How to make formic acid (from oxalic acid)

Summary

In this video, the creator demonstrates how to synthesize formic acid from oxalic acid, explaining the process and reaction in detail. Starting with 100g of oxalic acid dihydrate and recycled glycerin as a catalyst, they perform a simple distillation to extract the formic acid. The reaction produces CO2 gas, and the formic acid is purified through distillation. The creator shares insights into the chemical mechanisms, potential side products, and highlights the yield of 57%. Although the process is not optimal due to CO2 loss, they plan to purify the acid further in a future video.

Takeaways

• 😀 The process begins by synthesizing formic acid from oxalic acid using glycerin as a catalyst.
• 😀 100g of oxalic acid dihydrate is used, as water is necessary for the reaction.
• 😀 Glycerin (50g) is added to the mixture as a catalyst, which helps form an ester with oxalic acid.
• 😀 Sand is included in the reaction mixture to ensure even boiling and facilitate the reaction.
• 😀 The reaction takes place under simple distillation conditions, where the formic acid is distilled off.
• 😀 CO2 gas is released during the reaction, signaling that the reaction is progressing.
• 😀 The reaction temperature rises to around 110°C, indicating the start of the process and CO2 release.
• 😀 After some time, formic acid begins to distill, showing that the reaction is successful.
• 😀 The crude formic acid collected represents a 57% yield in relation to the oxalic acid used.
• 😀 After the distillation, impurities like aldehyde alcohol may remain in the crude formic acid, requiring further purification.
• 😀 The process involves a decomposition of oxalic acid into formic acid and CO2 gas, and the reaction is stopped once CO2 production slows down.

Q & A

Why is oxalic acid dihydrate used instead of anhydrous oxalic acid in this reaction?

Oxalic acid dihydrate is used because water is needed for the reaction. Anhydrous oxalic acid lacks this water, which would prevent the necessary esterification and decomposition steps from occurring.

What role does glycerin play in the production of formic acid?

Glycerin acts as a catalyst in the reaction. It first forms an ester with oxalic acid, which then decomposes back into glycerin and formic acid when water is present.

Why is sand added to the reaction mixture?

Sand is added to promote even boiling and help with the uniform distribution of heat, ensuring the reaction proceeds smoothly and safely.

What is the significance of the Liebig condenser in the setup?

The Liebig condenser is used to cool the vapors produced during distillation. It condenses the vapor back into liquid form, allowing for the collection of the formic acid distillate.

What is the purpose of adding sodium hydroxide solution during the reaction?

Sodium hydroxide solution reacts with the CO2 gas produced during the reaction. It also helps indicate when the reaction is complete, as CO2 production stops once the reaction is finished.

How is the end of the reaction determined?

The end of the reaction is indicated by a decrease in CO2 production, a slowdown in boiling, and a rise in temperature. These signals suggest that the reaction has reached completion.

What safety considerations should be taken into account during this reaction?

It is important to monitor the temperature and pressure carefully to prevent the formation of dangerous side products. Additionally, disconnecting the vacuum adapter during cooling is crucial to avoid accidental backflow of the sodium hydroxide solution.

Why is the crude formic acid yield only 52%?

The yield is relatively low because a significant amount of oxalic acid is converted into CO2 gas during the reaction, which reduces the amount of formic acid produced.

What could be done to improve the yield of formic acid in this reaction?

To improve the yield, the reaction could be optimized by reducing the amount of CO2 gas produced, perhaps by using a more controlled reaction setup or using a different method of decomposition.

How can the formic acid be purified after distillation?

The formic acid can be purified by using lead nitrate to remove impurities, specifically the presence of any remaining alcohols or other byproducts from the esterification process.