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Topic: Removing boronic acids  (Read 8049 times)

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Offline nox

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Removing boronic acids
« on: May 02, 2012, 10:25:32 PM »
I'm running some Suzuki couplings and the best conditions (ones that consistently give >90% yields) that I've discovered require 2 equivalents of the boronic acid. The typical workup simply involves washing with brine and drying. I find that with this I typically end up with quite a bit of leftover boronic acid which accounts for maybe 30% if the crude weight.

Normally this isn't an issue but when I'm scaling up this becomes a nuisance, especially since I have to column the reaction (these reactions are always a bit messy). If I could somehow extract away the boronic acid during the workup that would really save me a lot of trouble. I'm thinking probably a basic wash (1M NaOH?) might do the trick, maybe also throw in some ethylene glycol? I'm no expert so if anyone has experience please do share!

Offline discodermolide

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Re: Removing boronic acids
« Reply #1 on: May 03, 2012, 01:29:46 AM »
I'm running some Suzuki couplings and the best conditions (ones that consistently give >90% yields) that I've discovered require 2 equivalents of the boronic acid. The typical workup simply involves washing with brine and drying. I find that with this I typically end up with quite a bit of leftover boronic acid which accounts for maybe 30% if the crude weight.

Normally this isn't an issue but when I'm scaling up this becomes a nuisance, especially since I have to column the reaction (these reactions are always a bit messy). If I could somehow extract away the boronic acid during the workup that would really save me a lot of trouble. I'm thinking probably a basic wash (1M NaOH?) might do the trick, maybe also throw in some ethylene glycol? I'm no expert so if anyone has experience please do share!


Have a look at this thread
www.chemicalforums.com/index.php?topic=57646.0;wap2
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Offline Doc Oc

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Re: Removing boronic acids
« Reply #2 on: May 03, 2012, 08:23:54 AM »
I always washed boronic acids out with NaOH.  If your product can survive it, you can definitely use that method.

Offline nox

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Re: Removing boronic acids
« Reply #3 on: May 03, 2012, 11:07:26 PM »
yeah just tried a 1M NaOH wash today. Seems like it got rid of most of the boronic acid since the baseline spot is pretty weak (I used to always see a strong baseline spot in these reactions).

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