Consider the following two substitution reactions: (I) (II) Which reaction proceeds at a faster rate, and what is the predominant mechanism for the formation of the given products?

Step-by-step solution

Both reactions involve a tertiary alkyl halide reacting with acetic acid, which is a weak nucleophile and a polar protic solvent. These conditions favor the S_N1 mechanism, where the rate-determining step is the cleavage of the carbon-halogen bond to form a carbocation. The rate of an S_N1 reaction depends on the leaving group ability. The bromide ion ( Br^- ) is a better leaving group than the chloride ion ( Cl^- ) because the C-Br bond is weaker and more easily broken than the C-Cl bond. Thus, tert-butyl bromide