Phenetole, also known as ethoxybenzene, is an aromatic ether commonly used as a solvent and as a precursor in organic synthesis. It can be prepared via Williamson ether synthesis, which involves the reaction of an alkoxide ion with a primary alkyl halide or sulfate ester. Here’s a simplified outline of the preparation of phenetole using this method:
Materials Needed:
- Sodium ethoxide (prepared from sodium metal and absolute ethanol)
- Bromobenzene (or another suitable aryl halide)
- Absolute ethanol (solvent)
Procedure:
- Preparation of Sodium Ethoxide: Sodium ethoxide is typically prepared by dissolving sodium metal in absolute ethanol. This reaction should be carried out under an inert atmosphere, such as nitrogen or argon, to prevent oxidation of the sodium metal. The reaction can be represented as follows: Na+C2H5OH→NaOC2H5+H2Na+C2H5OH→NaOC2H5+H2 The resulting solution contains sodium ethoxide (NaOC2H5NaOC2H5) in ethanol.
- Reaction with Bromobenzene: Once sodium ethoxide is prepared, it is added to a solution of bromobenzene in absolute ethanol. The reaction is carried out under reflux conditions (heating the mixture in a reflux condenser to maintain a constant temperature) to facilitate the reaction. The reaction between sodium ethoxide and bromobenzene proceeds via Williamson ether synthesis, resulting in the formation of phenetole. The reaction can be represented as follows: C6H5Br+NaOC2H5→C6H5OC2H5+NaBrC6H5Br+NaOC2H5→C6H5OC2H5+NaBr The product, phenetole (ethoxybenzene), is obtained as the organic layer in the reaction mixture.
- Isolation and Purification: After the reaction is complete, the mixture is allowed to cool, and the product is isolated by extraction with a suitable solvent (e.g., diethyl ether or dichloromethane). The organic layer containing phenetole is separated, and the solvent is removed under reduced pressure to obtain crude phenetole. Further purification may be achieved through techniques such as distillation or recrystallization.
Properties of Phenetole
| Property | Description |
|---|---|
| Chemical Formula | C8H10O |
| Molecular Weight | Approximately 122.19 g/mol |
| Physical State | Liquid at room temperature |
| Appearance | Colorless liquid |
| Odor | Sweet, aromatic odor |
| Melting Point | -33°C (-27°F) |
| Boiling Point | 169-172°C (336-342°F) |
| Density | ~0.945 g/cm at 20°C (68°F) 0r 967 kg/m³ |
| Solubility | Soluble in organic solvents such as ethanol, ether, and chloroform; slightly soluble in water. |
| Flash Point | 62°C (144°F) (closed cup) |
| Refractive Index | n<sub>D</sub> 1.514 (20°C) |
| Vapor Pressure | ~0.3 mmHg at 20°C (68°F) |
| Autoignition Temperature | ~270°C (518°F) |
| Hazards | May cause irritation to skin, eyes, and respiratory tract; flammable liquid; harmful if swallowed or inhaled. |