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Topic: Flash chromatography  (Read 2939 times)

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Offline digchick21

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Flash chromatography
« on: September 11, 2012, 10:43:41 AM »
I was wondering how i can remove the silica that has got into my sample after i have already done Flash chromatography on it?

Offline synthon

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Re: Flash chromatography
« Reply #1 on: September 11, 2012, 10:49:33 AM »
Filter it out.  If the silica got there by using a very polar solvent, then evaporate the solvent, resuspend in a less polar solvent, then filter.  If some silica just found its way into your sample, then just filter.

Offline digchick21

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Re: Flash chromatography
« Reply #2 on: September 12, 2012, 04:11:51 AM »
Thanks a bunch  :)

Offline digchick21

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Re: Flash chromatography
« Reply #3 on: September 12, 2012, 09:14:14 AM »
Is that just with ordinary filter paper?

Offline IsotopeBill

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Re: Flash chromatography
« Reply #4 on: September 12, 2012, 12:40:16 PM »
Typically a fine grade; you may also want to use a filter aid such as Celite (use a high-quality filter aid).  Aldrich sells disposable filter units that attach to the end of a syringe:  you put your solution in the syringe, the filter unit on the end of the syringe, and force the solution through the filter (only good for small volumes).  Here's the web ad:
http://www.sigmaaldrich.com/catalog/product/sigma/z358282?lang=en&region=US
An inexpensive alternative to the syringe filter is to us a pasteur pipet:  pack a small piece of e.g. Kimwipe, followed by cotton, glass wool, and/or celite, add your solution and force it through with a bit of pressure from the nitrogen line

Offline Doc Oc

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Re: Flash chromatography
« Reply #5 on: September 13, 2012, 08:41:49 AM »
One very important question that hasn't been asked, what physical state is your product?  Solid?  Oil?  What solvent is it soluble in?

Without knowing any more, I would dissolve your product in an organic solvent (not MeOH).  That should give a suspension of the silica.  Depending on how much you have, you can either put a cotton plug in a Pasteur pipet and run it through that, or use a Buchner funnel (regular filter paper is fine).

Offline digchick21

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Re: Flash chromatography
« Reply #6 on: September 14, 2012, 07:11:57 AM »
My products is an oil, soluble in most solvents i have been using dichloromethane. With the solvent evaporated off i have about 3g of product, so i guess a Buchner funnel is best.

Offline Doc Oc

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Re: Flash chromatography
« Reply #7 on: September 14, 2012, 07:46:31 AM »
I would agree with that.  Alternatively, if you have a glass funnel, you can just put a small cotton plug in it and use that.

Offline digchick21

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Re: Flash chromatography
« Reply #8 on: September 14, 2012, 10:47:14 AM »
Thanks a lot, i am now silica free! :D

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