Animated Solution for Chemistry - Organic Chemistry: The major product of the following reaction is

Imagine you are in a laboratory, and you are handed a flask containing m-cresol. Your task is to react it sequentially with aqueous sodium hydroxide ($\text{NaOH}$) and then methyl iodide (${\text{CH}}_3\text{I}$).

This might seem like a simple two-step process, but it is actually one of the most elegant and fundamental reactions in organic chemistry. Let's break down exactly what happens at the molecular level.

In the first step, we introduce aqueous $\text{NaOH}$ to our m-cresol. Now, we know that $\text{NaOH}$ is a strong base. But what about m-cresol?

Because of the benzene ring, the hydroxyl ($-\text{OH}$) group in phenols is significantly more acidic than in regular aliphatic alcohols. The benzene ring stabilizes the resulting negative charge through resonance.

Therefore, a classic acid-base reaction occurs. The strong base easily abstracts the acidic proton from the phenol, generating a sodium phenoxide ion. This step is crucial because it transforms our relatively weak nucleophile (phenol) into a powerhouse nucleophile (phenoxide).

Now that we have our highly reactive phenoxide ion, we introduce the second reagent: methyl iodide (${\text{CH}}_3\text{I}$).

Methyl iodide is a primary alkyl halide. It has a highly electrophilic carbon atom attached to a good leaving group (iodide), and it has virtually no steric hindrance. This is the perfect setup for an ${\text{S}}_{N}2$ reaction.

The negatively charged oxygen of the phenoxide ion swoops in and attacks the electrophilic carbon of the methyl group from the backside. Simultaneously, the carbon-iodine bond breaks, and the iodide ion leaves.

As the dust settles from the ${\text{S}}_{N}2$ attack, a new carbon-oxygen bond is formed. We have successfully created an ether linkage!

The final product is 3-methoxytoluene, also known as m-methylanisole.

This entire sequence—deprotonating an alcohol or phenol to form an alkoxide/phenoxide, and then reacting it with a primary alkyl halide—is famously known as the Williamson Ether Synthesis. It is a reliable and high-yielding method for synthesizing asymmetric ethers.