Skip To Content

Identifying Peak Overlap on an HMBC Spectrum … Part 2

May 4, 2009
by Arvin Moser, Team Manager, Application Scientists, ACD/Labs

One of the trickiest parts of interpreting a 1H-13C HMBC is deciding whether a 13C resonance is coinciding with another 13C resonance, i.e. overlapping 13C peaks. A past blog, Part 1, describes a specific case where the possibility of two coinciding 13C resonances can be deciphered based on a high carbon correlation count. Herein, we present a specific case for a 1H-13C HMBC with paired 1J responses to distinguish peak overlap.

The 1H -13C HMBC spectrum below illustrates 2 protons multiplets at 1.89 and 2.37 ppm and 2 carbon resonances at 26.8 and 43.0 ppm. The paired 1J responses at 43.0 ppm indicate a CH2 group with the proton multiplet at 1.89 ppm. Similarly, the carbon at 26.8 ppm shows a paired 1J response with the proton multiplet at 2.37 ppm (CH group). In addition, a single correlation at exactly 2.37, 26.8 ppm indicates a quaternary carbon coinciding with the carbon resonance for the CH group.

HMBC1JOverlap_Spec_May42009

The quaternary carbon and CH group are in the vicinity of each other.

HMBC1JOverlap_Str_May42009

Join our newsletter!

Keep up-to-date with our quarterly newsletter that brings you the latest educational webinars, resources, tips, and tricks.

This field is for validation purposes and should be left unchanged.

Comments

Your email address will not be published. Required fields are marked *

Join our newsletter!

Keep up-to-date with our quarterly newsletter that brings you the latest educational webinars, resources, tips, and tricks.

This field is for validation purposes and should be left unchanged.