Question

The substrate is the same in parts a and b, however the mechanism that proceeds is different. Explain how the choice of solvent (acetone vs. methanol) influences the reaction mechanism between benzyl bromide and a nucleophile.

Answer 1

Answer:

See explanation

Explanation:

The reaction of a benzyl bromide with a nucleophile may proceed by SN1 or SN2 mechanism depending on the nature of the solvent used.

Since SN1 reaction involves the formation of a carbocation, it usually predominates in the presence of a poor nucleophiles and protic solvents. Hence when methanol is used as solvent and a poor nucleophile is used, SN1 mechanism predominates.

However, when acetone which is an aprotic solvent is used in the presence of a good nucleophile, SN2 reaction mechanism predominates.