Diazoaminobenzene : Organic Synthesis

Summary

This video demonstrates the synthesis of diazoaminobenzene through a step-by-step process involving the reaction of aniline with sodium nitrite and hydrochloric acid. The procedure includes cooling the mixture, carefully controlling temperature, and adding sodium acetate to precipitate the product. After filtration and washing, the crude product is recrystallized using petroleum ether, followed by drying and weighing the final product. The video also covers the theoretical and practical yields, highlighting a 55% yield after purification. Along the way, viewers learn about the key steps in the reaction, along with tips for achieving a pure product.

Takeaways

• 😀 The experiment involves synthesizing diazoaminobenzene from aniline using diazotization.
• 😀 The reaction requires 7 grams of vanillin, 2.6 grams of sodium nitrite, 12 grams of concentrated hydrochloric acid, and 10.5 grams of sodium acetate.
• 😀 It is important to use freshly distilled aniline to avoid impurities that can cause the solution to turn dark.
• 😀 The reaction must be carefully controlled, keeping the temperature below 5°C during the addition of sodium nitrite to prevent unwanted side reactions.
• 😀 Sodium acetate is used to maintain the proper pH and help the formation of diazoaminobenzene.
• 😀 The temperature should not exceed 20°C during the reaction, and ice can be used to control the temperature if necessary.
• 😀 After the reaction, the crude product is filtered using a Buchner funnel and washed with cold water to remove water-soluble impurities.
• 😀 The crude product weighs around 11.2 grams before recrystallization.
• 😀 Recrystallization is done using petroleum ether, and activated charcoal is used to remove colored impurities.
• 😀 After recrystallization, the practical yield of the product is 4.1 grams, with a percentage yield of 55%.
• 😀 The video concludes with an acknowledgment of Patreon supporters, encouraging viewers to subscribe for future updates.

Q & A

What is the purpose of adding hydrochloric acid to the experiment?

Hydrochloric acid is used to dissolve aniline and form aniline hydrochloride, which is necessary for the diazotization reaction to proceed.

Why is it important to use freshly distilled aniline in the experiment?

Freshly distilled aniline is necessary to avoid impurities that could cause the solution to turn dark, which could interfere with the reaction and affect the yield.

What is the role of sodium nitrite in this reaction?

Sodium nitrite is used to generate the diazonium ion from aniline hydrochloride. The diazonium ion is essential for the formation of diazoaminobenzene.

Why must the temperature be maintained below 10°C during the addition of sodium nitrite?

Maintaining the temperature below 10°C prevents the formation of tarry, unwanted side products that can arise from elevated temperatures during the diazotization reaction.

What happens if the temperature rises above 20°C during the reaction?

If the temperature rises above 20°C, it could lead to the degradation of the diazonium salt and the formation of undesirable side products, compromising the reaction.

What is the purpose of adding sodium acetate to the reaction mixture?

Sodium acetate acts as a weak base, which helps in the precipitation of diazoaminobenzene. It also neutralizes excess acid and stabilizes the reaction mixture.

How does the addition of sodium acetate prevent unwanted reactions?

The addition of sodium acetate helps maintain the proper pH conditions for the stability of the diazonium salt, preventing premature reactions and ensuring the correct product formation.

What is the purpose of recrystallization in this experiment?

Recrystallization is used to purify the crude diazoaminobenzene by removing impurities and isolating the desired product in its purest form.

What solvent is used for recrystallization, and why is it chosen?

Petroleum ether is used as the solvent because it effectively dissolves the product during heating, while allowing the purified product to crystallize upon cooling.

What is the theoretical yield of the product, and how does it compare to the practical yield?

The theoretical yield of the diazoaminobenzene is 7.42 grams based on 7 grams of aniline, while the practical yield after recrystallization is 4.1 grams, resulting in a percentage yield of 55%.