Aspirin synthesis from salicylic acid.
Introduction
The Introduction is written in Present Tense. Brief history and technique overview.
Acetylsalicylic acid (ASA), which is being sold under the trade name "aspirin" by the Bayer
Company is synthesized by the conversion of Salicylic acid (SA) to Acetylsalicylic acid (ASA)
using acetic anhydride in the presence of phosphoric acid acting as a catalyst.
The reaction involves the conversion of a phenol to an ester. This reaction is reversible, which is
why aspirin commonly smells of vinegar, as the ASA hydrolyzes in air back to SA and acetic
acid.
Reaction :
Iron (III) chloride (FeCl3) reacts with phenols to form brightly colored complexes, thus providing
an excellent means for testing the effectiveness of the ASA to SA conversion. (ASA does not
react because the phenol group is acetylated.
Experimental Procedure:
Past Tense. What did you do exactly? Someone of similar training should be able to repeat the
experiment using these instructions and obtain your results.
2.0 grams of salicylic acid, 5.0 mL of acetic anhydride and 5 drops of 85% phosphoric acid
solution were placed into a 50 mL Erlenmeyer flask. A 70-80 °C hot water bath was prepared by
placing a 250 mL beaker on a hot plate with a thermometer to monitor temperature.
The 50 mL Erlenmeyer flask with the mixture of salicylic acid, acetic anhydride, and phosphoric
acid was partially submerged in the water bath and heated for 15 minutes until vapors ceased to
be released. After 10 minutes of heating the submerged flask passed, 2 mL of distilled water was
added to the flask. Then, once the reaction reached completion the flask was removed and 20 mL
of distilled water was added. The flask was left to cool to room temperature before being placed
in an ice bath for 5 minutes to allow crystallization to occur. A vacuum filtration was set up and
the mixture was filtered via vacuum filtration. Once the liquid had been drawn out of the
mixture, the crystals were washed with 5 mL of cold, distilled water. This was repeated once
more. The vacuum filtration apparatus was left on for several minutes to aid in the drying of the
solid product before it was weighed and recorded.
synthesis of aspirin lab report
