Making Benzoic Acid (from sodium benzoate)

TL;DR

The video demonstrates the synthesis of benzoic acid through the reaction of sodium benzoate with hydrochloric acid, along with the process of recrystallization to obtain purer benzoic acid crystals.

Transcript

hey guys we're back today to make a little bit of benzoic acid I want to make it because it's a precursor to something called denatonium benzoate denatonium benzoate is often referred to as the most bitter compound known to man and to me this is interesting and I want to make it after I made the benzoic acid in this video I actually did proceed on ... Read More

Key Insights

• 💁 Benzoic acid can be synthesized by reacting sodium benzoate with hydrochloric acid, resulting in the formation of benzoic acid and sodium chloride.
• 👻 The low solubility of benzoic acid in water allows it to precipitate out as a white solid during the reaction.
• 😎 Recrystallization is an effective method to purify benzoic acid by dissolving it in a solvent, cooling the solution to allow crystals to form, and separating them from impurities.
• 😒 Benzoic acid has various applications in chemistry, including its use as a precursor for the synthesis of denatonium benzoate, benzoyl chloride, and benzoyl peroxide.
• 🎮 The synthesis of denatonium benzoate, benzoyl peroxide, and benzoyl chloride will be covered in future videos.
• 🎮 The crude benzoic acid obtained in the video was not highly pure, possibly due to the quality of sodium benzoate used.
• 🔮 Recrystallization improves the purity of benzoic acid, resulting in fluffy, odorless crystals.

Questions & Answers

Q: Why is benzoic acid used in the synthesis of denatonium benzoate?

Benzoic acid is used as a precursor in the synthesis of denatonium benzoate, a highly bitter compound. It serves as an important starting material for various chemical reactions.

Q: Can benzoic acid be used in acne creams and teeth whitening products?

Yes, benzoic acid can be used to produce benzoyl peroxide, which is a common ingredient in acne creams and teeth whitening products due to its antibacterial and oxidizing properties.

Q: What is the purpose of recrystallization in the synthesis of benzoic acid?

Recrystallization helps remove impurities from the crude benzoic acid, resulting in purer crystals. It involves dissolving the compound in a solvent, heating to dissolve all the solid, and then allowing it to slowly cool, allowing the pure crystals to form.

Q: What is the expected yield of benzoic acid in this synthesis?

The reaction between sodium benzoate and hydrochloric acid should have a near quantitative yield, meaning that almost 100% of sodium benzoate should be converted to benzoic acid. However, some benzoic acid may be lost during the recrystallization process, resulting in a yield of around 95%.

Summary & Key Takeaways

• The video shows the process of regenerating sodium benzoate to its acidic form, benzoic acid, using hydrochloric acid.

• A white precipitate of benzoic acid is formed when hydrochloric acid is added to sodium benzoate due to its low solubility in water.

• The crude benzoic acid is then subjected to recrystallization to obtain purer crystals.