separation of tautomer compounds

[dcobice]

Hi all,

I would like to know How can I try to separate in a C18 Column two tautomeric compounds, If you have any idea of How can i make this separations I mean ( mobile phase, aditives and something else)
Please contact me by e-mail and I really aprecciate your reply!!!

thanks In advance!

Diego

[Mark Tracy]

Whether it can be done at all depends on the rate of interconversion of the two tautomeric forms. Most such pairs are simply an intramolecular proton transfer that is rapid with respect to the chromatographic process; you will never succeed if that is the case.

[Srinivas SK]

Hello

There are two things to watch in tautomer separations:

1) pH. You will need to know the pH which the tautomerism occurs. For eg, keto-enol tautomerism is usually catalysed by acidic pH. Lower pH will favor the keto form ( as I recollect !). So, maintaining a pH that favors one tautomer would help.

2) Solvent polarity. Increasing solvent polarity would favor the keto form usually. So check out which solvent system is right for your sample.

If you're in luck, you will eventually wind up with two peaks, with acceptable resolution.

Hope this helps.

Rgds,

S.K. Srinivas

[JMB]

Dcobice,

Together with pH adjustment, you might also try dropping the column temperature, by immersion in an ice/water bath.

Please post your result---we could all learn from your problem.

JMB