Class 12 Chemistry Haloalkanes and Haloarenes SN1 mechanism

SN1 mechanism

The tertiary alkyl halides react by SN1 mechanism via formation of carbocation as intermediate. The reactivity order for SN1 reaction is

Benzyl > Allyl > 3̊ > 2̊ > 1̊ > CH3X.


A mechanism for the reaction of tert-butyl chloride with water apparently involves two steps:


Stereochemistry of SN1:



Key features:

More stable will be the carbocation intermediate; faster will be the SN1 mechanism.

Polar solvents lead to polar transition state which in turn accelerates the SN1 reaction.

If the initial compound is chiral then SN1 reaction ends up with racemization of the product.

Weaker bases being leaving group favor SN1 reaction.


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