Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: CopperSmurf on March 07, 2013, 08:57:36 AM
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Just wondering if anyone has a good idea on how to "clean" pyrrole liquid. It should look clear and colourless but it looks yellow. I tried running it through a small alumina column and it still looks somewhat yellow. I'm aware that it is moisture, air and light sensitive. Is there another way to make it clear so that it is useable?
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Just wondering if anyone has a good idea on how to "clean" pyrrole liquid. It should look clear and colourless but it looks yellow. I tried running it through a small alumina column and it still looks somewhat yellow. I'm aware that it is moisture, air and light sensitive. Is there another way to make it clear so that it is useable?
Is there nothing in something like Perrin and Armarego? What does the NMR look like? What are you planning to do with it?
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I used to use pyrrole often as a precursor to porphyrin synthesis. It does tend to turn yellow over time due to light or oxygen induced polymerization. I don't recall purifying it unless it was really bad, because those impurities could be removed during purification of our product. If purification was necessary, we usually distilled it, I think under nitrogen atmosphere.
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I'm not sure what Perrin and Armarego are. I do not have access to NMR. I will be using it as part of a synthesis procedure for someone else.
Would the heat from distillation make it worse or did you (Corribus) do it under reduced pressure?
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Hi, I was making conductive polymers from simple heterocycles, and all I know about your question is that there is no problem to perform a distillation of pyridine, as I actually had to purify it. Compare it with pyrrole, maybe it's worth trying.
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To the opening poster, honestly it's been over a decade since I did that kind of purification. I couldn't tell you how we distilled it. I don't remember it being too much of a pain, so I don't think it entailed a very elaborate set up. I do still keep in touch with my old lab - I can ask if it'd be helpful.
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You can distill it, but you need to do it under an inert atmosphere (N2 or Ar).
This book (http://books.google.co.uk/books?id=PTXyS7Yj6zUC&pg=PA428&lpg=PA428&dq=distillation+of+pyrrole&source=bl&ots=ZwRX7Evwfx&sig=C3SZ4hfoLRDhy8xNi63E1g7kMyM&hl=en&sa=X&ei=Naw5UZnvHZPc4QTOl4HICg&ved=0CF8Q6AEwBjgK#v=onepage&q=distillation%20of%20pyrrole&f=false) mentions distilling from CaH2 at the bottom of p428, but not in much detail. It looks like a pretty standard distillation.
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OMG...just distill it under N2 or argon and thats it. But be aware that it will be colored very soon! Store it dark and cold (0°C). Every rxn I performed with pyrrole I just took a fresh bottle from Aldrich and everything went fine. Of course, pyrrole is giving always black, tar-like by-products.