[marthaj]

Hi Friends
Please, some body can tell me what it is the role of sodium carbonate in the coupling reactions using dcc/HOBt.
Most of the papers mention the  use sodium carbonate to isolate the products. Please , help 

[Doc Oc]

A lot of amino acids in peptide couplings are sold as HCl salts, which makes them more difficult to use in peptide couplings (if not impossible).  Base is typically added to remove this acidic proton and re-activate the amine for coupling.  Coupling reagents can be very hygroscopic as well, so a little base doesn't hurt to get water away from them (if you use EDC, this is often sold as an HCl salt as well so base is necessary to deprotonate it).

[marthaj]

Thank you J-bone
But what I want to know is how I can remove the HOBt from the rex and the DMAP that I add to the rex.
I dont know in the end of the rex , those chemicals stay in the organic phase or in the aqueous phase.
Thank you again

[Doc Oc]

I often work up my peptide couplings with an acid and base wash (usually 1M HCl and 10% Na2CO3), and that's enough to get pretty pure product.

[elvirababe]

Whats the formula for sodium carbonate
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