www.sas.org/E-Bulletin/2002-02-01/chem/body.html
Attach a reflux condenser^ to the flask and heat to a boil with a Bunsen burner or hot plate while maintaining a flow of cold water through the jacket of the condenser (Figure 2). If left for several days the liquid may crystallize into a solid mass. Acetanilide is quite soluble in hot water, but only sparingly soluble (ca. Add about 100 mL of distilled or deionized water to the flask and heat until the crude acetanilide dissolves. Dark-colored droplets of immiscible liquid may be seen in the solution, apparently accounting for the color of the crude material. To improve the yield, dissolve any acetanilide remaining in the flask in hot water and again decant. Cool the combined solutions in an ice bath to precipitate the acetanilide as colorless leaflets. Filter off the crystals and allow them to air-dry in a shallow dish until any residual acetic acid has evaporated. The resulting product should be free of any odor of the acid. Nine grams or more of purified product should be recovered. As a test for acetanilide mix a small amount of acetanilide with an equal amount of sodium nitrite and sprinkle the mixture onto the surface of concentrated sulfuric acid.
OH) to produce a colored indicator which turns red in acid, blue-green in base. The phenyl group already present in acetanilide reacts similarly to phenol. To keep the flask from overturning, weight it down with a lead "doughnut". These are available from laboratory suppliers, bu t you can make your own by melting scrap lead and pouring into a suitable form. Another alternative is to buy a stick of bar solder and bend it into a circle. Next gradually add 7 grams of acetanilide while stirring with a thermometer until all, or nearly all, has dissolved. At the outset much heat is evolved and care must be taken to keep the temperature below 20 C by adding the acid slowly and keeping ice in the bath. Allow the flask to stand in ice water for about 15 minutes after addition of the acid. Then pour the contents of the flask, a slightly syrupy reddish liquid, into about 500 mL of ice water while stirring vigorously; Filter off the precipitate on a double layer of finely-woven cotton cloth in a large glass or plastic funnel, and wash on the filter with ice water. Take up the cloth and squeeze it gently to remove excess liquid. Take care not to lose yield by forcing the precipitate through the cloth. Finally, place the cloth with the precipitate in a shallow dish and allow to air dry for two or three weeks. When the product is sufficiently dry, break up the cake and pulverize. Bottle the p-nitroacetanilide without further purification. Paranitroacetanilide can be used to produce a "Pharaoh's Serpent" that far outstrips the tiny ones sold as fireworks; For a showy demonstration place a gram or two of p-nitroacetanilide in a small evaporating dish and add enough conc. Avoid too thin a mixture as this will simply fizzle instead of deflagrate. Place the dish on a gauze mat on a tripod and heat with a small Bunsen flame or alcohol lamp. Then, quite suddenly and without warning, it will deflagrate with a hissing sound and a large and dense cloud of white smoke. Only when the smoke starts to dissipate will the "serpent" come into view, a column of black ash the diameter of the dish and extending up two feet or more. It stays in place attached to the dish, but is so light than the dish doesn't overturn. Despite its light weight the ash is remarkably rugged and can be broken loose and handled gently without collapsing. This demonstration should only be done in a well-ventilated area, as the white fumes of sulfuric acid are extremely irritating. The answer is a phenomenon called resonance wherein the bonds between adjacent carbon atoms may be thought of as existing in a intermediate state between single and double. The Allihn condenser shown in Figure 2 is a pretty piece of glassware, but there's no specific requirement that one be used . An ordinary straight-tube (Liebig) condenser or any of the water-jacketed columns available at bargain prices from the SAS Store will do nicely. It is important to keep glacial acetic acid from contact with skin as it attacks the epidermis, loosening it to form extensive blisters. If contact does occur, immediately wash the affected area with soap and water.
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