Nucleophilic substitution

define nucleophile:

• a species with a lone pair of electrons and either a negative charge or an atom with a delta - ( polar) charge ( partially positive )

  • nucleo - positive

  • phile - attracted to

• nucleophiles are attracted to positive or delta positive atoms

the nucleophile ( nuc) uses its lone pair to form a covalent bond

examples:

• water ( H2O)

• ammonia

• OH- ( three lone pairs around oxygen and a fully negative charge on the O)

• nitrile ion

  • Carbon triple bonded to a nitrogen ion - lone pair on carbon atom and full minus charge on carbon atom

C-F, C-Cl, C-Br, C-I

• all of these are polar

• the polar bond in halogenoalkanes means the carbon atom is delta positive and is therefore open to nucleophilic attack.

3H and C and nucleophile + X-