Synthesis of Aspirin from Salicylic Acid & Acetic Anhydride

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In summary, the purpose of synthesizing aspirin from salicylic acid and acetic anhydride is to demonstrate the organic synthesis of a commonly used pain relief and anti-inflammatory medication. The reactants in this reaction are salicylic acid and acetic anhydride, while the products are aspirin and acetic acid. The mechanism of the synthesis is an esterification reaction, where the hydroxyl group of salicylic acid reacts with the carboxyl group of acetic anhydride to form an ester bond. The purity of the synthesized aspirin can be determined through a melting point test, with pure aspirin having a melting point of 135-136°C. Potential hazards of this experiment
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lha08
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Homework Statement


Write the complete mechanism for the acid-catalyzed formation of aspirin from salicylic acid and acetic anhydride


Homework Equations





The Attempt at a Solution


I basically know the reaction but I'm not sure how to start the mechanism...Like i know that it is a substitution reaction where the OH group and the CH3--C==O switch places but how does it start? Does the the H group from the OH group first leave, then the CH3--C==O group can attack the O?
 
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Its a bit like Fisher Esterification.
 
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Or is it the other way around where the CH3--C==O group leaves first and then the H from the OH group attacks the O?

it is important to understand the mechanism of a reaction in order to fully comprehend the process and its potential outcomes. The synthesis of aspirin from salicylic acid and acetic anhydride is a classic example of an acid-catalyzed esterification reaction. The mechanism begins with the acid-catalyzed protonation of the carbonyl oxygen in acetic anhydride, making it more electrophilic. This allows for the attack of the hydroxyl group on salicylic acid, resulting in the formation of an intermediate tetrahedral hemiacetal.

Next, the protonated hydroxyl group is eliminated, resulting in the formation of an acylium ion. This ion then undergoes a nucleophilic attack by the carboxylate anion of the salicylic acid, resulting in the formation of an ester and regenerating the acid catalyst. The final step involves the deprotonation of the newly formed ester, resulting in the formation of aspirin and acetic acid.

Overall, the mechanism for the acid-catalyzed formation of aspirin from salicylic acid and acetic anhydride involves multiple steps including protonation, elimination, nucleophilic attack, and deprotonation. Understanding this mechanism is crucial for optimizing reaction conditions and ensuring the successful synthesis of aspirin.
 

1. What is the purpose of synthesizing aspirin from salicylic acid and acetic anhydride?

The purpose of this experiment is to demonstrate the organic synthesis of aspirin, a widely used medication for pain relief and inflammation. This process involves the reaction of salicylic acid and acetic anhydride to form aspirin and acetic acid.

2. What are the reactants and products in this synthesis reaction?

The reactants in this synthesis reaction are salicylic acid and acetic anhydride, while the products are aspirin and acetic acid.

3. What is the mechanism of the synthesis reaction?

The synthesis of aspirin from salicylic acid and acetic anhydride is an esterification reaction. This means that the hydroxyl group (-OH) of salicylic acid reacts with the carboxyl group (-COOH) of acetic anhydride, resulting in the formation of an ester bond and the production of aspirin and acetic acid.

4. How is the purity of the synthesized aspirin determined?

The purity of the synthesized aspirin can be determined through a melting point test. Pure aspirin has a melting point of 135-136°C, while impure aspirin will have a lower melting point due to the presence of impurities.

5. What are the potential hazards of this experiment?

The potential hazards of this experiment include exposure to corrosive substances such as acetic anhydride and acetic acid, as well as the risk of fire due to the flammability of these chemicals. Proper safety precautions, such as wearing protective gear and conducting the experiment in a well-ventilated area, should be taken to prevent any accidents.

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