Preparation of 2-Methoxynaphthalene from 2-naphthol.
Principle: Phenols can be methylated to give methyl ethers. Methylation can be done either by using diazomethane or dimethyl sulphate in alkaline medium.
Reaction:
Procedure: Take 0.5 g 2-naphthol and 0.2 g NaOH in 5 ml distilled water in a beaker (25 ml). Heat on a wire gauze to obtain a clear solution. Cool the solution (10-15°C) and then add 0.35 ml dimethyl sulphate drop wise. After the addition is over, warm the mixture for one hour at 70-80°C and then cool. Filter the product and wash it with 10% sodium hydroxide solution and then with water. Dry the product, record the practical yield and re-crystallize it.
Re-crystallization: Dissolve the crude product in minimum amount of ethyl alcohol in a beaker by heating on a water bath. Filter the hot solution and cool the filtrate. Filter the white crystals of the product. Dry and record the melting point and TLC (using toluene as solvent).