giving a suitable example justify the fact that sn2 reaction proceeds with inversion of configuration
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Answer:
Inversion of configuration usually happens when an organic compounds undergoes Nucelophilic substitution reaction by SN2 mechanism.
A Nucleophile (Electron rich species having affinity towards electron deficient centre) can attack the Stereocenter in two ways, like it can attack from frontside or from backside.
In frontside attack, the nucleophile attacks the stereocenter from the same side of the leaving group. This results in Retention Of Configuration. Retention of configuration means it is the preservation of integrity of the spatial arrangement of bonds to an asymmetric centre during a chemical reaction or transformation.
In the backside attack, the nucleophile attacks the stereocenter from the opposite side of the leaving group. This results in formation of the product having Inversion Of Configuration.
a) frontside resulting in product having Retention Of Configuration as seen in structure A &
b) on the other side ‘Y’ is attacking from the backside resulting in product having Inversion Of Configuration as seen in structure B.
Since Inversion Of Configuration occurs by SN2 reaction let us understand it in depth.
Nucleophilic Substitution-Bimolecular reaction mechanism (SN2)
This type of nucleophilic substitution reaction follows a second order kinetics, i.e., the rate depends upon the concentration of both the reactants-the nucleophile and the haloalkane
Rate = K [ R-X] [-OH]
Order = 1+1 = 2 (sum of power of concentration terms in rate law)
Some important features of SN2 mechanism
1.Reaction gets completed in a single step itself and that step itself will be the Rate Determining Step. Hence it belongs to 2nd order kinetics.
2.Inversion of configuration occurs.
3.Carbocation formation does not occur. But involves the transition state formation.
4.Primary alkyl group & non-polar solvent favours SN2 mechanism