Give three methods of preparation of anisole.

Anisole, also known as methoxybenzene, is an aromatic compound that can be prepared through various methods. Here are three common methods for its preparation:

Williamson Ether Synthesis:
The Williamson ether synthesis is a classic method for the preparation of ethers, including anisole. In this method, an alkoxide ion is used to react with an alkyl halide. Here's the step-by-step procedure:

i. Prepare sodium or potassium alkoxide by reacting sodium or potassium metal with an alcohol (e.g., sodium ethoxide for anisole).
ii. React the alkoxide with a halobenzene (e.g., bromobenzene) in an anhydrous solvent, such as dry ether or tetrahydrofuran (THF).
iii. The reaction will result in the formation of anisole and a sodium or potassium halide salt. The product can be separated and purified through distillation or other appropriate methods.

The general reaction for this method is:
Ar-X + R-O-Na/K → Ar-OR' + Na/K-X
where Ar represents the aromatic ring, X is the halogen, R is the alkyl group, and R' is the methoxy group.

Methylation of Phenol:
Another method to prepare anisole involves the methylation of phenol using a methylating agent like dimethyl sulfate or methyl iodide. Here's how it's done:

i. Dissolve phenol in a suitable solvent (e.g., acetone or dimethyl sulfoxide).
ii. Add a strong base, such as sodium hydroxide (NaOH), to the solution to generate the phenoxide ion.
iii. React the phenoxide ion with a methylating agent (e.g., dimethyl sulfate) to introduce the methoxy group onto the phenol ring.
iv. The resulting product is anisole.

The general reaction for this method is:
C6H5OH + CH3-X → C6H5OCH3 + X-
where C6H5 represents the phenyl group, X is the leaving group (e.g., sulfate or iodide), and CH3 represents the methyl group.

Dow Process:
The Dow process is an industrial method for the production of anisole from phenol. It involves the reaction of phenol with methanol in the presence of a solid acid catalyst, typically aluminum chloride (AlCl3) or aluminum oxide (Al2O3).

The reaction proceeds as follows:
C6H5OH + CH3OH → C6H5OCH3 + H2O

The use of a solid acid catalyst facilitates the reaction and allows for the selective formation of anisole. After the reaction, anisole can be separated and purified by distillation.

These methods provide different approaches to synthesize anisole, depending on the specific requirements and conditions of the synthesis.