December 28, 2024, 04:24:30 AM
Forum Rules: Read This Before Posting


Topic: nucleophilic attack  (Read 2963 times)

0 Members and 3 Guests are viewing this topic.

Offline helper

  • Regular Member
  • ***
  • Posts: 69
  • Mole Snacks: +3/-1
nucleophilic attack
« on: July 14, 2013, 07:28:43 AM »
hello,


thanks

Offline Dan

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 4716
  • Mole Snacks: +469/-72
  • Gender: Male
  • Organic Chemist
    • My research
Re: nucleophilic attack
« Reply #1 on: July 14, 2013, 08:53:29 AM »
Your logic is good. The Meisenheimer complex arising from attack at the para position has a negative charge conjugated with the nitro group. Attack at the meta position give a carbanion that is not conjugated with the nitro group (and is therefore less stable).

Be careful with your generalisation, what do you think you would get if this was the starting material:

c1([N+]([O-])=O)c(Cl)c(Cl)ccc1
My research: Google Scholar and Researchgate

Offline helper

  • Regular Member
  • ***
  • Posts: 69
  • Mole Snacks: +3/-1
Re: nucleophilic attack
« Reply #2 on: July 14, 2013, 10:31:24 AM »
thanks,

the attack would be on the meta cl  to the nitro.

so we have to exmaine each case on its merits!

Offline orgopete

  • Chemist
  • Sr. Member
  • *
  • Posts: 2636
  • Mole Snacks: +213/-71
    • Curved Arrow Press
Re: nucleophilic attack
« Reply #3 on: July 14, 2013, 12:08:53 PM »
Please draw the Meisenheimer intermediate(s).
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

Offline Dan

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 4716
  • Mole Snacks: +469/-72
  • Gender: Male
  • Organic Chemist
    • My research
Re: nucleophilic attack
« Reply #4 on: July 15, 2013, 05:31:40 AM »
the attack would be on the meta cl  to the nitro.

Why?
My research: Google Scholar and Researchgate

Offline orgopete

  • Chemist
  • Sr. Member
  • *
  • Posts: 2636
  • Mole Snacks: +213/-71
    • Curved Arrow Press
Re: nucleophilic attack
« Reply #5 on: July 15, 2013, 10:40:30 AM »
the attack would be on the meta cl  to the nitro.

Why?

Although the answer was explained by Dan, it is my opinion the poster has simply not drawn the Meisenheimer intermediates that confirm Dan's explanation. I am guessing because the question was being asked, the poster is either unwilling or unable to draw them. I am aware that some professors place little emphasis on mechanisms and thus students avoid writing them. I suspect this is such a case. Had the poster simply drawn the complexes, I believe the poster would have discovered the answer for him or herself.
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

Offline antimatter101

  • Full Member
  • ****
  • Posts: 163
  • Mole Snacks: +9/-26
Re: nucleophilic attack
« Reply #6 on: July 17, 2013, 07:00:07 AM »
Search up:

Nucleophilic substitution,

Ortho-para deactivators,

Ortho-para activators,

and Meta deactivators.

Sponsored Links