The chiral chloride shown reacts with a good nucleophile by the S_N2 mechanism. From which direction does the nucleophile attack the stereogenic carbon?

From the side opposite the leaving group (backside, 180 degrees)

From the same side as the leaving group

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The chiral chloride shown reacts with a good nucleophile by the $S X_{N} 2$ mechanism. From which direction does the nucleophile attack the stereogenic carbon?

AFrom the side opposite the leaving group (backside, 180 degrees)
BFrom the same side as the leaving group
CPerpendicular to the C-Cl bond
DEqually from both faces

Answer: A

The compound is 2-chlorobutane's higher homologue, 2-chloropentane. In

S X_{N} 2

the nucleophile donates into the sigma* orbital of the C-Cl bond, which lies on the carbon side directly opposite chlorine. The nucleophile therefore enters at 180 degrees to the leaving group (backside attack), giving inversion.

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The chiral chloride shown reacts with a good nucleophile by the SXN​2 mechanism. From which direction does the nucleophile attack the stereogenic carbon?

Answer: A

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The chiral chloride shown reacts with a good nucleophile by the $S X_{N} 2$ mechanism. From which direction does the nucleophile attack the stereogenic carbon?