Phenol Acidity ?

[busupshot83]

Is the following true?

Halogens are deactivating, but direct ortho/para.
Deactivating groups increase phenol acidity.
Therefore, halogens will increase phenol acidity.

If so, do nitro groups cause a greater increase in phenol acidity than halogens?

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[poc91nc]

Is the following true?

Halogens are deactivating, but direct ortho/para.
Deactivating groups increase phenol acidity.
Therefore, halogens will increase phenol acidity.

If so, do nitro groups cause a greater increase in phenol acidity than halogens?

Yup halogens are deactivating and direct ORTHO PARA...same goes for -NO

Deactivating groups will increase acidity..especially at ortho-para. para-nitrophenol more acidic than meta-nitrophenol

Halogens will increase acidity...but not as good as nitro.

 

[busupshot83]

Yup halogens are deactivating and direct meta...same goes for -NO

Deactivating groups will increase acidity..especially at ortho-para. para-nitrophenol more acidic than meta-nitrophenol

Halogens will increase acidity...but not as good as nitro.

Awesome, thanks Poc.

 

[poc91nc]

I mean halogens direct ortho para but are deactivating same with -NO

 

[busupshot83]

I mean halogens direct ortho para but are deactivating same with -NO

K, I was just about to ask you about that.

 

[poc91nc]

There is one other not commonly asked deactivator that is ortho/para directing...in addition to halogens and -NO...but I can't think of it...just something to keep in mind.

 

[busupshot83]

There is one other not commonly asked deactivator that is ortho/para directing...in addition to halogens and -NO...but I can't think of it...just something to keep in mind.

Yeah, good looking out: NO is one of them. I can't think of the other neither. Thanks again, you have been a huge help. I'm going to study again, pce.

 

[DailyDrivenTJ]

Phenol's acidity is increased when EWG is present on the ring. This is because once the proton/hydrogen from the oxygen is removed, the conjugate base is stablized by the electron withdrawing group on the ring such as halogen. This is what makes the phenol acidic. EWG on O/P position will yield more acidic product via resonance stablization compared EWG on the meta position via induction.

 

[lor]

in aromatic molecules,
the acidity increase by adding an electron with-drawing group to the ring. it could be NO2 or Br etc.
the basisity of the ring on the other hand increase with the electron donating groups such as NH2
what if you have to groups attached to the aromatic ring, let's say NO2 and NH2 and you are asked to add another one to the ring...make sure you go by the configuration of electron donating/activating group in this case NH2. so you need to think ortho and para in this case
KNOW pages 321, 324 and 326 of the Kaplan blue book as well, you don't regret it
best of luck

 

[theedaddy77]

no2 is electron withdrawing and M derecting..... not ortho para. While halogens are elctron withdrawing but are Ortho para due to increase resonance.

 

[ucla2134]

Phenol's acidity is increased when EWG is present on the ring. This is because once the proton/hydrogen from the oxygen is removed, the conjugate base is stablized by the electron withdrawing group on the ring such as halogen. This is what makes the phenol acidic. EWG on O/P position will yield more acidic product via resonance stablization compared EWG on the meta position via induction.

What is EWG?
Thanks

 

[TeamGuo]

What is EWG?
Thanks

electron withdrawing. Ex. NO2

 

[ddsjc2014]

no2 is electron withdrawing and M derecting..... not ortho para. While halogens are elctron withdrawing but are Ortho para due to increase resonance.

yep...NO2 is M directing, EWG. increase acidity than halogens.

 

[ucla2134]

yep...NO2 is M directing, EWG. increase acidity than halogens.

If NO2 is M directing EWG, the why in the kaplan book says that methyl group directs substitution products for M is only for 3%, but ortho and para it is 63% and 34% respectively??
Anyone know this?
Thanks