Name: SN2 Reaction
Uploaded: 2019-07-19
Duration: 1 min 59 s
Description: In the SN2 reaction, nucleophiles attack from the back side of the carbon. So the product assumes a stereochemical position opposite to the leaving group.

Question

Distinguish between

S_{N} 1

and

S_{N} 2

mechanism of substitution reaction.

Accepted Answer

$S_{N} 1$ reaction: This reaction is called substitution nucleophilic unimolecular reaction because only one molecule is involved in determining the rate of the reaction. It is a two-step reaction. In the first step, The carbon-halogen bond breaks heterolytically with the halogen retaining the previously shared pair of electrons. In the second step, the nucleophile reacts rapidly with the carbocation that was formed in the first step. Such type of reactions are carried out in polar protic solvents such as water, alcohol, acetic acid etc. Reactivity of alkyl halides towards $S_{N} 1$ reaction is $3 ° > 2 ° > 1 °$ . In this process, racemisation is observed.

$S_{N} 2$ reaction: This 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. This type of reaction occurs in one step through the formation of a transition state. Both the formation of carbocation and exiting of halogen take place simultaneously. In this process, the inversion of configuration is observed. Reactivity of alkyl halides towards $S_{N} 2$ reaction is ${CH}_{3} X > 1 ° > 2 ° > 3 °$ .

Distinguish between $S_{N} 1$ and $S_{N} 2$ mechanism of substitution reaction.

Important Questions on Halogen Derivatives

Learn and Prepare for any exam you want !

Distinguish between SN1 and SN2 mechanism of substitution reaction.

Important Questions on Halogen Derivatives

Learn and Prepare for any exam you want !

Distinguish between $S_{N} 1$ and $S_{N} 2$ mechanism of substitution reaction.