December 24, 2024, 09:06:28 PM
Forum Rules: Read This Before Posting


Topic: NMR of an Aldol help please  (Read 3448 times)

0 Members and 1 Guest are viewing this topic.

Offline rachelrayne

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-0
NMR of an Aldol help please
« on: April 28, 2008, 09:16:14 PM »
Hey, I'm trying to determine the structure of an aldol that I synthesized from an unknown aldehyde and ketone. I think that my unknowns are 3,5-dibromosalicylaldehyde and 2-nonanone and based on the NMR I was given I think that may be correct. But I'm not that great at NMR so I was wondering if someone could let me know what they thought.
I wasn't given a formula, but the signals I got were:
8.8 doublet 2H
8.4 doublet 2H
6.9 singlet 1H
2.1 singlet 3H
1.9 triplet 2H
1.0 multiplet 8H
0.5 triplet 3H

Thank you very much

Offline sjb

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 3653
  • Mole Snacks: +222/-42
  • Gender: Male
Re: NMR of an Aldol help please
« Reply #1 on: April 29, 2008, 03:18:59 AM »
Simply from the NMR shifts and the multiplicities, it may be very hard to distinguish between, for instance 3,5-dibromosalicylaldehyde or 3,5-dichlorosalicylaldehyde.

Do you have the J values as well? What solvent did you run the NMR in?

S

Offline sjb

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 3653
  • Mole Snacks: +222/-42
  • Gender: Male
Re: NMR of an Aldol help please
« Reply #2 on: April 29, 2008, 09:49:05 AM »
Another point is that your peaks in the aromatic region do not correlate to your desired molecule.

How many aromatic protons can you see with your compound, and how many in the NMR?

Without a list of possible ketones and aldehydes this question could have several answers - do you have such a list?

Sponsored Links