Consider the following reaction. What product is formed from this reaction?
To answer this question, let’s take a look at the reactants. The cyclic structure has a hydroxy substituent. The hydroxy group is bonded to a carbon atom that has three alkyl substituents. So this molecule is a tertiary alcohol. The tertiary alcohol is reacted with hydrochloric acid in the presence of zinc chloride, a catalyst. All alcohols, whether primary, secondary, or tertiary, react with hydrohalic acids, like hydrochloric acid, via a substitution reaction.
A substitution reaction is a type of reaction where a part of a molecule is removed and replaced with something else. In the substitution reaction involving an alcohol and a hydrohalic acid, the part of the molecule that is removed is the hydroxy group. The hydroxy group is replaced by the halogen of the hydrohalic acid, in this case chlorine. The rest of the molecule, shown in blue, remains unaffected by this reaction. So the major product of this reaction will have the same general structure as the original molecule, except a chlorine atom will have replaced the hydroxy group. This reaction also produces a second product. The second product is formed when the hydroxy group is combined with the hydrogen of the hydrohalic acid to produce water.
The question wants to know what product is formed from this reaction. Since all of the answer choices contain cyclic structures, we need to determine which answer choice matches the cyclic structure that we drew. We can see that the answer choice which matches our structure is answer choice (C). Thus, the product formed from the reaction between the tertiary alcohol given in the question and hydrochloric acid is the structure shown in answer choice (C).