I– are good nucleophiles in substitution reactions at sp3 hybridized carbons, but they are ineffective nucleophiles in addition. Addition of Cl– to a carbonyl group, for example, would cleave the C – O ? bond, forming an alkoxide. Because Cl– is a much weaker base than alkoxide formed, equilibrium favors the starting materials (the weaker base, Cl–), not the addition product.
The situation is further complicated because some of the initial nucleophilic addition adducts are unstable and undergo elimination to form a stable product
The Nucleophile
Only some of the nucleophiles that react well in nucleophilic substitution at sp3 hybridized carbons give reasonable yields of nucleophilic addition products.
Cl–, Br–, and I– are good nucleophiles in substitution reactions at sp3 hybridized carbons, but they are ineffective nucleophiles in addition. Addition of Cl– to a carbonyl group, for example, would cleave the C – O ? bond, forming an alkoxide. Because Cl– is a much weaker base than alkoxide formed, equilibrium favors the starting materials (the weaker base, Cl–), not the addition product.
The situation is further complicated because some of the initial nucleophilic addition adducts are unstable and undergo elimination to form a stable product
The Nucleophile
Only some of the nucleophiles that react well in nucleophilic substitution at sp3 hybridized carbons give reasonable yields of nucleophilic addition products.
Cl–, Br–, and I– are good nucleophiles in substitution reactions at sp3 hybridized carbons, but they are ineffective nucleophiles in addition. Addition of Cl– to a carbonyl group, for example, would cleave the C – O ? bond, forming an alkoxide. Because Cl– is a much weaker base than alkoxide formed, equilibrium favors the starting materials (the weaker base, Cl–), not the addition product.
The situation is further complicated because some of the initial nucleophilic addition adducts are unstable and undergo elimination to form a stable product