An electrophile is an electron pair acceptor
- Mechanism for the reaction between ethene and Bromine.The halogen adds across the double bond.
balanced equation: C2H4 + Br2 ---->C2H4Br2
Alkenes react in the cold with pure liquid bromine, or with a solution of bromine in an organic solvent like tetrachloromethane. The double bond breaks, and a bromine atom becomes attached to each carbon. The bromine loses its original red-brown colour to give a colourless liquid. In the case of the reaction with ethene, 1,2-dibromoethane is formed.
When Br2 approaches,the Br--Br bond becomes polar. A pair of electrons flow from the double bond to the slightly positive Cl and a bond is formed.
A nucleophile attacks and electron deficient carbon atom of group and donates its electron pair.
halogenoalkanes take part with nucleophiles like (OH-) or H2O
Aqueous Hydroxide ions OH- react with chloromethanein a nucleophilic substitution reaction.
The nucleophilic OH- attacks the back of the carbon atom donating an electron pair. A new bond is formed and the carbon-halogen bond breaks