Nucleophilic Addition

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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

(http://upload.wikimedia.org/wikipedia/commons/thumb/c/c4/NucleophilicAdditionsToCarbonyls.svg/300px-NucleophilicAdditionsToCarbonyls.svg.png)

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…

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