LSC: mobile phase cyclohexane/ethylacetate

[chantal]

problem: I´ve got a mixture of two substances in order to seperate them: the compounds are 3-nitroacetanilide and 1,3,5-trihydroxybenzene. My stationary phase was silica gel (normal phase) and my solvent liquid phase was a 1:1 mixture of cyclohexane and ethylacatete. The two compounds could be seperated, but I don`t know which one came out first. I identified the two compounds via IR spectroscopy at the end of my experiment, but the thing is I can`t remember which crystal was the first fraction. I think I swapped them, I have no idea. And unfortunately, I chucked them, so there is no chance to do a TL and check which one goes faster than the other. So, my question is:
Can someone tell me, which compound goes faster than the other and is the first fraction??

[chantal]

isn´t that the less polar compound which comes out first??

[danko]

Yes!

Best Regards

[chantal]

thank you... and which one is it? is it the 1,3,5-trihydroxybenzene? Is that right? i mean, the 3-nitroacetanilide isn`t really that polar, or is it in this liquid phase of 1:1 cyclohexane and ethylacetate...

[danko]

I would suspect 3-nitroacetanilide to be the less polar. But under all circumstances, I think you’ll need to re-test in order for you to be completely sure of what is what.

Best Regards

[HW Mueller]

Take-home exam? The trihydroxybenzene is symmetrical, shouldn´t have much of a dipole moment. But one should not forget the hydrogen bonding possible here. So Danko´s sequence is probably correct. Also, this shows how difficult such predictions are, I agree: if this is a real problem then there is no way around getting the standards again.