Falak MdahiChem 203.2The synthesis of acetanilide from acetic anhydride and anilineIntroductionRecrystallization is a technique used to purify solids that contain small amounts impurities. It is used to isolate pure solids from a supersaturated solution leaving the impurities in the solvent (1). The solid containing the impurities is placed in a hot solvent and upon cooling, the compound precipitates in its purified form while the impurities remain in the solvent (1). There are six steps to undergo recrystallization of a solid. The first step is to choose a suitable recrystallization solvent. This step is crucial for a successful recrystallization experiment. Solubility comes into playA mixture of 2 ml aniline, 15 ml deionized water and 3 ml acetic anhydride was stirred. After thirty minutes, the reaction was complete and the product was completely precipitated out of solution. Vacuum filtration was used to isolate crude acetanilide using a 125 mL filter flask and a porcelain Büchner funnel. The product was then washed with 2 mL of ice water and left to dry for around twenty minutes. The observed melting point for crude acetanilide was 114.3°C to 115.7°C. The second procedure was to find a suitable solvent to recrystallize the crude acetanilide. A sand bath was set up and 0.5 ml of each solvent was added to 50 mg of acetanilide in four different test tubes. The four solvents used to test the solubility of acetanilide were water, ethanol, dichloromethane, and hexanes. If the solid dissolved in the solvent at room temperature, then it was too soluble and this solvent could be removed. Acetanilide completely dissolved in ethanol and dichloromethane, eliminating them as a suitable solvent. If the solid did not dissolve at room temperature, it was then placed in the sand bath and allowed to boil. If the solid dissolved it was placed in the ice bath and if crystals came out of solution the appropriate solvent was found. The appropriate solvent was water because the crystals came out when placed in the ice bath. The obtained NMR spectra were very similar to those of the predicted results. The methylhydrogen group showed a single peak at 2.153 ppm. The results were a little off the expected change of 2.2 to 2.9 ppm, but not by much. Next are the aromatic ring hydrogens with a range of 7.065 to 7.436 ppm consisting of several peaks, these also correspond to the expected shift of 6.5 to 8.0 ppm. The last signal belonged to that of hydrogen in the amide which had a peak at 7.571 ppm, which is well within the range of the expected shift between 5.0 and 9.0 ppm. Overall, NMR proved that the purified acetanilide contained very few impurities present in the