TacosNitrate
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Separation of solvents
Ok, so i recently received 10 bottles of no-acetone nail polish remover, and they say to contain about 15% isopropanol, 10% ethanol, 35% butanone
(methyl ethyl ketone) and 40% water.
Every bottle has 250 ml of product, so in total i have 2 and a half liters of mixed solvents.
The things that i'm most enterested in recovering from this are the butanone and the isopropanol, and i thought that the extraction would be a fun
exercise, but i've encountered some problems.
The first thing that i did was to remove the water using a salt that is only soluble in it, saturating the water present in the solvent with that salt
so that about 90% of the other components would separate from the mix, but there come the problems:
I can continue with this method obivously, and the purify the products by fractional distillation, but i cannot find anything that is only soluble in
butanone alone, neither in isopropanol, neither in ethanol... i mean: there is CERTAINLY something soluble in just one of those solvents and insoluble
in the others, but internet just won't let me find it!!!
If some of you could help me out i'd be reeeally happy
Also
I chosen not to do the fractional distillation righr away because, you know, azeotropes and stuff..... and a very bad chinese thermometer...
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Texium
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Thread Moved
8-9-2016 at 05:13 |
gdflp
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I would separate the butanone by forming the bisulfite adduct. I'm not sure if this adduct is soluble in either of those alcohols, so if you don't
see the adduct precipitate in substantial quantity when you add the bisulfite solution, I would distill off the alcohols and the adduct should
precipitate. Separating ethanol and isopropanol will be tougher if you're not willing to fractionate it. There shouldn't be an azeotrope between
those two, so distillation is the way to go.
EDIT : Not sure how that picture got attached, removed now.
[Edited on 9-8-2016 by gdflp]
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TacosNitrate
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Thank you very much pal! I know that i can separate the two alcohols by fractional distillation, but unfortunately i already tried this method and it
just won't work, because it doesn't seem to separate even when the mixture is cooled....
Is there any other way to separate the methyl ethyl ketone?
Also, the butanone forms two very annoying azeotropes with both alcohols, that will also make the adduct precipitation process much more difficult,
because the adduct is soluble in ethanol and the first azeotrope by boiling point is the butanone-ethanol mix ( if i chose to distill it)
[Edited on 8-9-2016 by TacosNitrate]
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XeonTheMGPony
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the usage of vacuum is handy in disrupting zeotrops (If a true azeotrop you can't separate them as they behave as a single fluid!)
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gdflp
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Quote: Originally posted by TacosNitrate  | Thank you very much pal! I know that i can separate the two alcohols by fractional distillation, but unfortunately i already tried this method and it
just won't work, because it doesn't seem to separate even when the mixture is cooled....
Is there any other way to separate the methyl ethyl ketone?
Also, the butanone forms two very annoying azeotropes with both alcohols, that will also make the adduct precipitation process much more difficult,
because the adduct is soluble in ethanol and the first azeotrope by boiling point is the butanone-ethanol mix ( if i chose to distill it)
[Edited on 8-9-2016 by TacosNitrate] |
Once you have the butanone adduct, there is no longer free butanone in the solution. You can thus distill the alcohols off without fear of an
butanone-alcohol azeotrope coming over. Distilling the adduct with an acid will regenerate the pure butanone, which can then be purified by
distillation. A quick search of the forum reveals that attempting to separate ethanol and isopropanol may not be worthwhile, there are a few previous
threads on this topic.
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Magpie
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MEK is a methyl ketone and therefore it should be possible to make a haloform out of it. This may be separable from the alcohols.
I thought the bisulfite adduct was only for aldehydes?
The single most important condition for a successful synthesis is good mixing - Nicodem
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DraconicAcid
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| Quote: Originally posted by Magpie | MEK is a methyl ketone and therefore it should be possible to make a haloform out of it. This may be separable from the alcohols.
I thought the bisulfite adduct was only for aldehydes? |
That would convert it to propanoate, and make it separable from the other solvents, but he's hoping to keep the MEK.
Actually, under haloform reaction conditions, the isopropanol would probably oxidize to give acetone (which would then merrily continue to give
haloform and acetate), and the ethanol would probably also oxidize.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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gdflp
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Nope, it works for both ketones and aldehydes. Relevant quote from the <b>Purification of Laboratory Chemicals 6<sup>th</sup>
edition</b> entry for MEK :
| Quote: | Purification as the bisulfite addition compound is achieved by shaking with excess saturated Na<sub>2</sub>SO<sub>3</sub>,
cooled to
0°C, filtering off the precipitate, washing with a little ethyl ether and drying in air; this is followed by
decomposition with a slight excess of Na<sub>2</sub>CO<sub>3</sub> solution and steam distillation, the distillate being
saturated with
K<sub>2</sub>CO<sub>3</sub> so that the ketone can be separated, dried with
K<sub>2</sub>CO<sub>3</sub>, filtered, and distilled. |
Interesting that they're using sodium sulfite instead of sodium bisulfite, but the addition compound is certainly stable.
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