Friedel – Crafts Acylation: Synthesis of 4-Methoxyacetophenone
Introduction
Friedel-Crafts acylation of anisole with acetic anhydride was used in this experiement to synthesize 4-methoxyacetophenone with the use of a reflux apparatus. Friedel-Crafts reactions can be done by alkylation, which involves mixing an alkyl or acyl halide with a Lewis acid, or acylation, which is done with acid chlorides or anhydrides(Lefevre). Acylation was used because it does not have as many disadvantages aklyations reactions have such as polyalkylation, second electrophilic attacks, and the rearrangement of alkyl carbocation electrophile (McMurry). Acylation reactions require molar amounts of a Lewis catalyst, in our case Aluminum Chloride (AlCl 3) was used (Arata, Nakamura, & Shouji).
Materials and Methods
Reflux apparatus assembly
Using a condenser, Claisen adapter, and a 25 mL round-bottom flask, a reflux apparatus was assembled. The round-bottom flask, which had Anisole (.55g), a boiling chip and dichloromethane (5 mL) directly added to it, was attached to the Claisen adapter, which had a rubber septum in the opening directly over the flask. The condenser was attached to the other opening of the adapter. The top of the condenser was fitted with a rubber stopper equipped with a Y-tube. One of the arms of the Y-tube was connected to the water aspirator using rubber tubing with the other arm left open.
Conducting the Reaction
Aluminum chloride (AlCl3, 1.45 g) was quickly added to the round-bottom flask by removing the rubber septum, with caution as to minimize exposure of moisture from the air to the reaction mixture. The rubber septum was replaced and the reaction flask was cooled in an ice bath that was prepared in a 100-mL beaker. When AlCl3 was added to the mixture, the mixture began to bubble, changing the color from yellow to a dark purple. Using a plastic pipet, acetic anhydride (0.6 mL) was added to the mixture. The ice bath was removed and the water aspirator was turned on. A hot water bath was prepared by heating 300 mL of
Friedel-Crafts acylation of anisole with acetic anhydride was used in this experiement to synthesize 4-methoxyacetophenone with the use of a reflux apparatus. Friedel-Crafts reactions can be done by alkylation, which involves mixing an alkyl or acyl halide with a Lewis acid, or acylation, which is done with acid chlorides or anhydrides(Lefevre). Acylation was used because it does not have as many disadvantages aklyations reactions have such as polyalkylation, second electrophilic attacks, and the rearrangement of alkyl carbocation electrophile (McMurry). Acylation reactions require molar amounts of a Lewis catalyst, in our case Aluminum Chloride (AlCl 3) was used (Arata, Nakamura, & Shouji).
Materials and Methods
Reflux apparatus assembly
Using a condenser, Claisen adapter, and a 25 mL round-bottom flask, a reflux apparatus was assembled. The round-bottom flask, which had Anisole (.55g), a boiling chip and dichloromethane (5 mL) directly added to it, was attached to the Claisen adapter, which had a rubber septum in the opening directly over the flask. The condenser was attached to the other opening of the adapter. The top of the condenser was fitted with a rubber stopper equipped with a Y-tube. One of the arms of the Y-tube was connected to the water aspirator using rubber tubing with the other arm left open.
Conducting the Reaction
Aluminum chloride (AlCl3, 1.45 g) was quickly added to the round-bottom flask by removing the rubber septum, with caution as to minimize exposure of moisture from the air to the reaction mixture. The rubber septum was replaced and the reaction flask was cooled in an ice bath that was prepared in a 100-mL beaker. When AlCl3 was added to the mixture, the mixture began to bubble, changing the color from yellow to a dark purple. Using a plastic pipet, acetic anhydride (0.6 mL) was added to the mixture. The ice bath was removed and the water aspirator was turned on. A hot water bath was prepared by heating 300 mL of
Bibliography: Arata, K., Nakamura, H., & Shouji, M. (2000). Friedel–Crafts acylation of toluene catalyzed by solid superacids. Applied Catalysis A: Genera , 197 (2), 213-219. Lefevre. (1998). Organic Chemsitry II Laboraty Manual (1st Edition ed.). palmyra: H. A. Neidig . McMurry, J. Organic Chemistry (7th Edition ed.). Belmont : Brooks/Cole.