The preparation and TLC analysis of aspirin involves three main processes namely synthesis, purification, and the TLC analysis. The synthesis process involves a mixture of some of the elements that will be used in the TLC analysis while the purification process eliminating foreign elements from the components prepared in the synthesis process. Specifically, crude aspirin is crystallized in the purification process. Warm water is added to the crude aspirin in an Erlenmeyer flask then it is placed in an ice bath and left to crystallize for about 10 minutes. Afterward, 3ml of cold deionized water and about 2ml of cold ethanol are used to rinse the crystals.
To perform the TLC analysis, use a 400Ml beaker and a watch glass to create a chamber. Place 10ml of 9:1 mixture of ethyl acetate and methylene chloride in that order in the beaker making use of a 110mm filter paper. The filter paper is essential in saturating the chamber. Leave the solvent to rise to the top of the filter paper then place a silica gel coated TLC plate inside the beaker. Using 6 drops of the TLC solvent, dissolve 3mg each of the crude product, recrystallized product and salicylic in separate small beakers. Then use a different pipette to collect each of the three solutions and spot the TLC plate lightly. Leave the plate to develop until the solvent gets to about ½ inch from the top of the TLC plate. Remove the plate from the chamber and leave it to dry before examining it under the UV light.
Fig1.
Source: (Latech.edu, p1)
The figure above represents the structures of acetic anhydride, acetylsalicylic acid, and salicylic acid.
Works cited
Latech.edu, "Chemistry 104: Synthesis of Aspirin." Chem.latech.edu. N.p., 2017. Web. 5 Apr. 2018.
