An SN2 reaction is characterised by
Correct answer: C. a single step in which the nucleophile attacks as the leaving group departs, with second order kinetics
- A. a two step mechanism through a carbocation
- B. first order kinetics involving only the alkyl halide
- C. a single step in which the nucleophile attacks as the leaving group departs, with second order kinetics
- D. the formation of a free radical intermediate
Explanation
The nucleophile approaches from the side opposite the leaving group and bond forming and bond breaking occur together through a five coordinate transition state, so the rate depends on the concentrations of both the halide and the nucleophile. Because attack is from the back, the configuration at that carbon is inverted, an effect known as Walden inversion. Primary halides follow this route because they are least hindered.
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About Nucleophilic Substitution
Nucleophilic substitution replaces a leaving group in an alkyl halide when an electron-rich nucleophile attacks the carbon atom. The topic compares SN1 and SN2 mechanisms, including reaction conditions, substrate structure, solvent effects, nucleophile strength, carbocation formation and stereochemical changes, and distinguishes substitution from elimination.
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