Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: santacruz05 on April 08, 2005, 02:11:26 PM
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I'm by no means an experienced chemist, but i have some backround knowledge and schooling. Here is my problem:
I have two chemicals im trying to seperate, there boiling point, vapour pressure, density are all almost exactly the same. There only significant difference is there freezing point, but this is -25C and -40C and i've tried freezing one and straining the other, but it just turns it all to slush. Any assistance in this would be greatly appreciated.
The two chemicals are :
Pyrroline
Gamma-ButroLactone
Thanks
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15 degrees is going to be a bit small difference I think. Besides that would be a tough thing to do. Have you tried extractions?
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you tried chemical seperation? one of the substance could have a very strong affinity for another compound, while the other dont.
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Or you could try change them into derivatives that have different boiling temperatures or cristalise in different temperatures..
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I don't want to change them chemicals into derivatives, unless they can be changed back tho.
Also, how would I find out what Pyrroline might have an affinity to? where would this information come from?
Thanks for the help...
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Give us some more info about this Gamma-ButroLactone (besides that it's some rape drug.. ::))
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No, It's not a rape drug. It has a derivitive (GHB) that is a rape drug. The initial GBL has two purposes, one it is a sedative, widely used in China for people whom suffer from Insomnia and the other use is to help increase growth hormones and deep sleep body repair. It's a sleep-aid. The last but not least important use of this chemical, is it's ability to accelerate obsorbtion of another chemical through organic matter. When combined with some chemicals, it enhances the ability for that chemical to be obsorbed into the outter surfice of most organic matter, namely plants. I need that ability right there.
Needless to say it's nothing while still mixed with Pyrrolidine. N-Methyl-2-Pyrrolidine to be exact.
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If the only difference between properties of two organic compounds is their melting point, then you should try ZONE MELTING method of separation. It is wide used technology now days. For example :purification of naphtalene carried out by this route. I have never had opportunity to try it meself, but i am sure there are available laboratory and pilot plant apparatuses on a market. You can construct it by yourself as well. The main problem is going to be needs to operate at low temperatures. Properly built system can assure very hight level of purification of end products.
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In the Aldrich catalog, it indicates that 3-pyrroline boils at 90 C @ 748 mm Hg which would be ballpark 95 C at atmospheric pressure (760 mm Hg). gamma-Butyrolactone boils at 204 C. This should be an moderately easy distillation. If your naming is incorrect or Aldich is incorrect, column chromatography with monitoring by TLC (both should be UV active making it easy) is the most powerful separation method for quantities in the 1 g to 100 g region.
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In the Aldrich catalog, it indicates that 3-pyrroline boils at 90 C @ 748 mm Hg which would be ballpark 95 C at atmospheric pressure (760 mm Hg). gamma-Butyrolactone boils at 204 C.
According to you information a simple still would work. Unless the 2 compounds together change their boiling/freezing points (like salt in water). Just look online at how to make an alcohol still and adapt 1 of those to your purpose. You just need to be patient. If it is possible to distill; then, like you just stated, it would be easy. I've purified alcohol with a crude still.