1H-NMR for conformation elucidation

  • Thread starter Thread starter amattiol
  • Start date Start date
Click For Summary
SUMMARY

The discussion centers on the challenges of determining the conformer and assigning H-NMR peaks for N,N-diisopropylacetamidine in CD3CN. Key peaks identified include a singlet at 5.8 ppm for R-NH, a septet at 4.00 ppm for the CH connected to the nitrogen, and multiple singlets at 2.37 ppm and 2.15 ppm. The participant suspects the E conformation based on theoretical considerations and steric repulsions but lacks sufficient NMR data to confirm this. They propose the possibility of both E and unfavorable Z conformations existing in solution.

PREREQUISITES
  • Understanding of 1H-NMR spectroscopy
  • Knowledge of conformational analysis in organic chemistry
  • Familiarity with N,N-diisopropylacetamidine structure and properties
  • Experience with solvent effects in NMR, specifically CD3CN
NEXT STEPS
  • Research advanced techniques for 1H-NMR peak assignment
  • Explore conformational analysis methods for amines
  • Learn about solvent effects on NMR spectra, focusing on CD3CN
  • Investigate variable temperature NMR techniques for conformational studies
USEFUL FOR

Chemists, particularly organic chemists and researchers involved in NMR spectroscopy, will benefit from this discussion as it addresses practical challenges in conformational analysis and peak assignment.

amattiol
Messages
7
Reaction score
0
Hello,
I have having some difficulty determining the conformer and assigning H-NMR peaks for a compound with a N,N-diisopropylacetamidine (R-NH-C(CH3)N(2[CH[2(CH3)]])... essentially a diisopropylamine added to CH3CN (ACN). my H-NMR spectrum (at room temp) in CD3CN consists of:
I have assigned all but the singlets

B singlet at 5.8ppm R-NH
B septet at 4.00 CH connected to the N of the diisopropylamine
singlet 2.37
singlet 2.15
TMS at 1.98
doublet at 1.26ppm methyls from the isopropyl
Very B singlet -4.9 μ-BHB

The E conformation is suspected based on theory and steric repulsions, but i cannot justify it from any of the NMR data I have (1H, variable temp 13C, or 11B)

my best guess in regards to those singles is that both E and unfavorable Z conformations exist in solution.

Any help would be greatly appreciated.
 
Chemistry news on Phys.org
I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?