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What is the procedure for synthesizing aspirin from salicylic acid and acetic anhydride, and what are the mechanisms involved in each step of the reaction?

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The synthesis of aspirin  acetylsalicylic acid  from salicylic acid and acetic anhydride is a common laboratory procedure and involves the following steps:1. Preparation of reagents and materials:- Salicylic acid- Acetic anhydride- Concentrated sulfuric acid  catalyst - Ice bath- Ethanol and distilled water  for recrystallization - Filter paper and funnel2. Procedure:a. In a dry Erlenmeyer flask, add a measured amount of salicylic acid.b. Add acetic anhydride to the flask, using a slight excess relative to the salicylic acid.c. Add a few drops of concentrated sulfuric acid as a catalyst to speed up the reaction.d. Gently heat the mixture on a hot plate or water bath for about 10-15 minutes, with occasional swirling to ensure proper mixing. The reaction should be kept below 100C to avoid side reactions.e. After the reaction time, cool the flask in an ice bath to promote the crystallization of aspirin.f. Add cold distilled water to the flask to decompose any remaining acetic anhydride and facilitate the precipitation of aspirin.g. Filter the mixture using filter paper and a funnel to collect the crude aspirin crystals.h. To purify the aspirin, dissolve the crude crystals in a minimal amount of warm ethanol and then add distilled water until the solution becomes cloudy. Cool the solution in an ice bath to recrystallize the purified aspirin.i. Filter the purified aspirin crystals, wash with cold distilled water, and let them dry.3. Reaction mechanism:The synthesis of aspirin is an example of esterification, where an acid  salicylic acid  reacts with an anhydride  acetic anhydride  to form an ester  acetylsalicylic acid  and a byproduct  acetic acid .a. The reaction begins with the protonation of the carbonyl oxygen of acetic anhydride by the sulfuric acid catalyst, making the carbonyl carbon more electrophilic.b. The nucleophilic oxygen atom of the hydroxyl group in salicylic acid attacks the electrophilic carbonyl carbon of the protonated acetic anhydride, forming a tetrahedral intermediate.c. The tetrahedral intermediate collapses, reforming the carbonyl group and releasing acetic acid as a byproduct.d. The final product, acetylsalicylic acid  aspirin , is formed.This procedure and the reaction mechanism are widely used in organic chemistry laboratories to teach esterification and the synthesis of pharmaceutical compounds.
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