phenol acidicity (orgo destoyer #154)

[Sea of ASH]

the question is that which one is the most acidic....

its obviously the one with a deactivating group.... the answer is p-nitrophenol... but why cant it be p-chlorophenol?

is there a scale of deactivating and/or activating group strengths?

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[achilles2]

the question is that which one is the most acidic....

its obviously the one with a deactivating group.... the answer is p-nitrophenol... but why cant it be p-chlorophenol?

is there a scale of deactivating and/or activating group strengths?

yes this is a common mistake, an even harder question would be which is more acidic p-nitrophenol or m-nitrophenol (the p is) para and ortho groups have more of an effect them meta remember that.

Now a nitro group is VERY electron withdrawing more so then halides.

In terms of halides F is more electronegative so it makes the compound more acidic then say CL

Also the more electron withdrawing groups you have on the stronger the acid so like 2,4 dinitro phenol is more acidic then nitrophenol which is more acidic then o-flurophenol which is more acidic then m-flurophenol which is more acidic then m-chlorophenol


Generally if you see NO2 group (on a ring) that compound is going to be the most acidic.

Hope this helps a bit