anhydride, so be careful to avoid spattering. Then add 10 mL of water and cool the flask in an Ice bath. The product should soon begin to crystalize; If it does not, either scratch the inside d the flask with a glass rod to induce crystalization or add a tiny seed crystal d aspirin. When crystalization is complete, collect the solid by suction filtration and wash it with a few of cold water. Allow the product to air dry (until the next period, it necessary) and determine the weight and yield. Optional: If time permits, the crude product can be recrystailzed by dissolving it In the minimum amount of hot ethanol (about 3-4 ml), then adding 10 mL of water and heating almost to boiling. On cooling, the asprin crystallizes Pure acid is reported to molt at 135 degree C but the melting point is quite variable because of decomposition. Weigh about 0.10 g of add into a 3-ml conical vial. and add 0.24 mL of acetic anhydride and one drop of 85% phosphoric add. Add a small boiling chip, attach air condenser, and heat the flask in a water bath at about 90 degree C. After the salicylic acid has dissolved, continue heating for lour to live minutes, then remove the flask from the heating bath. While it is still hot, carefully add 0.5 mL of water through the condenser to hydrolyze the excess acetic anhydride. After the reaction subsides, add 2 mL of odd water and cod the flask in an ice bath. Collect the solid aspirin by suction filtration; rinse the product with several 0.5-mL portions of cold water. After allowing the aspirin to dry thoroughly, weigh it and calculate the percent yield. Aspirin is hydrolyzed in the human body by an enzyme known as an esterase. Write the overall equation for this hydrolysis reaction. The solubility of aspirin in water is 1 g per 300 mL at 25 degree C. Assuming that your crystallization and washing with water were done at this temperature, what weight of aspirin did you lose in the filtrate and washings? How much was your percent yield lowered by this loss? Oil of wintergreen, commonly used externally to relieve muscular and joint pain, is the methyl ester of salicylic add. Write an equation for its preparation from salicylic acid.
