Name: Conversion
Uploaded: 2019-07-19
Duration: 8 min 3 s
Description: Let's see how nucleophilic substitution takes place in a lab. How can you make it happen? Why does it happen? You'll learn and see and will be stunned beyond...

Question

Explain the mechanism of $S_{N} 2$ reaction with example.

Accepted Answer

$S_{N} 2$ reaction follows second order kinetics and the rate of reaction depends upon both haloalkane and participating nucleophile. Hence, this reaction is known as substitution nucleophilic bimolecular reaction. In this reaction, the nucleophile attacks the positively charged carbon and the halogen leaves the group. It is a one-step reaction. Both the formation of carbocation and exiting of halogen take place simultaneously.

So opposite to the $S_{N} 1$ reaction mechanism, this is favoured mostly by primary carbon, then secondary carbon and then tertiary carbon.

$S_{N} 2$ reaction of an optically active haloalkane is always accompanied by inversion of configuration at the asymmetric centre. Let us consider the following example:
When $2$ -Bromooctane is heated with sodium hydroxide, $2$ -octanol is formed with inversion of configuration. When ( $-$ )- $2$ -Bromo octane is heated with sodium hydroxide, ( $+$ )- $2$ -Octanol is formed, in which $- OH$ group occupies a position opposite to what bromine had occupied.

Where,

(a) = ( $-$ )- $2$ - Bromo octane
(b) = Transition State
(c) = ( $+$ )- $2$ -Octanol (product)

Explain the mechanism of $S_{N} 2$ reaction with example.

Important Questions on Haloalkanes and Haloarenes

Learn and Prepare for any exam you want !

Explain the mechanism of SN2 reaction with example.

Important Questions on Haloalkanes and Haloarenes

Learn and Prepare for any exam you want !

Explain the mechanism of $S_{N} 2$ reaction with example.