Question

Which of the following statements about the S_N2 reaction mechanism is/are true?

• A. The rate of reaction increases with increasing nucleophilicity.
• B. The number 2 denotes a second-order reaction.
• C. Tertiary butyl substrates do not follow this mechanism.
• D. The optical rotation of substrates always changes from (+) to (-) or from (-) to (+) in the products.

Answer 1

The Correct Option is A, B, C

The S_N2 reaction mechanism is a bimolecular nucleophilic substitution reaction characterized by:

• A single step where the nucleophile attacks the electrophilic carbon and the leaving group departs simultaneously.
• Statement 1: True. The reaction rate depends on the concentration of both the nucleophile and the substrate, and hence increases with increasing nucleophilicity.
• Statement 2: True. The ”2” in S_N2 indicates that the reaction is second-order, dependent on two reactants.
• Statement 3: True. Tertiary substrates do not follow the S_N2 mechanism due to steric hindrance.
• Statement 4: False. Optical rotation may change, but it is not guaranteed to shift from (+) to (-) or vice versa, as this depends on the specific nucleophile and substrate.

Answer 2

Which of the following statements about the SN2 reaction mechanism is/are true?

• Option 1: The rate of reaction increases with increasing nucleophilicity.
• Option 2: The number 2 denotes a second-order reaction.
• Option 3: Tertiary butyl substrates do not follow this mechanism.
• Option 4: The optical rotation of substrates always changes from (+) to (-) or from (-) to (+) in the products.

All four statements are true.