Final answer:
The SN1 reaction mechanism describes a unimolecular nucleophilic substitution where a carbocation intermediate is formed as the rate-determining step. Ethanol can act as both solvent and nucleophile, often leading to an ethoxy-substituted product. Tertiary alkyl halides favor the SN1 mechanism due to carbocation stability, while secondary and primary alkyl halides are less likely to follow this pathway.
Step-by-step explanation:
The SN1 reaction mechanism entails a nucleophilic substitution that is unimolecular, which refers to the reaction mechanism that proceeds in two distinct steps and the rate-determining step depends only on the concentration of the substrate. The first step involves the formation of a carbocation intermediate, which occurs when the leaving group (often a halogen) departs, forming a positively charged carbon atom. In the case of using AgNO₃ in ethanol, silver nitrate can help to precipitate the leaving group as a silver salt, such as silver chloride, therefore enhancing the formation of the carbocation.
Ethanol can act as both the solvent and the nucleophile in the reaction. Because the nucleophilic attack by ethanol on the carbocation is a fast, second step, ethanol usually competes with other nucleophiles present. However, given its high concentration as the solvent, ethanol is more likely to interact with the carbocation, leading to the formation of an ethoxy-substituted product.
Tertiary alkyl halides readily undergo SN1 reactions due to their ability to stabilize the carbocation intermediate, whereas primary alkyl halides are less likely to proceed via SN1 due to the instability of the resulting carbocation. Secondary alkyl halides exhibit mixed behavior; although they can form carbocations, they do not always proceed via an SN1 mechanism, depending on the specific conditions and the nature of the leaving group.