Sciencemadness Discussion Board - Separation of solvents

Separation of solvents

TacosNitrate - 8-9-2016 at 04:59

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...

gdflp - 8-9-2016 at 05:35

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]

TacosNitrate - 8-9-2016 at 05:44

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]

XeonTheMGPony - 8-9-2016 at 06:41

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!)

gdflp - 8-9-2016 at 07:17

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.

Magpie - 8-9-2016 at 19:32

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?

DraconicAcid - 8-9-2016 at 19:46

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.

gdflp - 8-9-2016 at 19:57

Quote: Originally posted by Magpie

I thought the bisulfite adduct was only for aldehydes?

Nope, it works for both ketones and aldehydes. Relevant quote from the Purification of Laboratory Chemicals 6th edition entry for MEK :

Quote:

Purification as the bisulfite addition compound is achieved by shaking with excess saturated Na2SO3, 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 Na2CO3 solution and steam distillation, the distillate being saturated with
K2CO3 so that the ketone can be separated, dried with K2CO3, filtered, and distilled.

Interesting that they're using sodium sulfite instead of sodium bisulfite, but the addition compound is certainly stable.