The most efficient method to prepare a high yield of acetylsalicylic acid aspirin from salicylic acid and acetic anhydride with minimal impurities involves the following steps:1. Stoichiometric calculation: Calculate the stoichiometric amounts of salicylic acid and acetic anhydride needed for the reaction. The balanced chemical equation for the synthesis of aspirin is: C7H6O3 salicylic acid + C4H6O3 acetic anhydride C9H8O4 acetylsalicylic acid + C2H4O2 acetic acid 2. Mixing reactants: Mix the calculated amounts of salicylic acid and acetic anhydride in a clean, dry round-bottom flask or an Erlenmeyer flask.3. Catalyst addition: Add a few drops of concentrated sulfuric acid H2SO4 or phosphoric acid H3PO4 as a catalyst to speed up the reaction.4. Heating: Heat the reaction mixture gently in a water bath or an oil bath at 80-90C for about 15-20 minutes with occasional stirring. This temperature range ensures that the reaction proceeds at a reasonable rate without causing excessive decomposition of the reactants or products.5. Cooling and precipitation: After the reaction is complete, cool the reaction mixture to room temperature. Then, add cold distilled water to the mixture to precipitate the acetylsalicylic acid.6. Filtration: Filter the precipitated acetylsalicylic acid using vacuum filtration or gravity filtration. Wash the solid product with cold distilled water to remove any remaining impurities.7. Recrystallization: To further purify the product, dissolve the crude acetylsalicylic acid in a minimal amount of hot ethanol or a mixture of ethanol and water. Then, add hot distilled water to the solution until it becomes cloudy. Allow the solution to cool slowly to room temperature, and then place it in an ice bath to promote crystal formation. Filter the crystals and wash them with cold distilled water.8. Drying: Dry the purified acetylsalicylic acid crystals in a desiccator or an oven at a low temperature 40-50C to remove any residual solvent.9. Yield determination: Weigh the purified acetylsalicylic acid and calculate the percentage yield based on the initial amounts of salicylic acid and acetic anhydride used.By following these steps, you can obtain a high yield of acetylsalicylic acid with minimal impurities.