Sciencemadness Discussion Board

DMSO separation

X-321 - 24-1-2007 at 08:35

Hi everybody,

How could I separate ethyleneglycol from DMSO?

EG bp = 197.3 ºC
DMSO bp = 189 ºC

Thank you.

[Edited on 24-1-2007 by X-321]

Ozone - 24-1-2007 at 11:48

Other relevant physical property:

The melting point for DMSO is 18.5°C and Ethylene glycol melts at -12.9°C.

Give that a shot,

O3

X-321 - 24-1-2007 at 12:34

Thank you, O3.

BromicAcid - 24-1-2007 at 17:14

The boiling points are fairly close to separation by boiling might be very difficult. However there is an azeotrope between ethylene glycol and toluene or xylene. This boils lower than ethylene glycol itself, somewhere in the neighborhood of 120ish. This might work to get ride of your ethylene glycol from the mixture.

Ozone - 24-1-2007 at 18:41

o-xylene, I think. You will also chase out whatever water you may have (and you *will* have some in this mixture, unless you have distilled it with a Dean-Starke trap onto molecular sieves). But--Have you ever smelled boiling DMSO, expecially if a drop gets into your heating mantle. Good stuff.

Some Data:

Toluene chaser: 110.1°C, but 97.7% of the azeotrope is toluene
o-xylene chaser: 135.7°C, but 93.1% will be xylene.

Following this, It looks like tedious removal of solvent.

Best of luck,

O3

BromicAcid - 24-1-2007 at 19:01

Maybe salt it out? DMSO dissolves a number of ionics fairly well and I don't think ethylene glycol compares. Might result in a phase separation and a simple distillation might give the product?

Ozone - 24-1-2007 at 19:23

@X-321, what proportion of each is present in your mixture, viz. how quantitative does the separation have to be?

O3

X-321 - 25-1-2007 at 03:54

Quote:
Originally posted by Ozone
@X-321, what proportion of each is present in your mixture, viz. how quantitative does the separation have to be?

O3


1. The molar proportion DMSO/EG = 20/1.

2. Technical grade for EG is ok and the DMSO doesn´t mater since it would be reused many times for the same purpose.

unionised - 25-1-2007 at 11:10

At that ratio freezing the stuff and pouring off the EG (with some loss of DMSO) will work quite nicely. It's also a way to remove water etc from DMSO, Acetic acid etc

Ozone - 25-1-2007 at 16:32

That's where I was going with the Tm's :D. I have not used this method with ethylene glycol, but have used it to remove, as you say, just about everything else (although, to dry, I still prefer to re-distill over mol sieves afterwards).

Cheers,

O3

Oh, this can easily be done with an ice-salt bath and a thermometer; no worries.

[Edited on 26-1-2007 by Ozone]