Dibromination

Dibromination is a chemical reaction in which two bromine atoms are added to a molecule. This process typically occurs through an electrophilic addition or substitution reaction. In electrophilic addition, a molecule containing a double or triple bond reacts with a source of electrophilic bromine, such as elemental bromine (Br2). The pi bond in the unsaturated molecule acts as a nucleophile, attacking the electrophilic bromine atom. This forms a cyclic bromonium ion intermediate, which is then attacked by the bromide ion to yield a vicinal dibromide, where the two bromine atoms are attached to adjacent carbon atoms.

Substitution dibromination, on the other hand, involves replacing two hydrogen atoms in a molecule with bromine atoms. This can occur through radical substitution, often initiated by light or heat, or through electrophilic aromatic substitution on highly activated aromatic rings. The conditions and reagents used will determine whether addition or substitution occurs, and the specific positions of the bromine atoms on the product molecule. Dibrominated compounds find applications as intermediates in organic synthesis, flame retardants, and in the production of pesticides and pharmaceuticals.