Sciencemadness Discussion Board

Drying ethanol.

pepsimax - 16-5-2014 at 23:45

My 99.8% sigma ethanol bottle is about half full and has sucked a fair bit of water in. I poured 50ml into a dish last night and this morning there's a ml or two of slightly oily water. Would the usual MgSO4 treatment help? I tried once but it left a nasty brown tinge! However the salt was yellowed from baking it too long. Another thing, when making sulphate salts - adding a dash of this ethanol to the organic phase seems to help the acid mix much quicker. However my expected yield of product is larger and impure. It is probably sodium sulphate from trapped aqueus NaOH left from poor drying, but are there any common substances in the sigma reagent 99.8 that would salt out? Please pardon lack of paragraphs, phone lacks this function.

hissingnoise - 17-5-2014 at 01:03

The lack of paragraphs is eminently forgivable ─ but your having 99.8% sigma ethanol is an entirely different matter . . . ?


pepsimax - 17-5-2014 at 04:09

Ha, why so? Saw it for sale on an auction site, bought it. Stuff like that doesn't crop up often so I snapped it up at a steal. I'm happy to share at the cost of postage. :-)

[Edited on 17-5-2014 by pepsimax]

hissingnoise - 17-5-2014 at 04:20

Quote:
Ha, why so? Saw it for sale on an auction site, bought it.

It's envy ─ some find themselves distilling cheap vodka!

Tsk, tsk! You'll just have to distill from a desiccant . . .


pepsimax - 17-5-2014 at 04:30

Ah, heh sorry! Dropped my condenser the other day so was hoping simple drying agents may work. Are you after any? I can see if the guy has any more, think this may have been a special though. As above, i'm willing to share a small amount for postage money, if you're in the eu.

hissingnoise - 17-5-2014 at 09:03

Thanks P, I won't actually need ethanol for a while, but others here might . . .


jock88 - 18-5-2014 at 05:59


I seen a procedure way back in time regarding making super-dry ethanol.
First you distilled using a fractionating column. Then refluxed with a desiccant.
Then you refluxed the now very dry ethanol with some magnesium turnings and a pinch if Iodine. I think the Iodine 'activated' the turnings.
This stuff had very very little water. It would absorb water immediately from the atmosphere.

Pyro - 18-5-2014 at 07:21

There's a procedure in Vogel using Mg shavings activated with I2. you can get it to 99,95% like that.


organicchemist25 - 18-5-2014 at 14:59

I get great results from magnetically stirring ethanol with anhydrous MgSO4 for about an hour and then I set up in another flask with 1:1 ration of new MgSO4 and CaCl and distilled while having some MgSO4 in the receiving flask as well. It tested out to be 99.83%. Probably overkill, but it gets good results.

Then I just threw down and bought analytical grade.

[Edited on 18-5-2014 by organicchemist25]

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