Sciencemadness Discussion Board

toluene from thinner

gluon47 - 11-11-2015 at 21:11

I'm trying to extract toluene from a paint thinner. The thinner says it contains:

toluene 430g/L , acetone 135g/L , methyl isobutyl ketone (MIBK) 40g/L

The acetone won't be a problem to remove. I'll just add water and the thinner should separate into two layers: one containing acetone and water the other toluene and MIBK.

However, I'm stumped on the next step: separating toluene from MIBK.

Simple distillation won't work as the boiling point for toluene is 110.6 C and MIBK is 117-118 C. Too close.

I suppose fractional distillation would work but I don't have a fractionating column and I'm reluctant to buy one. I'd much rather find an easier way.

I was thinking, could I salt out the toluene from the MIBK or vice versa? If not, does anyone have any other ideas on how to separate these two solvents?

Thanks in advance,

gluon


JJay - 11-11-2015 at 22:18

It's pretty easy if you have some n-butanol. You can't separate toluene and MIBK with a column, BTW.

http://www.google.com/patents/US5250157

gluon47 - 11-11-2015 at 23:15

brilliant jjay!!! I don't have n-butanol but I know where I can get some. Guess I just need to find out what the boiling point for the n-butanol & MIBK azeotrope is then I'm sorted!

many thanks:)

JJay - 12-11-2015 at 01:01

Hey, thanks :) I don't know what it is, but I'm sure it isn't hard to find experimentally... it's quite likely published on the ACS azeotrope list, and it may be in the Lange or CRC handbooks... I don't know offhand.

[Edited on 12-11-2015 by JJay]

OneEyedPyro - 12-11-2015 at 03:16

MIBK is slightly soluble in water while toluene is almost completely insoluble.
Perhaps you could repeatedly agitate with hot water then decant until pure.

On another note, why not just go buy pure toluene?

gluon47 - 12-11-2015 at 12:36

Quote: Originally posted by OneEyedPyro  
MIBK is slightly soluble in water while toluene is almost completely insoluble.
Perhaps you could repeatedly agitate with hot water then decant until pure.

On another note, why not just go buy pure toluene?


Great idea:)

I guess that method has the advantage of not having to buy n-butanol. Do you have any idea on how to tell when all the MIBK has been washed off?

And to answer your question:
Where i live, toluene is completly unavailable to me. I can import it but getting it from thinner is a lot cheaper plus more fun.



Crowfjord - 12-11-2015 at 12:47

How about a bisulfite extraction?

Oscilllator - 12-11-2015 at 19:31

gluon47 you should check out NurdRages video on this topic. He extracts toluene from paint thinner that has a very similar composition to yours, and provides a clear explanation of how it all works.

https://www.youtube.com/watch?v=ddCuWX4vtOA

gluon47 - 12-11-2015 at 19:37

damn! just looked at the msds for the thinner and it also contains heptane:mad: any ideas on how I could get rid of the heptane?

It's highly insoluble in water just like toluene so washing isn't an option sadly.
I'm sorry to be of more nuisance.

@oscillator
thanks I've seen that nurdrage video. Sadly his thinner is easier to separate then mine. Nurdrage states that his thinner is MEK, methanol, acetone and toluene. Toluene is the only insoluble one






[Edited on 13-11-2015 by gluon47]

ave369 - 13-11-2015 at 06:30

Try fractional distillation. Heptane, IIRC, is more low-boiling than toluene. The difference in boiling points is about 10-12 Celsius, so you need a good fractionating column.

UC235 - 13-11-2015 at 06:41

You could use solvent extraction to remove the heptane. Of course, if you want the toluene as a solvent, this is ridiculous, but if you need a small amount as a reagent, DMSO is miscible with toluene but has poor solubility for heptane.

gluon47 - 13-11-2015 at 11:54

I do need the toluene as a solvent and so I guess I'll have to buy a fractionating column. Thanks for your great ideas peoples.

P.S do's anyone know if heptane and toluene form an azeotrope? cant find the answer on the internet

[Edited on 13-11-2015 by gluon47]

ave369 - 13-11-2015 at 14:10

I think a long Vigreux condenser will work as a fractionating column.