The aim of this experiment is to purify a sample of impure acetanilide by process of recrystallisation. There is no chemical reaction involved in this experiment. The product obtained is a purified sample of the original starting material. Acetanilide is an amide of acetic acid, formed by actylation of the aromatic amine, aniline. In order to purify and analyse the sample of acetanilide, various experimental techniques such as recrystallisation, hot filtration, melting point determination and thin layer chromatography were used.
Recrystallisation is a technique used for the isolation and efficient purification of solid organic products and drugs. The impure sample of acetanilide was dissolved in a minimum amount of solvent at its boiling
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The crystals were then dried by placing them between two pieces of paper to remove excess water.
9. The sample was then weighed and the percentage yield calculated.
10. The crystals were viewed under a microscope to determine their shape.
11. Thin Layer Chromatography analysis of the sample was undertaken and the melting point of the sample was recorded.
Results and conclusions:
The results of this experiment is that I obtained a relatively low percentage yield of acetanilide crystals that were of a high purity.
My percentage yield was 20.8%, I have concluded that this low yield is due to the fact that I may have not rinsed the conical flask thoroughly enough when transferring the solution to the Buchner funnel for filtration therefore leaving some of the crystals behind.
I achieved an almost perfect melting point for my sample of acetanilide crystals of 114ºC. The melting point of pure acetanilide is 114.3ºC. I conclude that this is the result of a successful hot filtration where the insoluble impurities were removed and from having removed much of the excess water when drying the crystals.
(1a.) Acetanilide is one of a class of drugs with antipyretic and analgesic action.
(b)
(c) My crystals formed long, thin rectangular shaped