EAS-Halogenation

Halogenation

Bromination

The overall reaction is as follows.

In bromination reactions, the electrophile (Br+) is generated by the interaction of the Br2 with the FeBr3 Lewis acid.

The mechanism proceeds by the same addition/elimination pathway we just discussed.

Chlorination

Chlorination is similar to bromination.  The overall mechanism and generation of the electrophile are analogous to bromination.

Iodination

The overall reaction for iodination is as follows.

Iodination uses slightly different conditions to generate the electrophile.  A REDOX reaction between the Cu+2 and Iodine (I) atom yields Cu+1 and I+.  The electrophile is an I+ species. This reaction is rather slow and low yielding so diazonium salts are often used as precursors to aryl Iodides and fluorides.