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Topic: pKa-values in extraction  (Read 2694 times)

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Offline asa029

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pKa-values in extraction
« on: November 11, 2011, 12:34:27 PM »
Hi,

I have to compounds A and B, both soluble in ether that I would like to seperate on account on different pKa-values (chromotography is not an option). I want to wash either A or B away with extraction using appropriate basic salt solution that deprotonates only B. The pKa-values are around 9 and 11 for A and B, respectively.

Anyone have any suggestion for appropriate salts?
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Offline fledarmus

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Re: pKa-values in extraction
« Reply #1 on: November 11, 2011, 04:59:38 PM »
How could you deprotonate only B if the pKa value for A is lower than the pKa value for B? It seems to me that A would be deprotonated first...
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Offline asa029

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Re: pKa-values in extraction
« Reply #2 on: November 12, 2011, 03:42:00 AM »
Quote from: fledarmus on November 11, 2011, 04:59:38 PM
How could you deprotonate only B if the pKa value for A is lower than the pKa value for B? It seems to me that A would be deprotonated first...

Yes, sorry. Messed up my As and Bs:D I want to deprotonate A and not B!
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Offline fledarmus

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Re: pKa-values in extraction
« Reply #3 on: November 12, 2011, 10:41:06 AM »
Ah, that makes it much easier!  :) Now, what sort of concentrations would you see for protonated and deprotonated A and B if you have a pH of 7? 9? 11? 13?
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