Preparation of Acetanilide

1398 WordsNov 28, 20126 Pages
Learning Activity 1 Preparation of Acetanilide Abstract Recrystallization is a common method of purifying organic substances through the difference in solubility at different temperature. In this experiment, acetanilide was produced by acetylation of aniline with acetic anhydride. The crude acetanilide was dissolved in a solvent in a heating water bath. The solution was cooled slowly in an ice bath as crystals form out. As the compound crystallizes from the solution, molecules of other compounds dissolved in solution are excluded from growing crystal lattice, yielding pure acetanilide. Acetanilide is slightly soluble in water, and stable under most conditions. Pure crystals are plate shaped and colorless to white. This experiment…show more content…
In the 19th century acetanilide was one of a large number of compounds used as experimental photographic developers. Acetanilide can be toxic by ingestion and has an LD50 (dose that kills half of test animals) for rats of 800 mg per kilogram of body weight. Ingestion of lesser quantities causes central nervous system depression. Skin exposure causes irritation, although chronic exposure can lead to dermatitis. It will also cause irritation to the lungs if inhaled. If it burns, it will produce some toxic byproducts such as nitrogen oxides and carbon monoxide. The observed methemoglobinemia after acetanilide administration was ascribed to the small proportion of acetanilide that is hydrolyzed to aniline in the body. Acetanilide is no longer used as a drug in its own right, although the success of its metabolite – paracetamol (acetaminophen) – is well known. V. Conclusion Recrystallizing solvent is a solvent that shows the desired solubility behavior for the substance to be crystallized. Identifying the ideal recrystallizing solvent of a compound is necessary to purify the organic compound.. In choosing the recrystallizing solvent, the compound should be insoluble at room temperature. While heating, the compound should be very soluble and upon cooling, it is insoluble. The unwanted impurities should be soluble at room temperature or insoluble during heating. The recovered crystals from the final procedure were only half of the

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