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Topic: Triazole workup problem  (Read 4233 times)

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Offline The Guy

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Triazole workup problem
« on: March 19, 2014, 01:50:24 AM »
I am trying to synthesis the attached molecule. Starting material: CuI, NaN3, 2-bromothiophene, Propargyl alcohol, ligand(dimethyleethylenediamine) DMSO as rxn media.
Work up: add Sat NH4Cl, and DI Water, then extract with EtOAc
I end up with emulsion look too similar to:
It is even worse, but look similar even in color.
When I extract with THF the emulsion became less issue, but I end up extracting different substance.
Why it looks so bad with EtOAc? Even Brine has no effect on that. The emulsion is like a sponge and it spread all over the organic layer, unless the organic layer 10 times more than the aqueous layer, I would have some room to extract something each time.
Also, each time the aqueous layer smells like EtOAc, it always has alot of the solvent, I am afraid the product too.
Any suggestion?
« Last Edit: March 19, 2014, 02:12:46 AM by The Guy »

Offline discodermolide

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Re: Triazole workup problem
« Reply #1 on: March 19, 2014, 02:27:18 AM »
How much DMSO are you using?
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Offline The Guy

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Re: Triazole workup problem
« Reply #2 on: March 19, 2014, 09:53:02 AM »
2mL  :)

Offline discodermolide

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Re: Triazole workup problem
« Reply #3 on: March 19, 2014, 10:41:52 AM »
Do you filter the reaction mixture first?
Try a different solvent for extraction, isopropyl acetate or even dichloromethane
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Offline The Guy

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Re: Triazole workup problem
« Reply #4 on: March 19, 2014, 02:59:14 PM »
Do you filter the reaction mixture first?
Try a different solvent for extraction, isopropyl acetate or even dichloromethane
If I did, the filter funnel will be clogged, and when I used vacuum filtration everything come it as it is.
I did try chloromethan, the desired product has low solubility in it, too low.
I will try isopropyl aceetate, I hope we have it in lab.

Thanks for your help.

Offline discodermolide

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Re: Triazole workup problem
« Reply #5 on: March 19, 2014, 03:07:55 PM »
You have an alcohol, try and acylate it first then extract. This will make it more soluble. You can then get it out pure as the acetate.
Hydrolyse the acetate.
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Offline 408

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Re: Triazole workup problem
« Reply #6 on: March 19, 2014, 07:16:36 PM »
Filter through kieselguhr with vacuum.  Rinse kieselguhr with lots of EtOAc and water.  Continue as normal.

Offline The Guy

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Re: Triazole workup problem
« Reply #7 on: March 20, 2014, 09:44:35 PM »
You have an alcohol, try and acylate it first then extract. This will make it more soluble. You can then get it out pure as the acetate.
Hydrolyse the acetate.
You mean more soluble in CH2Cl2?

Offline The Guy

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Re: Triazole workup problem
« Reply #8 on: March 20, 2014, 09:52:05 PM »
Filter through kieselguhr with vacuum.  Rinse kieselguhr with lots of EtOAc and water.  Continue as normal.
I am not sure if the reagents has something to do with the emulsion, however, I will try your suggestion.
I really appreciate your help guys

Offline 408

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Re: Triazole workup problem
« Reply #9 on: March 20, 2014, 10:01:06 PM »
Fine suspended particles often make for horrible emulsions.  Removing them helps as long as you make sure to remove any stuck product with lots of washes. 

Offline The Guy

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Re: Triazole workup problem
« Reply #10 on: April 13, 2014, 04:06:06 PM »
I want to thank your for your golden comment. After vacuum filtration through Celite the emulsion and the whole extraction process has been resolved, with EtOAc the emulsion still exist but a little things that I could overcome, with other solvents it disappear.

Thank you for helping me.

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