Make Formic Acid

Summary

In this video, the process of synthesizing formic acid from glycerol and oxalic acid is explained step by step. The video demonstrates how to esterify oxalic acid with glycerol, heat the mixture to release carbon dioxide, and hydrolyze it to separate the formic acid. The process includes multiple distillation cycles to purify the formic acid, while emphasizing safety precautions due to potential toxic by-products like acrolein. The video concludes with a recommendation to store the azeotropic mixture of formic acid and water for most amateur uses, along with a brief mention of its application in making silver conductive ink.

Takeaways

• 😀 Safety first: Always work outside or in a fume hood to avoid exposure to toxic substances like acrolein.
• 😀 Glycerol and oxalic acid are the key ingredients for making formic acid in this experiment.
• 😀 Oxalic acid is essentially formic acid with carbon dioxide, and the goal is to break off the carbon dioxide through heating.
• 😀 Glycerol is esterified with oxalic acid to prevent unwanted reactions, and this reaction is stabilized during the process.
• 😀 The reaction starts with distilling off excess water, followed by the formation of glyceryl oxalate ester.
• 😀 The heating process leads to the formation of glyceryl monoformate, which then decomposes to release formic acid.
• 😀 To ensure the reaction completes properly, water is added back to hydrolyze the glyceryl monoformate and release formic acid.
• 😀 The process involves multiple cycles of adding oxalic acid, heating, and distilling to produce formic acid.
• 😀 If glycerol decomposes or the mixture turns black, it means the process has gone too far, and a new cycle should start.
• 😀 The final product is a crude formic acid mixture, which can be purified through fractional distillation, with careful temperature management to avoid impurities like acrolein.
• 😀 For most uses, the azeotropic formic acid mixture (77.5% formic acid) is sufficient and should be stored rather than further dehydrated to avoid producing carbon monoxide.

Q & A

What is the purpose of the experiment described in the video?

The purpose of the experiment is to make formic acid from glycerol and oxalic acid, which involves esterification, heating, and distillation processes.

Why is it necessary to esterify oxalic acid with glycerol before heating?

Esterifying oxalic acid with glycerol stabilizes the reaction and prevents unwanted decomposition that could occur if pure oxalic acid were used.

What temperature range should be maintained during the heating process?

The temperature should be kept between 105 and 120 degrees Celsius to avoid decomposition of the reactants.

What chemical reaction occurs when oxalic acid reacts with glycerol?

The oxalic acid reacts with glycerol to form glyceryl oxalate ester, which then decomposes to produce glyceryl monoformate and carbon dioxide.

What is the role of carbon dioxide in the reaction?

Carbon dioxide is released during the decomposition of glyceryl oxalate ester and plays a key role in converting the oxalic acid into formic acid.

Why is it important to maintain the proper water content during the reaction?

Maintaining the proper water content ensures that the glyceryl monoformate can hydrolyze into formic acid, which is necessary for the formation of pure formic acid.

How is formic acid separated from glycerol during the reaction?

Formic acid is separated from glycerol by heating and distillation, with the formic acid being released and collected as the reaction progresses.

What impurities can form during the decomposition of glycerol esters, and how are they handled?

The impurities include acrolein and allyl alcohol, which are volatile and toxic. They are separated by fractional distillation to ensure the purity of formic acid.

What is the final product of the distillation process?

The final product of the distillation process is an azeotropic mixture of 77.5% formic acid and water.

Why is it recommended to store formic acid as an azeotrope instead of dehydrating it further?

It is recommended to store formic acid as an azeotrope because further dehydration could generate small amounts of carbon monoxide, which is hazardous.