Which one is more downfield?

This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.
Status
Not open for further replies.

muhali3

Full Member
10+ Year Member
Joined
May 6, 2009
Messages
1,785
Reaction score
127
Is carbon 6 or carbon 4 more downfield/deshielded? I'm having a hard time seeing which one will be subject to a more electronegative pull, as they are both one carbon away from a nitrogen.
 

Attachments

  • molecule.jpg
    molecule.jpg
    10.2 KB · Views: 128
I know, it's an o-chem 2 extra credit problem. I don't know how to make sense of it. w/e
 
I didn't know that, I thought SDNers would want to give me an unfair advantage over all the other students in my class...shame on me for not thinking otherwise.
 
Four is more upfield (shielded) because the 2 nitrogens are closer to it than they are to 6. Hyperconjugation should play a minimal role compared to the inductive effect. IMHO
 
Consider it step by step.
Step 1: Both of the carbons are 1 carbon away from the Nitrogen. So you can't come up with an answer at this point.
Step 2: Both of the carbons away from #4 & #6 carbon are next to a Nitrogen. So you can't come up with an answer at this point either.

Now go further,
Step 3: The nitrogen closest to #6 carbon is attached to one CH3, whereas the nitrogen closest to #4 is attached to two CH3's (being more substituted).

Result: #4 is more deshielded (downfield) than #6.
 
Status
Not open for further replies.
Top