Topic: Substitution at one amine but not the other.. why? (Read 2535 times)

Annna · « **on:** August 16, 2015, 04:58:11 AM »

Can someone please help me explain why this nucleophilic substitution happens at only one of the two amines

Dan · « **Reply #1 on:** August 16, 2015, 08:53:59 AM »

Think about resonance structures and consider the partial charges on each N.

Annna · « **Reply #2 on:** August 16, 2015, 10:17:21 PM »

This is the only solution I can come up with, but does this makes sense to why there should be a neg. partiel charge on N?

Dan · « **Reply #3 on:** August 17, 2015, 02:30:58 AM »

Think about the conjugation of the exocyclic N lone pairs - one of them is conjugated to an electron withdrawing group.

Annna · « **Reply #4 on:** August 17, 2015, 03:53:05 AM »

Hope this is what you meant, because this makes sense to why its more nucleophilic than the other one!

Dan · « **Reply #5 on:** August 17, 2015, 04:14:31 AM »

Hope this is what you meant

Yes - this is how I would rationalize the observed selectivity.