Question

Place 3.0 g of salicylic acid in a 125-ml Erlenmeyer flask. Carefully add, stirring constantly, 6 mL of acetic anhydride, followed by 10 drops of concentrated sulfuric acid. Swirl the contents of the flask so that the reactants are thoroughly mixed. Stopper the flask with a one- hole cork fitted with an inverted Pasteur pipet to prevent condensation of water in the reaction flask during heating on the steam bath. Heat the flask in a boiling-water or steam bath for 15 min. Remove the flask from the bath. While the contents are still hot, cautiously add 5 mL of ice water all at once. After the reaction subsides, add 35 mL of water and chill the contents of the flask in an ice bath. Use a stirring rod to break up any lumps that may Collect the product by vacuum filtration, using a Hirsch funnel or a small Büchner funnel. In the funnel, rinse the product with 15 mL of ice water, then draw air through the product for several minutes. Transfer the solid to a sheet of dry filter paper, and allow it to dry thoroughly. Weigh the dry solid to determine the yield, and determine its melting point. form. Dispose of the aqueous filtrate in the container designated for aqueous waste. Discard the recrystallization filtrate in a waste bottle for nonhalogenated organic solvents. Le Prepare a hot-water bath using a 250-ml beaker and a hotplate. Adjust the water temperature to just under the boiling point (about 90°C). Place 0.105 g of salicylic acid in a 5-mL conical vial*** Using an autopipet, add 0.240 mL of acetic anhydride and I drop of concentrated phosphoric acid. Add a small boiling stone and attach an air condenser. Clamp this assembly in such a way that the reaction vial is partially submerged in the water bath (Figure 21.1). Heat the mixture until the solid dissolves completely, and continue to heat it for 3-4 min. Remove the apparatus from the water bath. While the contents of the vial are still hot, cautiously add 0.5 mL of cold water all at once through the air condenser (to hydrolyze excess acetic anhydride). After the reaction subsides, remove the air condenser, remove the boiling stone with forceps, and rinse it with 1 mL of water, allowing the water to drop into the vial. Add 2 mL of water to the vial and chill it in an ice bath. Use a microspatula to stir the mixture and break up any lumps that may form. Collect the product by vacuum filtration, using a Hirsch funnel or a small Büchner funnel. In the funnel, rinse the product with several 0.5-ml portions of ice water. Then air- dry the product on the funnel (vacuum on) for 5 min. Transfer the product to a vessel of known weight and complete the drying process. Weigh the dry solid to determine the yield, and determine its melting point. Dispose of the aqueous filtrate in the container designated for aqueous waste.