Douchermann
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Ethanol/Acetone Azeotrope
Hey, I was wondering if ethanol formed an azeotrope with acetone because I had purchased a bottle of ethanol based rubbing alcohol. The extra
ingredients in it were acetone, water, denatonium benzoate and methy isobutyl ketone. The last 3 can easily be seperated because of boiling points
which I have done. I did not fraction it in the beginning because I don't have a thermometer adapter for my distilation rig (its the pellet lab) so I
couldn't monitor the temperature or antying. I'll redistill it and watch it more closely next time though. I'm just wondering if its worth my
worries.
It\'s better to be pissed off than to be pissed on.
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Douchermann
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Ah nevermind, I found out. It does not form an azeotrope
It\'s better to be pissed off than to be pissed on.
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ADP
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Lol the acetone should evaporate out first.
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alabama
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who is right?
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garage chemist
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Acetone, MIBK and denatonium benzoate are just denaturants and are present in no larger amount than about 2%.
All the Ethanol (94% vol.) sold as cleaner, stove fuel etc... where I live has approximately this composition, with MEK in place of MIBK and Acetone.
By dissolving 5% NaOH in it and refluxing for half a day, the acetone and MIBK polymerise and can be separated much more efficiently by distillation
(leave about 10% of the original liquid volume as residue).
The resulting Ethanol is almost pure enough to drink (I tasted it and it only burned and wasn't bitter like before).
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Taaie-Neuskoek
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Isn't the ethanol contaminated with methanol or pyridine??? That is usually used, and both of them are not very easy to get rid of...
Never argue with idiots, they drag you down their level and beat you with experience.
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Fleaker
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I don't think they'd use pyridine for that seeing how prohibitively expensive it is (from what I've seen though) but I'm nearly certain that methanol
is the main denaturant used. A small percentage of MeOH would be somewhat safe to drink (wine and beers have a bit of MeOH and other higher alcohols),
but I guess the purity required depends on what you plan to do with it.
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mericad193724
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OTC 70% EtOH purification
I purchased a bottle of Ethyl Rubbing alcohol. It is 70% EtOH by volume also containing Acetone, Methyl Isobutyl Ketone, Water, and Denatonium
Benzoate.
The amount of acetone is probably 10 percent by volume.
I expected the liquid to boil at 56C, acetone's boiling point, but the still head jumped to 78C before starting to boil, so I have a mix of acetone
and ethanol, probably a bit of H2O.
How can I separate the acetone without having to reflux. Does anything react with it to make it easy to separate out?
thanks
Mericad
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12AX7
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Acid/base catalyzed aldol(?) reaction maybe??
Could take a while...
Can't you just evaporate it?
Tim
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mericad193724
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BINGO!
Ok...I think I got it!
I can add NaOH to the Acetone/EtOH to make sodium ethoxide which is insoluble in acetone. Since it is insoluble you can just decantate the acetone and
dry the powder. (pure Sodium ethoxide)
then add HCl to neutralize the Ethoxide into ethanol and NaCl. From this a simple distillation should yield 95% EtOH 5% H2O.
C2H5NaO + HCl -> C2H6O + NaCl
Will it work?
Mericad
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not_important
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| Quote: | Originally posted by mericad193724
Ok...I think I got it!
I can add NaOH to the Acetone/EtOH to make sodium ethoxide which is insoluble in acetone. Since it is insoluble you can just decantate the acetone and
dry the powder. (pure Sodium ethoxide)
then add HCl to neutralize the Ethoxide into ethanol and NaCl. From this a simple distillation should yield 95% EtOH 5% H2O.
C2H5NaO + HCl -> C2H6O + NaCl
Will it work?
Mericad |
If you have 70% EtOH and maybe 5% ketones, and 25% water, you are not going to get NaOEt ppting out. The equalibrium NaOH + EtOH <=> NaOEt + H2O
is on the NaOH+EtOH side, you could force it if you had a good deal of acetone and not much EtOH but not when the alcohol is the major component. You
could dump in a truckload of NaOH to drive it to the alkoxide side, but you'd need a large excess of NaOH - it would be the major part of the solids.
And the denatonium benzoate will go with the hydroxide/ethoxide.
The ketones are going to condense just sitting there with strong NaOH, refluxing simply speeds it up. On the other had, what's hard about refluxing?
This is low temperature, you could do it in a large glass bottle sitting in a water bath, and a homebrew condenser; just warm the bath up slowly and
ordinary glass bottles will take it.
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jamit
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Has anyone purified 70% ethyl rubbing alcohol. As noted above by the original post there are denaturants like acetone, MIBK and denatonium benzoate.
How do you get rid of these denaturants and get a relativly pure ethyl alcohol of 95%?
Has anyone of you try distilling it? What was the temp, and what comes over?
Any help would be appreciate before I try it using simple distillation.
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Arthur Dent
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Well it's a bit difficult to separate denaturants without a good fractional distillation apparatus (so it's not considered and taxed as a drinkeable
product, they make it hard for that reason), and if I recall what i've been explained once, the denatonium Benzoate, also known as Bitrex, is very
hard to separate from Ethanol and even in extremely small quantity in the alcohol, makes it bitter as hell ant totally undrinkeable. But for chemical
purposes, that's not a problem... 
Robert
[Edited on 28-3-2011 by Arthur Dent]
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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mr.crow
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How about refluxing the alcohol with NaOH to destroy the denatonium benzoate? Both by removing sodium benzoate and elimination of the quaternary
amine.
Double, double toil and trouble; Fire burn, and caldron bubble
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Bot0nist
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Denatonium benzoate is a bitterant right? Why is it in all the supposed 100% acetone I buy. Do people try and drink it too?
[Edited on 28-3-2011 by Bot0nist]
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Arthur Dent
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Bitrex is used in any and all dangerous liquid household products where an infant or an animal might ingest because its not offensive and pungent like
ammonia or bleach. Acetone and ethylene glycol-based windshield washer fluid are good candidates.
Any creature would spit out the liquid instantly because of the horrible taste.
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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Bot0nist
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Thank you. Sorry for not realizing the obvious.
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jamit
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ok I've tried the distillation of 70 CVS rubbing ethyl alcohol. As I started boiling it (did not measure temp) using a simple distillation, there was
as definite acetone smell. What I'm confused is that I was not able to separate the ethyl alcohol from acetone. It seems like the smell of acetone
was there from beginning of the distillation to the end.
I'm assuming that acetone which boils around 56C should come over first then followed by ethyl alcohol. However, it seems that the acetone smell was
there from the beginning to the end of the distillation process.
Am I doing something wrong? Anyone have similar problems? Any suggestions???
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The Chemistry Shack
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A fractional distillation will be necessary to separate the ethanol from acetone as their boiling points are so similar
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