Polarity question

[ImmunoRocks]

Hello!

There was this question on AAMC 7 about the Rf value of this ketone cyclic-ring vs just a hydroxyl group on the cyclic-ring. Which one is more polar? And if it's more polar, then it probably doesn't travel up the TLC as far? Is this right?

Thanks

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[akalin24]

Correct! Anytime you compare the polarity of two different molecules.... the molecule that can act as both a H-bond donor and acceptor has the higher dipole moment. TLC usually has a polar (adsorbant) stationary phase so the molecule with the greatest polarity will have the smallest Rf value.

Good Luck tomorrow!

AK

 

[Cerberus]

Hello!

There was this question on AAMC 7 about the Rf value of this ketone cyclic-ring vs just a hydroxyl group on the cyclic-ring. Which one is more polar? And if it's more polar, then it probably doesn't travel up the TLC as far? Is this right?

Thanks

The hydroxyl is more polar than the =O, this means it has a smaller Rf value (so yeah, it travels less).