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
Phenols are neutral molecules.
This makes them poor nucleophiles. They will not react with methyl iodide.
ArOH + CH₃-I
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
ArO⁻ + CH₃-I → ArO-CH₃ + I⁻