Practice Problem 7.15 Acid-catalyzed dehydration of either 2-methyl-1-butanol or 3-methyl-1-butanol gives 2-methyl-2-butene as the major product. Write plausible mechanisms that explain these results. Practice Problem 7.16 When the compound called isoborneol is heated with $9\mathrm{M}$ sulfuric acid, the product of the reaction is the compound called camphene and not bornylene, as one might expect. Using models to assist you, write a step-by-step mechanism showing how camphene is formed. Isoborneol Camphene Bornylene 7.8B Rearrangement After Dehydration of a Primary Alcohol Rearrangements also accompany the dehydration of primary alcohols. Since a primary carbocation is unlikely to be formed during dehydration of a primary alcohol, the alkene that is produced initially from a primary alcohol arises by an E2 mechanism, as described in Section 7.7C. However, an alkene can accept a proton to generate a carbocation in a process that is essentially the reverse of the deprotonation step in the E1 mechanism for dehydration of an alcohol (Section 77A). When a terminal alkene does this by using its $\pi$ electrons to bond a proton at the terminal carbon, a car-