isothiazolinone - 11-10-2016 at 13:41
Hi all, I have acquired some phosphorus pentoxide with the goal of using it as a dehydrating agent for ethyl acetate. I have already taken the
preliminary step of drying the ethyl acetate with sodium sulfate, but now im unsure what the appropriate amount of phosphorus pentoxide would be to
add to the ethyl acetate. I have 54 ml ethyl acetate, but Im more curious how much to add on like a generalized grams per ml type ratio. I know
phosphorus pentoxide to be quite a potent dessicant and its quite expensive so i want to make sure i use the appropriate amount.
Magpie - 11-10-2016 at 14:56
Since you have already dried the ethyl acetate I wouldn't think it would take very much P2O5, ie, a gram at most.
I have used it for drying acetone and chloroform before but just used what looked good. I had no rule of thumb other than "keep adding it until it
flows freely." You can read about this in Prepublication, "Preparation of PCl5."
[Edited on 11-10-2016 by Magpie]
DraconicAcid - 11-10-2016 at 17:31
And don't leave it in for very long. Phosphoric acid is likely to hydrolyze the ester.
unionised - 12-10-2016 at 11:34
Why use such an expensive drying agent for a solvent that can be dried by simple distillation?
Also, I rather suspect that you will get a messy transesterification- potentially leading to tetraethyl pyrophosphate (and lots of other things).
https://en.wikipedia.org/wiki/Tetraethyl_pyrophosphate#Toxic...
Frankly- it's a stupid way to dry the stuff