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 is a bimolecular nucleophilic substitution, defined by:

• A one-step process where the nucleophile attacks the electrophilic carbon while the leaving group departs.
• Statement 1: True. The reaction rate is determined by the concentrations of both the nucleophile and the substrate, and thus rises with increased nucleophilicity.
• Statement 2: True. The "2" in S_N2 signifies a second-order reaction, relying on two reactants.
• Statement 3: True. Tertiary substrates are unsuited for the S_N2 mechanism because of steric hindrance.
• Statement 4: False. Optical rotation may change, but isn't guaranteed to shift from (+) to (-) or vice versa, as this depends on the specific nucleophile and substrate.