Question 12.6: Tell whether each of the following reactions is likely to be...
Tell whether each of the following reactions is likely to be S_{N}1, S_{N}2, E1, E1cB, or E2, and predict the product of each:
Strategy
Look carefully in each reaction at the substrate, leaving group, nucleophile, and solvent. Then decide from the preceding summary which kind of reaction is likely to be favored.
(a) A secondary, nonallylic substrate can undergo an S_{N}2 reaction with a good nucleophile in a polar aprotic solvent but will undergo an E2 reaction on treatment with a strong base in a protic solvent. In this case, E2 reaction is likely to predominate.
(b) A secondary benzylic substrate can undergo anS_{N}2 reaction on treatment with a nonbasic nucleophile in a polar aprotic solvent and will undergo an E2 reaction on treatment with a base. Under protic conditions, such as aqueous formic acid (HCO_{2}H), an S_{N}1 reaction is likely, along with some E1 reaction.
