September 23, 2019, 06:05:30 AM
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Topic: Synthesis of methyl methanoate  (Read 334 times)

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Offline lukas.stib

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Synthesis of methyl methanoate
« on: September 08, 2019, 09:37:31 AM »
Hello chemists,

can you help me, what is the better synthesis for methyl methanoate? I was using a Soxhlet extractor with 3A molecular sieves, but there was a problem when the liquid overflowed from the extractor to the boiling flask, it boiled violently, and I lost a lot of ester. Was it a mistake that I was gradually adding power as the mixture diminished in the boiling flask? Now I do not know what is the better way or improvement of the synthesis.

Thank you very much.

Offline hollytara

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Re: Synthesis of methyl methanoate
« Reply #1 on: September 08, 2019, 10:28:38 PM »
You are using the Fischer esterification - methanol and methanoic acid?

Offline lukas.stib

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Re: Synthesis of methyl methanoate
« Reply #2 on: September 09, 2019, 01:22:31 AM »
Yes by stoichiometry.

Offline Babcock_Hall

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Re: Synthesis of methyl methanoate
« Reply #3 on: September 09, 2019, 12:00:31 PM »
Was it a mistake that I was gradually adding power as the mixture diminished in the boiling flask?
Can you explain why you added power?

Offline hollytara

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Re: Synthesis of methyl methanoate
« Reply #4 on: September 09, 2019, 12:43:22 PM »
Why are you using the soxhlet?  Methanol boils at 65 C, methanoic acid at 100 C, methyl methanoate at 32 C.

The classic Fischer would have you combine acid and alcohol with acid catalyst (usually H2SO4) and start to heat at a temperature that just barely boils the lower boiling component (methanol 65 C) in a distillation apparatus.  As the lower boiling ester forms, it will distill over at 32 C. 

32 C is pretty low - you may need to aggressively cool your distillation apparatus and collection flask to keep it from being lost to evaporation!

Offline lukas.stib

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Re: Synthesis of methyl methanoate
« Reply #5 on: September 09, 2019, 05:07:50 PM »
I will answer the above questions:

I was adding power because the mixture stopped boiling in the boiling flask, sometimes it did not boil, so I had to add power. But the problem is that as I increased the heating power to get the mixture to boil, so the ester poured from the soxhlet into the boiling flask, it boiled violently...
 

I use a molecular sieve 3A with soxhlet to drying ester because the ester is wet, and the balance is by drying shifted to the right side. I found this method on the Internet, said to be very good for high yield of ester.
I do not use sulfuric acid because it reacts with formic acid and it decomposes to carbon monoxide. Formic acid is strong, one of the strongest carboxylic acids, so it catalyzes itself.

What to try to pour formic acid with a little methanol into the boiling flask, heat it up and slowly add the drip of the methanol according to the rate of ester dropping?

Offline billnotgatez

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Re: Synthesis of methyl methanoate
« Reply #6 on: September 10, 2019, 02:06:02 PM »
When I first saw this post I wondered if the following is appropriate.
Boiling chip
https://en.wikipedia.org/wiki/Boiling_chip

Offline Babcock_Hall

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Re: Synthesis of methyl methanoate
« Reply #7 on: September 10, 2019, 02:48:40 PM »
Why try to make it when you can buy it?

Offline lukas.stib

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Re: Synthesis of methyl methanoate
« Reply #8 on: September 10, 2019, 04:23:50 PM »
I did not use cooking stones, but I used pieces of porcelain.

I like to synthesize substances for fun. When I buy substances, it's not a hobby.

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