Chapter 135 of 2363 min read
Nucleophilic substitution: SN1 and SN2
Why this is asked: SN2 is a single backside attack that gives complete inversion of configuration (Walden inversion) at the stereocentre; SN1 goes through a planar carbocation attacked from either face, giving near-racemisation instead — "inversion versus racemisation" is the fastest way to tell the two mechanisms apart in a question stem. SN1 favours 3° substrates and polar protic solvents that stabilise the carbocation; SN2 favours 1° substrates and is blocked by bulky groups at the reacting carbon.
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- •The major product of the reaction shown in the figure is:
- •Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The first compound shown undergoes the reaction faster than the second compound shown.
Reason (R): Iodine is a better leaving group because of its large size.
In the light of the above statements, choose the correct answer from the options given below:
- •The compound (from the four structures shown) that will undergo the reaction with the fastest rate is:
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