ChemicalSolution (Hive Bee)
04-11-02 07:07
No 295362
      etOH/H2O/toluene azeotropic distillation  Bookmark   

Here's what Julia knows..

H2o/toluene-- 85C, 20% H20
etOH/toluene/water-- 75C ???composition
etOH/toluene--- 76.7C 68% etOH.
etOH/water-- 78.3C 95% etoh..

Since the etOH/toluene/water is the first azeotrope to distill, does anyone know the % composition of each component?

Julia
 
 
 
 
    terbium
(Old P2P Cook)
04-11-02 07:19
No 295365
      Ethanol/toluene/water : 37/51/12 and boiling at ...  Bookmark   

Ethanol/toluene/water : 37/51/12 and boiling at 74.4. Seems too close to the b.p. of ethanol (78.5) to be of much use.
 
 
 
 
    Chromic
(Hive Addict)
04-11-02 08:20
No 295379
      Breaking the azeotrope  Bookmark   

Use ~20 stages and a R.R. of about 1.5 and you won't have a problem making the separation. After running it through a distillation, separator and another distillation the water content is less than 0.1%, toluene content ~2%. Use google for more info.
 
 
 
 
    hest
(Hive Bee)
04-11-02 09:52
No 295415
      Wow ChemicalSolution You are now jumping into the ...  Bookmark   

Wow ChemicalSolution
You are now jumping into the dreful part of chemistry (the physical chemistry) It can all bee solved vith some (not cso complicated) math, but personal I hate it.
From my practical eksp. the usual wathercontent in methanol (when used as an azeotrop) is 3-5%.
Some years ago (15?) the commercial way to produce EtOH(99%) was the azeotropi destilation of benzene and wather, I guess there was a reason that they used benzene(with a lower boiling point) instead of toluene.
 
 
 
 
    Mountain_Girl
(Hive Bee)
04-11-02 10:09
No 295417
      Phys chem & industrial drying of EtOH  Bookmark   

Hest: I'm the opposite - phys chem is my strong point.

"From my practical eksp. the usual wathercontent in methanol (when used as an azeotrop) is 3-5%"
I assume you meant EtOH ?

AFAIK the market for toluene/benzene goes through phases. Sometimes benzene is the more valuable product, sometimes it's toluene and plant production is adjusted accordingly. This may have some influence on which compound to use for dehydrating EtOH industrially.
These days Benzene is used less due to its toxicity, being replaced with Cyclohexane, Toluene and more recently, Propylene Glycol.
 
 
 
 
    Sunlight
(Pioneer Researcher)
04-11-02 16:22
No 295483
      olunen/water  Bookmark   

I've beeing using to xtallyze 2-3 gr. batches with toluene (dried and filtered) then added IPA/aq HCl and then evaporating almost all the solvents with the aspirator. It works fine, finally the xtals are taken out with acetone. I was thinking about the IPA/toluene/water azeotrope, that seems better to remove water then methanol or ethanol, but don't now the exact temp. It works as well at room pressure, but the aspirator keeps always the temp < 30 - 40 C.
It has been for me a good finding to make the salt if small amounts without loss of product.