Question

Pick out the facts regarding S_N2 reactions:

• A. It is a second order reaction
• B. It happens in two-steps
• C. It proceeds via the formation of a five-membered transition state
• D. Stereochemical inversion of configuration is possible

Answer 1

Answer: (A), (C), (D)

Stereochemical inversion of configuration is possible

S_N2 reactions are single-step reactions which follow second order kinetics. In these type of substitutions, the incoming nucleophile interacts with the alkyl halide causing the carbon-halide bond to break and a new bond is formed between the carbon and the attacking nucleophile. These two processes take place simultaneously in a single step and no intermediate is formed. The product formed will have an inverted configuration compared to the reactant.