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Author: Subject: The Short Questions Thread (4)
sparkgap
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[*] posted on 19-6-2017 at 13:19


Quote: Originally posted by gluon47  
My school has given me the opportunity to do a few experiments in there lab. I noticed they had a bottle of anhydrous propionic acid, so I thought I might make a propionate ester.

I would like to try isopropyl propionate. Fischer esterification should work for making this ester right?

Would adding anhydrous magnesium sulphate to the reaction mixture during reflux help to increase yield?

Any advice would be much appreciated.


Fischer should work for both primary and secondary alcohols. Isopropyl alcohol is cheaper than propionic acid, so use that in excess. If you can use a Dean-Stark trap, do so; magnesium sulfate won't do much in those reaction conditions.

sparky (~_~)




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[*] posted on 19-6-2017 at 13:25


Quote: Originally posted by gluon47  


I would like to try isopropyl propionate. Fischer esterification should work for making this ester right?

Would adding anhydrous magnesium sulphate to the reaction mixture during reflux help to increase yield?



Yes, a Fischer esterification would occur. Considering you are already using anhydrous propionic acid and presumably 99% isopropanol, the use of magnesium sulfate during reflux would not materially affect yield. I have seen desiccants used after reflux and separation in order to remove the residual water, but not during reflux.

[Edited on 19-6-2017 by mesanaw]
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[*] posted on 19-6-2017 at 14:11


I don't think I'd put any desiccant in the reaction mixture itself, but you might want to put some in the reflux path: https://www.youtube.com/watch?v=Ah5ds_3s5BI

Magnesium sulfate might clump up if you put it in a Soxhlet and run wet solvents through it, so molecular sieves are probably better.




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gluon47
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[*] posted on 20-6-2017 at 01:17


Awesome, thanks!:). I wont use MgSO4



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gluon47
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[*] posted on 20-6-2017 at 21:34


Performed the reaction today on a 1/6 mole scale with 20% excess of isopropanol. It was interesting to smell the propionic acid. A lot like glacial acetic acid, but more rancid, I like it:).

Isopropyl propionate seems to have the characteristic sweet odour of most simple esters, but quite reminiscent of glue and slightly less sweet.

I'm going back to the lab next week for workup and purification. Can't wait!





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