Why is phenol more polar than alcohol. I mean the benzene ring seems to be extremely unpolar. Furthermore, is the hydrogen bonding stronger in phenol than in alcohol? Are polarity and hydrogen bonding related (in hydroxy compounds)?

I am doing TLC and I was taught that hydrogen bonding can occur with the alcohol/phenol and that alcohol has stronger hydrogen bonding to the silica gel than it would have despite the lower polarity a lower Rf value than phenol.

But to be honest I am very unsure about those teachings.

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    $\begingroup$ When you say "phenol is more polar than alcohol", how are you quantifying polarity? Phenol has only moderate solubility in water, while ethanol and other small alcohols are infinitely miscible. Several small alcohols also have an appreciably higher dipole moment (~1.6 D) compared to phenol (1.2 D). $\endgroup$ – Nicolau Saker Neto Dec 2 '15 at 11:20

The OH group of phenol is indeed more polarized - and a stronger acid - than the OH group of an aliphatic alcohol - maybe that is what you are asking. There are two contributions to this:

(1) inductive: the sp2 hybridized carbon participating in the sigma bond to the OH group is more electron-withdrawing than the sp3-hybridized carbon of an alcohol bonded to OH; and

(2) mesomeric: the phenyl group allows non-bonding electrons on oxygen to partially delocalize into the ring via pi bonding.


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