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Topic: Removing residual water/methanol from an oily residue  (Read 3518 times)

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Offline lambda

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Removing residual water/methanol from an oily residue
« on: November 25, 2014, 01:06:07 AM »
How exactly would you remove residual water or methanol from a product that's an oily residue? My next reaction is pretty water sensitive and I'm not sure how exactly to remove any residual water. I tried looking into dissolving in benzene or toluene to form an azeotrope and rotovapping it off but the product doesn't dissolve in benzene or toluene so I don't think that's effective. The oil just sticks to the sides of the flask and doesn't really interact much. Not sure if trying the same thing with chloroform would work (since product does seem to be soluble in DCM).

Offline curiouscat

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Re: Removing residual water/methanol from an oily residue
« Reply #1 on: November 25, 2014, 02:38:24 AM »
CaCl2?

Offline orgopete

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Re: Removing residual water/methanol from an oily residue
« Reply #2 on: November 25, 2014, 09:58:54 AM »
I am suspicious about this description. I don't think you have a wet but otherwise pure product. I think you need to characterize your product further. I think the result will be that it needs purification.
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Offline lambda

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Re: Removing residual water/methanol from an oily residue
« Reply #3 on: November 25, 2014, 11:01:36 AM »
How would you use CaCl2? I know that can be used to dry solvents but I'm not sure how I would remove it if I were add it to the oily residue.

Also, why do you think it needs further purification? This compound was column purified and characterized by NMR. There was nothing in the NMR spectra that screamed "impure" to me, but I could be wrong. I was under the impression that some compounds are just oils rather than solid powders/crystals.

Thanks for your help guys.

Offline curiouscat

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Re: Removing residual water/methanol from an oily residue
« Reply #4 on: November 25, 2014, 01:00:38 PM »
I'd try adding an excess of high-purity CaCl2. It's pretty good at mopping up both dissolved & suspended moisture & usually will form a separate aqueous layer. You can filter out the solids & then  settle, phase separate & drain.

Use a lab centrifuge if needed.




Offline orgopete

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Re: Removing residual water/methanol from an oily residue
« Reply #5 on: November 27, 2014, 12:32:01 AM »

Also, why do you think it needs further purification? This compound was column purified and characterized by NMR. There was nothing in the NMR spectra that screamed "impure" to me, but I could be wrong. I was under the impression that some compounds are just oils rather than solid powders/crystals.


Before chromatography was used for purification, samples were recrystallized. I've had samples forming olis while forming crystals. I always took that as a sign my sample was not pure. The more pure it was, the less likely that would happen.
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Offline zsinger

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Re: Removing residual water/methanol from an oily residue
« Reply #6 on: November 30, 2014, 03:36:03 PM »
I am also suspicious.....what "oil".  Sounds like a safrole question to me.

 
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Offline Arkcon

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Re: Removing residual water/methanol from an oily residue
« Reply #7 on: November 30, 2014, 04:31:22 PM »
I am also suspicious.....what "oil".  Sounds like a safrole question to me.

Many reactions oil out when impure.  I don't see anything specific to illicit synthesis in this thread so far.  Well, except for your post.  ::)  We don't really have to worry about things, until we have to worry about things. :D
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

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