Their double bond is an area of high electron density and therefore is an area of high negative charge. This charge is able to induce a dipole on an electrophile, giving it a slightly positive and slightly negative charge. Due to these charges, the slightly negative end of the electrophile will attack the positive C=C bond.
Electrophile: An electron-deficient species which will readily accept a lone pair of electrons
The electrophile will accept the pair of electrons from the double bond, which breaks the alkene C=C bond and produces a carbocation whilst one of the atoms in the electrophile takes on the electrons from the bond, causing the other to become a nucleophile ion.
Carbocation: An organic ion with a positively charged carbon atom
the remaining nucleophile will then form a dative covalent bond with the carbocation to form a halogenalkane, this is due to the lone pair of electrons in the nucleophile being attracted to the postive carbon.
Stability of carbocations:
When an electrophile attackes and alkene with 3+ carbon atoms, a mix of products are formed due to the alkene being unsymmetrical.
- Unequal amounts of each product are formed due to the relative stabilities of the carboncation intermediates
More stable products (tertiary carbocarbons) are produced in higher quantities to those that are less stable (primary carbocations).
Examples of electrophillic addition reactions:
1. Unsaturated hydrocarbons (Bromine test)
- When bromine…