Author Topic: GAA via vinegar/AA single distillation?  (Read 2159 times)

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n00dle

  • Guest
GAA via vinegar/AA single distillation?
« on: August 08, 2004, 03:07:00 AM »
Vinegar/acetic acid (any % H2O) is placed into a distillation setup and castor oil is added to the soln.
The mixture is rotationally stirred to prevent the oil layer from being broken.

Pure acetic acid will distill over as glacial acetic acid is miscible with castor oil, however, water is not, therefore differentiating the contents via miscibility. (Consider using a drying tube to make sure it's dry. Water in the air above the tube may slightly reduce the purity of the acetic acid.)

Btw, castor oil is also miscible with alcohol, so this technique can be applied with ethanol to get anhydrous ethanol.

Benefits: Cheap. Easy. OTC. No fancy gear needed. If a stirring apparatus cannot be implemented into the oil, one could mix the oil and vinegar/AA, seperate the oil and distill the AA out of the oil directly. Anyone care to find faults?

Rhodium

  • Guest
Duh?
« Reply #1 on: August 08, 2004, 05:41:00 AM »
What makes you think that a lower-boiling component of a two-phase mixture wouldn't distill before a higher-boiling component?

If you put dichloromethane and water in a flask, don't you think the DCM would distill over before the water even if the water layer is on top?


moo

  • Guest
Reminds me of steam distilling!
« Reply #2 on: August 08, 2004, 09:20:00 AM »
Reminds me of steam distilling!


n00dle

  • Guest
Rhodium, it has nothing to do with the ...
« Reply #3 on: August 08, 2004, 11:23:00 PM »
Rhodium, it has nothing to do with the -Placement- of the layers it has to do with miscibility of the components.

For starters, simply adding castor oil and removing that layer and distilling should suffice.
Second of all, one could get a cooking pot and insert an element into the pot so that it is only heating up the oil layer. Acetic acid will migrate and be distilled out, leaving the water, colder than the oil layer, behind.

Rhodium

  • Guest
I'm still not any wiser...
« Reply #4 on: August 08, 2004, 11:31:00 PM »
Then, reading the msds of castor oil and finding its also miscible with castor oil, the same properties will exhibit.

Huh?


n00dle

  • Guest
Err, i meant acetic acid.
« Reply #5 on: August 08, 2004, 11:37:00 PM »
Err, i meant acetic acid.

I see where you're coming from, that the acetic acid wont distill easily because its BP is higher then that of water. But by moving the heat source to the oil layer, -or-easier still, dumping castor oil into vinegar/acetic acid, then stirring so that some of it becomes miscible then removing the castor oil/acetic acid layer and distilling that layer should yeild castor oil in the first flask and GAA in the second flask..

Nicodem

  • Guest
Extracting acetic acid from dilluted solutions
« Reply #6 on: August 09, 2004, 02:04:00 AM »
Extracting acetic acid from dilluted solutions (the most concentrated vinegar in my country is 9%) is very unefficient even with solvents that have a reasonably good partition coeficient (like ethylacetate) and requires a continous extraction. I seriously doubt that castor oil or any other "oil" would take up a useful amount of acetic acid, but you are free to try and tell as all about it. Hower you can forget the idea of distiling AA from a two phase system like you described it. The oil is not going to hold back the water wapors - the water at the phase boundary would start to boil as the oil would reach temperatures above 130°C that would be needed to evaporate the small concentrations of AA and water from its phase. There is no way to keep the water bellow its b.p. as liquids are good heat conductors and even bellow 100°C the wapors would still apreciably diffuse trough the imobile oil layer.


n00dle

  • Guest
Nicodem as soon as SWIM gets some castor oil...
« Reply #7 on: August 10, 2004, 12:28:00 AM »
Nicodem as soon as SWIM gets some castor oil SWIM will attempt  it. As far as SWIM sees, as the msds states it's miscible with AA and not water, then adding castor oil should find an equilibrium of miscibility with the oil and water. Eg, if you have X amount of AA in water, and you add the same amount of oil, you should get half of X per layer. Yes?

Nicodem

  • Guest
No
« Reply #8 on: August 10, 2004, 08:51:00 AM »
Eg, if you have X amount of AA in water, and you add the same amount of oil, you should get half of X per layer. Yes?

Where did you get such an idea from? Like I told you the distribution of X in both solvents depend on the partition coeficient (=distribution coeficient) of the particular biphasic system. Read and see the table in

http://www.cheresources.com/extraction.shtml

. As you can see there, the best solvent would bee n-butanol or ethylacetate and the worse hexane. You can aproximate the castor oil to bee a better solvent for AA than hexane but worse than toluene. Therefore you can expect the castor oil to have the partition coeficient roughly about 0.04. Use the equation for the distribution and see how much AA you can extract from a 9% vinegar with an equal amount of castor oil. (I don't even have to calculate it to know its useless)

Anyway, are you saying that where you live you can't buy acetic acid? Not even the 80% AA? Incredible.