Sciencemadness Discussion Board

separating solvents

andre178 - 4-2-2011 at 10:19


I would like to separate ethyl acetate from toluene, both solvents are pure, the etoac is roughly 5% of the toluene.

What is the best way to do this? I tried raising the temperature just slightly above the bp of etoac (77*C) but nothing happened. I have a rotovap and all the distillation apparati

thank you!

Ozone - 4-2-2011 at 13:11

Toluene does not appear to form an azeotrope with ethyl acetate (if it does, I can't find it easily, and it's not in Lang's). If you distill enough *toluene* (110.8°C) over, the EtOAc will come with it.

Or, I suppose we could over complicate by adding water, a trace of acid and following the two ternary azeotropes:

water : ethanol : toluene @ 74.4 °C @ 12% w/w water: 37 % ethanol:51 % toluene
water : acetic acid : toluene @ who the hell knows.

Wait...a minute. Was that 77°C at the still head, or in the liquid?


andre178 - 4-2-2011 at 13:17

it was the solution, the still head was 25. It seemed like a straight forward frac dist but it does not work

Ozone - 4-2-2011 at 13:58

That's what I thought. The *head* temperature needs to be at least 77°C before anything will come over. Wrap the column with aluminum foil. By the time you get toluene (head @ 110°C) your EtOAc should be gone.



andre178 - 4-2-2011 at 14:06

thank you, so to get this straight, the water bath temperature will be pretty high? i might even have to go on and use a flame?

Lambda-Eyde - 4-2-2011 at 14:09

You can't use a water bath for anything that boils at 100 degrees or higher... I thought that was obvious? Normally, water baths are used for substances with boiling points of less than 80 degrees. You have to use an oil/air/sand bath or a heating mantle.

andre178 - 4-2-2011 at 14:10

yes Lambda, EtOAc boils at 77.

Lambda-Eyde - 4-2-2011 at 14:17

Woops! I only read toluene (110)! My fault. :P

Anyways, wrap the column with mineral wool and aluminium foil. Don't use a flame when distilling flammable solvents!