Freidal Crafts Alkylation Reaction

Friedel Crafts Alkylation Reaction

Introduction: In the experiment we will create 1,4-Di-t-Butyl-2,5-Dimethoxybenzene by performing a Friedel-Crafts reaction on 1,4-Dimethoxybenzene. In the reaction a t-butyl carbocation will be added on to the 1,4-Dimethoxybenzene. The t-butyl carbocation will be formed by a reaction of t-butyl alcohol with sulfuric acid. To perform the reaction we will create a mixture of the 1,4-Dimethoxybenzene, t-butyl alcohol with acetic acid. To this mixture we will add sulfuric acid dropwise through a separation funnel. We will then add this mixture to some crushed ice and water to precipitate the product. We will then filter the product, recrystallize the product, and then filter it again. After we have a product, we will record the weight and the melting point.

Table of Reagents: Mol. Wt. Mp. density

1,4-Dimethoxybenzene 138.17 g 57 oC

t-Butyl alcohol 74.12 g .79 g/ml

Sulfuric Acid 98.08 g 1.84 g/ml

Methanol 32.05 g

Ethanol 46.08 g

1,4-Di-t-butyl-2,5-dimethyloxybenzene 250.37 g 104-105 oC

Safety Information:

Use caution with the sulfuric acid as it is corrosive and can cause severe burns. Keep heat and flames away from the methanol and ethanol, as both are flammable. Dispose of all wastes in the proper containers. Dispose of all broken glass in the broken glass container. Wear gloves and goggles the entire time in the lab for safety.

Procedure:

1. Obtain 3 g of 1,4-dimethoxybenzene, 5 mL of t-butyl alcohol, and 10 ml of acetic acid and place all in a 125 ml flask, and cool the flask in ice water.

2. Place 10 ml of sulfuric acid in a 50 mL flask and cool it in ice water

3. Set up the seperatory funnel above the larger flask and clamp it to a ring stand.

4. Add the sulfuric acid to the funnel, and add it to the larger flask over a time period of 5 minutes, making sure to continuously stir the larger flask.

5. After the sulfuric acid is added, swirl the flask at room temperature for 5-10 minutes.

6. Add 15g of cracked ice to the flask with the reagents and add enough water to fill the flask Ñ* of the way full.

7. Filter the solution by gentle vacuum filtration.

8. Wash the product with three 15 mL portions of cold distilled water.

9. Turn the water on full force and wash the product with three 10 mL portions of ice cold methanol.

10. Recrystallize the product with 10-15 mL of ethanol.

11. Record the mass of the Product and the melting points.

Data:

1,4-Dimethoxybenzene - 3.017g

Final crystal weight- 4.328 g