Acetylsalicylic Acid [50-78-2-A] C9H8O4
About the reaction: Salicylic acid is O-acetylated by reaction with acetic anhydride.
Procedure: In a 100-ml round-bottom flask, 13.8 g (0.10 mol) of salicylic acid and 11.4 ml (0.12 mol) of freshly distilled acetic anhydride are combined. After adding 1-2 drops of concentrated sulfuric acid, quickly attach a reflux condenser (with a drying tube) to the flask and wait for the exothermic reaction to subside. Then, heat and stir for two hours at a bath temperature of 95-100 °C to complete the reaction. Once the reaction mixture has cooled, pour it into 30 ml of ice water, causing the product to precipitate. Filter off the product and purify by recrystallization from water/dioxane (1:1). In this way, 14.0-14.9 g of acetylsalicylic acid is obtained in fine, colorless needles with a melting point of 137-138 °C. The yield corresponds to 78-83% of the theoretical yield.
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Note: The reaction progress can be monitored using thin-layer chromatography. SiO2-TLC plates and ethyl acetate as the solvent are used (Rf ≈ 60).
Source: Th. Eicher and H. J. Roth; Synthesis, Production and Characterization of Pharmaceuticals, Georg Thieme Verlag, Stuttgart 1986
Delivered by: Mephisto
Photo delivered by: Heuteufel
Created: 13/04/2006
Last updated: 31/12/2012
Other names: 2-Acetoxybenzoic acid; 2-Acetyloxybenzoic acid; Aspirin; ASA; Acetylsalicylate