In SN2, if the substrate is chiral, what is the typical stereochemical outcome?

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In SN2, if the substrate is chiral, what is the typical stereochemical outcome?

SN2 reactions occur in a single concerted step where the nucleophile attacks from the side opposite the leaving group. At a chiral carbon, this backside approach pushes the substituents around as the bond to the leaving group breaks and the bond to the nucleophile forms. The result is that the arrangement of groups around that carbon is reversed—its configuration is inverted. This is known as Walden inversion, so a chiral substrate gives a product with the opposite absolute configuration (relative to the original center). By contrast, reaching racemization would require a carbocation intermediate (SN1), and retention at a single stereocenter is not the typical outcome for SN2.

SN2 reactions occur in a single concerted step where the nucleophile attacks from the side opposite the leaving group. At a chiral carbon, this backside approach pushes the substituents around as the bond to the leaving group breaks and the bond to the nucleophile forms. The result is that the arrangement of groups around that carbon is reversed—its configuration is inverted. This is known as Walden inversion, so a chiral substrate gives a product with the opposite absolute configuration (relative to the original center). By contrast, reaching racemization would require a carbocation intermediate (SN1), and retention at a single stereocenter is not the typical outcome for SN2.

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