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Topic: Synthesis of propionic acid by salt+acid  (Read 1409 times)

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Offline lukas.stib

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Synthesis of propionic acid by salt+acid
« on: April 14, 2022, 01:54:49 PM »
Hello chemists,

please give me an advice. I want to make propionic acid by reacting sodium propionate with acid. I have 96% H2SO4, but I don't want to use it because I'm afraid it will destroy my propionate. It's already happened to me with sodium acetate, which turned black because H2SO4 dehydrated into elements. I don't know what acid would be effective. I have 85% phosphoric acid, can I use it? I want to get a lot of concentrated propionic acid, will the problem be 85% phosphoric acid?

Thank you. Lukáš S.

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Re: Synthesis of propionic acid by salt+acid
« Reply #1 on: April 14, 2022, 02:29:31 PM »
Use diluted sulfuric acid 10 to 20 %.

Offline lukas.stib

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Re: Synthesis of propionic acid by salt+acid
« Reply #2 on: April 14, 2022, 02:51:17 PM »
But it will be too much water ...

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Re: Synthesis of propionic acid by salt+acid
« Reply #3 on: April 14, 2022, 02:52:15 PM »
Of course you have to do Destillation.

Offline lukas.stib

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Re: Synthesis of propionic acid by salt+acid
« Reply #4 on: April 15, 2022, 01:38:38 AM »
And 85% phosphoric acid? I think this is better. Much less water and phosphoric acid also certainly reacts and has no destructive effects like H2SO4. Or 35% HCl is too good I think...
« Last Edit: April 15, 2022, 01:53:35 AM by lukas.stib »

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Re: Synthesis of propionic acid by salt+acid
« Reply #5 on: April 15, 2022, 04:23:17 AM »
You can do.

Offline Aldebaran

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Re: Synthesis of propionic acid by salt+acid
« Reply #6 on: April 15, 2022, 11:30:45 AM »
Bear in mind propanoic acid forms a constant boiling point mixture with water. I note you want to make a lot of the concentrated acid so unless you particularly want to experiment with methods of further concentrating the azeotropic mixture it might be easier to just buy the concentrated acid.

Offline lukas.stib

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Re: Synthesis of propionic acid by salt+acid
« Reply #7 on: April 15, 2022, 12:25:23 PM »
OK, thank you. I can't get propionic acid anywhere in the Czech Republic, so I wanted to try it from its sodium salt. I wanted it for esters, so maybe it would be more appropriate.

« Last Edit: April 15, 2022, 12:40:26 PM by lukas.stib »

Offline Babcock_Hall

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Re: Synthesis of propionic acid by salt+acid
« Reply #8 on: April 16, 2022, 09:26:31 AM »
One might be able to desalt a mixture containing sodium ions and an anion with a mixed-bed ion exchange resin.  I am not sure how practical this is.

Offline lukas.stib

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Re: Synthesis of propionic acid by salt+acid
« Reply #9 on: April 21, 2022, 02:31:54 AM »
And what about a mixture of propionic acid and water to dry some salt? Sodium sulfate?

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