My Rx resulted in the amide (final) having exact same Rf value as the start 1ry amine, I tried EA/Hex, MC/Me, & ether systems, any suggestion for separation?
Is your amide product neutral (and stable) at acidic pH? Could you add traces of acid to protonate the amine starting material and therefore increase its retention of silica?
Cheers,
Hi,
Amides are not really basic and are really hard to protonate due to the delocalisation of the N non-bonding electron pair with the carbonile. Good luck!
Hi, As per above suggestion you can add little acid in solvent system. Also try one more solvent system chloroform/methanol. I think it may change rf of your amine and amide. Also try to stain TLC after check in Uv chamber with iodine. Sometimes shade of spot different from one another in iodine. So distinguishable.
Compounds having same Rf value can be separated using silica treated with AgNO3( siver pregnated Silica).This is the case seen with a number of macrolide molecules.
An earlier suggestion about use of methanol/chroloform or methanol/Dichloromethane( 1-2% DCM component in methanol will be beneficial since compounds (eg triflates) have been known to be resolved using the same system.
Using the same mobile phase system solvent systen with Silica 230-400 in place of regular silica 60-120 will do help.
Prior to initiation of the experiments if you can arrange for a Refractive Index detector and subsequent analysis then you will get a quick idea about resolution of the compounds
As a side note, it is also possible that the reaction had failed. Have you been able to test if the end product is in solution?
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