Preparation of Cyclohexene from Cyclohexanol using Conc. H2SO4

Cyclohexene is an important organic compound that is widely used as a solvent and in the production of other chemicals. It can be prepared from cyclohexanol by using different methods, but one of the most commonly used methods is by using concentrated sulfuric acid. The steps involved in this method are as follows:

Materials Required:
- Cyclohexanol
- Concentrated sulfuric acid (H2SO4)
- Distilled water
- Separatory funnel
- Ice water bath
- Sodium carbonate (Na2CO3)
- Drying agent (such as anhydrous calcium chloride or magnesium sulfate)
- Round-bottom flask
- Reflux condenser
- Thermometer
- Heating mantle

Procedure:
1. In a round-bottom flask, add 20 mL of cyclohexanol.
2. Add 20 mL of concentrated sulfuric acid slowly and carefully with stirring.
3. Attach a reflux condenser to the flask and heat the mixture to 160-170°C using a heating mantle. Monitor the temperature using a thermometer.
4. Keep the mixture under reflux for 2-3 hours until the evolution of water ceases. The reaction mixture will start to turn yellow due to the formation of cyclohexene.
5. Cool the reaction mixture to room temperature and add 25 mL of distilled water with stirring. The water will dissolve the excess sulfuric acid and other impurities.
6. Transfer the mixture to a separatory funnel and add 10 mL of sodium carbonate solution to neutralize the remaining sulfuric acid. Shake the funnel gently and allow the layers to separate.
7. Collect the organic layer (the upper layer) in a clean, dry flask. Discard the aqueous layer (the lower layer).
8. Add a drying agent (such as anhydrous calcium chloride or magnesium sulfate) to the flask and shake it gently. The drying agent will absorb any remaining water.
9. Filter the solution using a filter paper to remove the drying agent.
10. Collect the product in a clean, dry flask and store it in a cool, dry place.

Advantages of using Conc. H2SO4:
- The reaction is fast and efficient.
- The yield of cyclohexene is high.
- The method is easy to perform and requires simple equipment.
- The byproducts formed are easily removed.

Disadvantages of using Conc. H2SO4:
- The method is not suitable for large-scale production due to the corrosive nature of the acid.
- The acid can cause severe burns and should be handled with care.
- The method produces a large amount of sulfur dioxide gas, which is a pollutant and harmful to the environment.
- The acid can react with other organic compounds, leading to side reactions and impurities in the product.

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