Alkenes + Mechanisms

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Electrophilic Addition:

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

(http://www.kshitij-iitjee.com/Study/Chemistry/Part2/Chapter2/8.jpg)

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…

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