Presentation Transcript
Electrophilic Addition of Bromine to Ethene :Electrophilic Addition of Bromine to Ethene
Step 1: Polarization of Br2 by C=C :Step 1: Polarization of Br2 by C=C As the bromine approaches the ethene molecule, its electron density is repelled away from the C=C, setting up a temporary dipole.
Step 2: Electrophilic attack by C=C :Step 2: Electrophilic attack by C=C The ? bond of the C=C bond breaks and the ? electrons form a bond with the ?+ bromine atom.
Step 3: Addition of Br- ion to intermediate :Step 3: Addition of Br- ion to intermediate The bromide ion is attracted to the positively charged bromonium ion. A
Step 4: Addition of Br- ion to intermediate :Step 4: Addition of Br- ion to intermediate The bromide ion forms a C–Br bond. It is evident that UV light is not essential to initiate the reaction. The reaction is initiated by a electrophilic attack by bromine.