DreamingOfDentistry

Full Member
5+ Year Member
May 20, 2014
130
80
Status (Visible)
  1. Pre-Dental
  2. Dental Student
Would adding a deactivating or activating group speed up this reaction!? I know its not an EAS reaction and cant think "oh a donating group would cause it to react faster." I've also read a paper that said esters react similarly like amides and go quicker with electron withdrawing groups. Does anyone know for sure?
Thanks,
 

orgoman22

DAT DESTROYER
Sponsor
Vendor
15+ Year Member
Mar 12, 2005
4,548
3,342
New York City
www.orgoman.com
Status (Visible)
  1. Non-Student
Would adding a deactivating or activating group speed up this reaction!? I know its not an EAS reaction and cant think "oh a donating group would cause it to react faster." I've also read a paper that said esters react similarly like amides and go quicker with electron withdrawing groups. Does anyone know for sure?
Thanks,

An ester would indeed react faster in ACYL SUBSTITUTION reactions which are characteristic of the family of compounds. The electron withdrawing group such as CF3 would make the ester have a greater electrophilicity when reaction with a nucleophile. If you want a few examples of this, the Francis Carey book would be appropriate.

Hope this helps.
 

DreamingOfDentistry

Full Member
5+ Year Member
May 20, 2014
130
80
Status (Visible)
  1. Pre-Dental
  2. Dental Student
Well what about hydrolysis reactions though? Its an ester on a benzene ring. The options had some activating and deactivating groups like NH2, NO2, and other groups. You're breaking down the ester, not substituting it onto an aryl group right? That isn't the same sort of reaction as acyl substitution so wouldn't it work differently? I've got the basics down for EAS activating/deactivating but this question through me for a loop. I fear I'm over complicating this though...
 

tommyngu

Full Member
10+ Year Member
May 29, 2010
71
14
Southern California
Status (Visible)
  1. Pre-Dental
I don't quite understand the question. Are you asking if adding an activating or deactivating group to a benzene ring that has an ester on it will increase or decrease the rate of reaction for the hydrolysis of the ester? The term activating/deactivating usually refers to groups that are already on the ring, but I'll assume you mean electron donating/withdrawing groups. So going with this, I would think it would depend on which position of the benzene ring this EDG/EWG would be on. If the group removes electron density from the carbonyl carbon of the ester, then it should increase the reaction rate of the hydrolysis of the ester.
 
About the Ads

DreamingOfDentistry

Full Member
5+ Year Member
May 20, 2014
130
80
Status (Visible)
  1. Pre-Dental
  2. Dental Student
I don't quite understand the question. Are you asking if adding an activating or deactivating group to a benzene ring that has an ester on it will increase or decrease the rate of reaction for the hydrolysis of the ester? The term activating/deactivating usually refers to groups that are already on the ring, but I'll assume you mean electron donating/withdrawing groups. So going with this, I would think it would depend on which position of the benzene ring this EDG/EWG would be on. If the group removes electron density from the carbonyl carbon of the ester, then it should increase the reaction rate of the hydrolysis of the ester.
I think you answered my question! Haha sorry for the confusing question. The question in my book had an Ester with different substitute fs and asked which would undergo hydrolysis faster. Does it go faster because electrons withdrawing groups make the ester a better electrophile and thus more likely to become hydrolysed?
 

tommyngu

Full Member
10+ Year Member
May 29, 2010
71
14
Southern California
Status (Visible)
  1. Pre-Dental
That's what I would think since during hydrolysis the nucleophile would react with the electrophilic carbonyl carbon. Electron withdrawing groups attached to the carbonyl carbon (or near it) would make that carbon more electrophilic and therefore more favorable to be attacked by the nucleophile. This should result in a lower transition state which means a faster reaction rate. You have to be careful about explaining it in terms of kinetics vs thermodynamics. I still might be confusing the two here... Having an EWG might make the reaction more likely to occur, but it might not necessarily make it occur faster. But in this case, I do believe that the EWG would also increase the rate. You might wanna look into it more.
 

DreamingOfDentistry

Full Member
5+ Year Member
May 20, 2014
130
80
Status (Visible)
  1. Pre-Dental
  2. Dental Student
hahah I did! I read some scientific paper I found online saying they reacted similar to amides or amines (cant remember which) and react faster with electron withdrawing groups. Just wanted to double check and see if theres anybody who could verify or explain it better.
 
This thread is more than 5 years old.

Your message may be considered spam for the following reasons:

  1. Your new thread title is very short, and likely is unhelpful.
  2. Your reply is very short and likely does not add anything to the thread.
  3. Your reply is very long and likely does not add anything to the thread.
  4. It is very likely that it does not need any further discussion and thus bumping it serves no purpose.
  5. Your message is mostly quotes or spoilers.
  6. Your reply has occurred very quickly after a previous reply and likely does not add anything to the thread.
  7. This thread is locked.