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.

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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.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.