Hi everyone,
I'm trying to do a cation exchange using Dowex50 and have little experience with this. I have tried several times to repeat a literature procedure in which a column is packed with Dowex H+ form, an aqueous solution of a sodium salt is loaded and the column eluted with water. The problem is that I retain a lot of the sodium. I have doubled the amount of Dowex to little effect. Now my question would be: can I also just put the Dowex into an Erlenmeyer flask, add my aqueous solution, stir it all for say half an hour and then add this mixture onto a small Dowex column? Do you think this might make sense?
Please forgive me for being unspecific, I'm not allowed to publicly speak about my research.
Thank you
NIko
Using ion exchange is an equilibrium process. So it depends on the cation on the resin on how well sodium will exchange with it. Normally to beat the equilibrium one passes the solution over a column of the resin so there are repeated exchanges rather than just putting it into the solution. Rather than doing the initial soaking, then a small column, a larger column would be better. Your idea might work, but it would depend on how much sodium is left after your initial soaking.
Hi Niko Sebastian Willem Lindlar , did your column work? I'm trying to exchange N(Bu)4 cation to NH4, but I'm struggling with the remaining N(Bu)4 cation in my product. In my case, I loaded the Dowex resign with 1M solution of NH4Cl and washed the Cl- from the resin with water. I tried to add and stir my product with the resin (NH4+ form), but 1H NMR showed the presence of N(Bu)4 in my product. I'm considering running a column to see if I can exchange it, but I don't know how much resin I need.
You might be able to guess how much resin to use based on how much N(Bu)4 was left after you stirred it. Given the # of moles of resin you used and how much exchanged you could calculate a rough equilibrium constant for the exchange. From that you could figure how many exchanges were needed and size the column accordingly.
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