Laboratory Synthesis of Aspirin

Summary

This video script details a laboratory demonstration of synthesizing aspirin from salicylic acid using acetic anhydride, catalyzed by sulfuric acid and heated to促成 reaction. The process includes crystallization for purification and a qualitative test with iron(III) chloride to confirm the absence of the phenol group in the final product, indicating successful synthesis and purification of aspirin.

Takeaways

• 🧪 The lab session focuses on an organic synthesis experiment to create aspirin.
• 💊 Aspirin, known as acetylsalicylic acid, is used for pain and inflammation relief.
• 🔬 Aspirin can be synthesized from salicylic acid and acetic anhydride in a single step.
• 🔍 The process involves using a strong acid as a catalyst and heating the reaction mixture.
• 🌡️ A hot water bath is used for even heating, reaching temperatures around 80-90°C.
• ⏱️ The reaction is left to proceed for about 10 minutes before cooling to room temperature.
• 💠 Crystallization is initiated by scratching the sides of the beaker or adding cold water.
• 🧊 An ice water bath is used to ensure complete crystal formation.
• 🕳️ Aspirin crystals are collected by vacuum filtration using a Büchner funnel.
• 🔄 Recrystallization is performed to purify the product, dissolving in ethanol and hot water.
• 🧪 A qualitative test using iron(III) chloride confirms the presence and purity of aspirin by color change.

Q & A

What is the main objective of the video?

The main objective of the video is to demonstrate an actual organic synthesis of aspirin, a drug used to reduce pain and inflammation.

What is the chemical name of aspirin?

The chemical name of aspirin is acetylsalicylic acid.

How is aspirin synthesized from salicylic acid?

Aspirin is synthesized from salicylic acid by reacting it with acetic anhydride to introduce the acetyl group.

What role does acetic anhydride play in the synthesis of aspirin?

Acetic anhydride is used to acetylate salicylic acid, thereby converting it to acetylsalicylic acid, which is aspirin.

What is the purpose of using a strong acid as a catalyst in the synthesis?

A strong acid, such as sulfuric acid, is used as a catalyst to speed up the reaction between salicylic acid and acetic anhydride.

Why is a hot water bath used instead of direct heating?

A hot water bath is used for even heating of the reaction mixture, preventing localized overheating that could occur with direct heating.

What is the significance of the crystallization step in the synthesis process?

The crystallization step is used to isolate and purify the synthesized aspirin from the reaction mixture.

How is the aspirin product collected after crystallization?

The aspirin product is collected by vacuum filtration after the crystallization step.

Why is recrystallization necessary in the purification process?

Recrystallization is necessary to further purify the aspirin product by removing any remaining impurities or starting materials.

What is the purpose of the qualitative test using iron(III) chloride at the end of the synthesis?

The qualitative test with iron(III) chloride is used to confirm the presence and purity of aspirin by checking for the absence of the phenol ring, which would indicate the presence of salicylic acid.

What is the final step to confirm the successful synthesis of aspirin?

The final step to confirm the successful synthesis of aspirin is to perform a qualitative test with iron(III) chloride, which should show no color change in the purified product, indicating the absence of salicylic acid.