Question

Question #572ed

Answer 1

What role does NaOH play in the synthesis of nerolin (β-methoxynaphthalene)?

The NaOH converts the β-naphthol into a much stronger nucleophile.

The synthesis of nerolin is an example of the Williamson ether synthesis, which is an `"S"_"N"2` displacement reaction.

Phenols are neutral molecules.

This makes them poor nucleophiles. They will not react with methyl iodide.

ArOH + CH₃-I `cancel(→)` ArO-CH₃ + HI

But phenols are also weak acids.

The strong base NaOH reacts with β-naphthol and converts it to the β-naphthoxide:

ArOH + OH⁻ → ArO⁻ + H₂O

Since the naphthoxide ion now has a negative charge, it is a much stronger nucleophile than the original naphthol.

It now reacts with the ethyl iodide in an `"S"_"N"2` reaction to form β-methoxynaphthalene.

ArO⁻ + CH₃-I → ArO-CH₃ + I⁻