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Author: Subject: Ethanol/Acetone Azeotrope
Douchermann
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[*] posted on 14-1-2006 at 19:29
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.



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Douchermann
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[*] posted on 14-1-2006 at 20:03


Ah nevermind, I found out. It does not form an azeotrope



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[*] posted on 14-1-2006 at 23:08


Lol the acetone should evaporate out first.
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[*] posted on 16-1-2006 at 14:00


who is right?



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[*] posted on 16-1-2006 at 14:13


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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[*] posted on 16-1-2006 at 16:05


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...



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[*] posted on 17-1-2006 at 16:53


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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[*] posted on 12-9-2006 at 13:24
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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[*] posted on 12-9-2006 at 14:53


Acid/base catalyzed aldol(?) reaction maybe??

Could take a while...

Can't you just evaporate it?

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mericad193724
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[*] posted on 14-9-2006 at 12:58
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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[*] posted on 14-9-2006 at 18:17


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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[*] posted on 28-3-2011 at 08:08


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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[*] posted on 28-3-2011 at 08:51


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]




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[*] posted on 28-3-2011 at 10:33


How about refluxing the alcohol with NaOH to destroy the denatonium benzoate? Both by removing sodium benzoate and elimination of the quaternary amine.



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[*] posted on 28-3-2011 at 10:57


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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[*] posted on 28-3-2011 at 12:56


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




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[*] posted on 28-3-2011 at 17:46


Thank you. Sorry for not realizing the obvious.
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[*] posted on 28-3-2011 at 20:15


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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[*] posted on 3-7-2015 at 20:57


A fractional distillation will be necessary to separate the ethanol from acetone as their boiling points are so similar



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