Predict the product of the following reactions. [Two of them are Williamson ether syntheses. Why isn't the other?].
(b)

Verified step by step guidance

1. Step 1: Identify the type of reaction. The first step involves the use of sodium hydride (NaH), which is a strong base. This will deprotonate the alcohol group, forming an alkoxide ion.
2. Step 2: Write the chemical equation for the deprotonation. The alcohol, tert-butanol, reacts with NaH to form the tert-butoxide ion and hydrogen gas. The reaction can be represented as: $R_{-}+{\mathrm{Na}}_{+}\to R_{-}{\mathrm{Na}}_{+}+H_2$
3. Step 3: Analyze the second step of the reaction. The alkoxide ion formed in the first step will act as a nucleophile and attack the electrophilic carbon in the alkyl iodide, leading to the formation of an ether. This is a typical Williamson ether synthesis.
4. Step 4: Consider the structure of the alkyl iodide. The alkyl iodide is connected to a silicon group, which is not typically involved in Williamson ether synthesis. This suggests that the reaction may not proceed as a typical Williamson ether synthesis.
5. Step 5: Predict the product. The tert-butoxide ion will likely attack the carbon adjacent to the iodine, displacing the iodide ion and forming an ether linkage. However, the presence of the silicon group may influence the reaction pathway or product stability.

Key Concepts

Williamson Ether Synthesis

Williamson ether synthesis is a method for creating ethers through the reaction of an alkoxide ion with a primary alkyl halide. This reaction typically involves an SN2 mechanism, where the nucleophile (alkoxide) attacks the electrophilic carbon of the alkyl halide, resulting in the formation of an ether. The choice of reactants is crucial, as steric hindrance can prevent successful ether formation.

SN2 Mechanism

The SN2 mechanism is a type of nucleophilic substitution reaction characterized by a single concerted step where the nucleophile attacks the electrophile while the leaving group departs. This bimolecular process results in the inversion of configuration at the carbon center. It is favored by primary substrates due to less steric hindrance, making it essential for understanding the conditions under which Williamson ether synthesis occurs.

Reactivity of Alkyl Halides

The reactivity of alkyl halides in nucleophilic substitution reactions depends on their structure and the nature of the leaving group. Primary alkyl halides are more reactive in SN2 reactions due to less steric hindrance, while tertiary halides favor SN1 mechanisms due to carbocation stability. Understanding this reactivity is key to predicting the outcomes of reactions, including why some reactions may not follow the Williamson ether synthesis pathway.