OChem Extraction Question

[w4nt2baDDS]

Here is a picture of the question I am struggling with:

How come NaOH (a strong base) will deprotonate phenol but not other alcohols?

Is it because the resulting O- formed would be too unstable w/o resonance and therefore take a H from the resulting H2O that just formed?

If this is the case... then why would an alkyl(O-) be less stable than OH- ? The neighboring carbons inductively donate electrons which make alkyl-(O-) less stable than OH-?

I just want to make sure I'm thinking of this right, I always thought a strong base can rather easily deprotonate alcohols...

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[BYU4you]

Phenol is the strongest acid of those because like you said it's conjugate base is resonances stabilized.

 

[DAT Destroyer]

Here is a picture of the question I am struggling with:

View attachment 189613

How come NaOH (a strong base) will deprotonate phenol but not other alcohols?

Is it because the resulting O- formed would be too unstable w/o resonance and therefore take a H from the resulting H2O that just formed?

If this is the case... then why would an alkyl(O-) be less stable than OH- ? The neighboring carbons inductively donate electrons which make alkyl-(O-) less stable than OH-?

I just want to make sure I'm thinking of this right, I always thought a strong base can rather easily deprotonate alcohols...

The pka of phenol is 10.....the pka of alcohols is about 16........this means that phenols are more acidic.......by 1X10 *6 !!! Hence,,,,the phenol will be much more willing to give up a proton. NaOH would be more than adequate for the job. Alcohols are less willing to release the proton, and the equilibrium would be unfavorable . For alcohols, Sodium hydride NaH is a great base. This base will convert the alcohol into the alkoxide. Notice.....when the H is removed from phenol......we get a well-stabilized anion......this is due to the fact the negative charge can be shared among oxygens. The simple alcohol is unable to be stabilized,,,,,there is no resonance !!!

Hope this helps

Dr. Jim Romano

 

[w4nt2baDDS]

Thanks for the information guys.

I didn't realize phenol was nearly a million times more acidic than other alcohols!

I got thrown off because I figured the hydroxide could deprotonate both the phenol and the primary alcohol. Then, I incorrectly believed that the phenol would not be very soluble due to the nonpolar benzene ring and thus the deprotonated alcohol would be in the aqueous solution. Now I see why the alcohol wouldn't want to become deprotonated as much as the phenol and that phenol is plenty soluble once it has a negative charge to stabilize/react with sodium and the hydrogen parts of water.

This question seemed pretty rudimentary so I wanted to make sure I completely understood it.