orgo

This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.

recyrb

Full Member
Joined
Dec 28, 2010
Messages
127
Reaction score
0

Members don't see this ad.
which is a stronger conjugate base of phenol

a donating group in the ortho position, meta position or para position and why? thanks
 
Last edited:

Impulse155

Full Member
5+ Year Member
Joined
Nov 21, 2009
Messages
622
Reaction score
12
Im pretty sure meta position is the most basic.
Ortho and para are the most acidic due to the fact that if you put the + on the ortho and para you can stabilize it by doing resonance where if you put it on the meta it will get skipped over when you do your resonance.
However stronger acids have weak conjugate bases. Therefore I would assume that it would be meta which would be the strongest base since its the least acidic.

Im like 75% sure this is right.
 

yappy

Full Member
10+ Year Member
Joined
Jul 11, 2008
Messages
3,567
Reaction score
1,154
Phenols conjugate base is the phenoxide ion. It has four resonance structures. When drawing the resonance structures you'll notice that the negative charge moves from the oxygen to the ortho to the para then to the next ortho position.

Therefore, we observe that the ortho and para position of the phenoxide ion has the most negaitive charactor in these positions.

Now we can answer your question. Attaching a group - wheather it be electron donating or electron withdrawing - to the ortho/para positions will influence the acidity of phenol the most. This is because electron withdrawing groups will stabilize the phenoxide ion's more negative regions best if attached to those sites (spreading out the negative charge if you will). Conversely, electron donating groups will destabilize the phenoxide ion (amplifying the negative charactor).

This leads to the answer - electron donating groups destabilize the phenoxide ion, making it a stronger conjugate base. A stronger conjugate base leads to weaker phenol acidity.
 
Last edited:

Similar threads

Top