Thin Layer Chromatography

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It was concluded that the product created was paracetamol when a thin layer chromatography test was performed and observed under ultraviolet light (which is discussed further down the page). An unknown substance was treated with acetic anhydrate and resulted with paracetamol. A compound that behaves in this matter is 4-aminophenol and is widespread in the industrial production of this drug. Upon these observations was the build up of “Chemical A” decided.  

When 4-aminophenol is t treated with acetic anhydrate it produces paracetamol. This procedure is the last stage of an industrial production of the drug called “Alvedon”.  Followed is a balanced equation of the reaction taken place. 

C6H7NO + C4H6O3 --> C8H9NO2 + C2H4O2 (acetic acid)
4-amin006F phenol + acetic anhydrate  paracetamol + acetic acid Mr 4-aminophenol - 109.13 g/mol
       acetic anhydrate - 102.09 g/mol
       paracetamol - 151.17 g/mol
       acetic acid - 60.05 g/mol       

As the experiment started, approximately 1.09 grams of 4-aminophenol was measured out to use in the experiment. This is (1.09/109.13) 9.99 x 10-3 moles of acetic anhydrate which should result in the same amount of moles of paracetamol, as these are created in a 1:1 ratio. The theoretical yield is (9.99 x 10-3 x 151.17) about 1.51g of paracetamol which is the amount that should be received. The actual yield at the end was 1.05g which is ≈ 70 % (69.54 %) (1.05/1.51 x 100) of the theoretical amount.

Recrystallization was performed to purify the compound received. The crystals of compound A were filtered out using filter paper. Doing a recrystalization purifies the substance but also decreases the yield as material is lost due to the finite solubility of paracetamol. This together with the product lost on the filter paper makes up for the primary loss of the substance, decreasing the yield.     

In practice it is impossible to receive the total theoretical yield (100%) as some molecules or atoms will be lost...
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