[lukas.stib]

Hi chemists,
I want to make propionic acid from propionates. I originally wanted to use sulfuric acid, but it is very strong (dehydrates the propionate), then I wanted to use phosphoric acid as an 85% solution. However, I would not have concentrated propionic acid (85%). I want to ask you, could I use p-toluenesulfonic acid with propionates? I believe it is not strong and dehydrating as sulfuric acid and I should get concentrated propionic acid. I just don't know the procedure, both substances are solid, so mix to a mixture and just heat?

Thank you. Lukáš S.

[Hunter2]

You can dilute the sulfuric or the phosphoric and later, after adding to the Propionate do an Destillation. The boiling point of propionic acid is 141 ° C.
If toluensulfonic acid is a better choose I dont think so.

[Aldebaran]

Bear in mind that propanoic acid forms an azeotropic mixture with water which boils at about 99°C.
It can be further concentrated by various extractive techniques which can be found on line.

[Hunter2]

Even better need not so high temperature  then.

[lukas.stib]

Thank you very much. Can I dry a mixture of water and propionic acid using anhydrous sodium sulfate? It is said that propionic acid can be concentrated in this way.

[Aldebaran]

The solution would contain a high  proportion of water. I think you would be better off using an extraction method first then when you have a high concentration of the acid it might lend itself to drying depending on what extraction method you use.
However I’ve not personally carried out this procedure with propanoic acid so I can’t give advice from personal experience.