Fridel Crafts Acylation

riedel- Crafts Acylation needs a stoichiometric amount of aluminum chloride rather than the catalytic amount required for alkylation. For the experiment the students ran a reflux of phthalic anhydride and m-xylene with aluminum chloride resulting in 2-(2',4' -Dimethylbenzoyl) benzoic acid. The students in this experiment resulted in a 25% recovery, which might be due to human error.

Intro(morgan):

Friedel-Crafts acylation, also known as an electrophilic aromatic substitution is a way to add different functional groups onto aromatic rings. This reaction has much significance as it the chemistry behind the production of gasoline, synthetic rubber, plastics and synthetic detergents. The students used m-xylene and phthalic anhydride in the presence of aluminum chloride to run this experiment to end up with 2-(2,4-Dimethylbenzoyl) benzoic acid as the end product. The aluminum chloride converts the anhydride into an electrophilic intermediate that has a carbocation which then reacts with the m-xylene.The final product is made by adding ice water and hydrochloric acid to the intermediate.

Procedure (Savannah):

First, 0.700g of anhydrous aluminum chloride was weighed or measured, quickly capped, and brought to the workstation. Next, 0.307g of phthalic anhydride and 1.80mL of m-xylene were added to the 5mL conical vial. A small magnetic stirrer was placed in the vial and then secured a cap to the top. The apparatus for the reflux was put together, attached to a ring stand, and placed under the turned-on fume hood. A gas trap was not used. The vial was then attached to the reflux condenser. The mixture was cooled to 0oC by using an ice bath (minimum 5oC; does not have to be exactly 0oC). The vial was taken off the condenser, the anhydrous aluminum chloride was added, and then the vial was quickly placed back on the condenser and stir for about two minutes. Once the two minutes had passed, the solution was heated on the hot plate to room temperature in order to start the reaction (26oC or when bubbles start to form). Once the solution reached room temperature (started to see bubbles), the solution was heated on reflux for twenty minutes. After the twenty minutes, the solution was cooled to 0oC while stirring. The vial was taken off the condenser and a stopper was put on the vial. While under the hood, the solution was poured into a vial that had 2mL of ice water and stirred well. While stirring, 0.5mL of concentrated hydrochloric acid was added, and then another 2mL of ice water was added to the vial. Once the solution was cooled to room temperature and 1mL of diethyl ether was poured in the vial. The tube was capped and shaken hard for a couple minutes, but was vented occasionally to relieve pressure. The organic phase was transferred to a 15mL test tube by using a Pasteur pipet. The aqueous layer was obtained with three portions of diethyl ether by combining the organic layers with the original ethyl extract. The ethereal solution (ether layer) was put in a small vial and concentrated to half its volume. The solution was cooled to below the boiling point and the rest of the diethereal extracts was added and was concentrated to half its volume. Rotary evaporation (the Rotovap) was used to concentrate the solution (if the Rotovap was full, the described distillation would have been used). After using the Rotovap, the vial was placed in an ice bath for a few minutes. After the solution had cooled, the solution was transferred and was run through a vacuum filtration to