Nucleophilic Addition

NUCLEOPHILIC ADDITION

Nucleophilic addition is an addition reaction where in a chemical compound a π bond is removed by the creation of two new covalent bonds by the addition of a nucleophile.

Addition reactions are limited to chemical compounds that have multiple-bonded atoms such as:

• Carbonyls
• Imines
• Nitriles
• Molecules with carbon double bonds such as Alkenes
• Molecules with carbon triple bonds such as Alkynes

Nucleophilic addition in molecules with carbon-hetero double bonds

Above is an example of a 1,2 nucleophilic addition. The C=O bond is polar (there is a large difference in in electronegativity between the carbon and oxygen) and consequently carbon carries a small positive charge. This makes the carbon atom the primary target for the nucleophile (noted as Nu in the diagram).

Steric factors to be taken into account

• Alkyl groups are bigger than hydrogen
• Ketone carbonyls are less susceptible to nucleophiles.
• Tetrahedral products are more crowded than planar aldehydes or ketones.
• The product from a ketone is more crowded than that from an aldehyde.

Summary

• Alkyl…