2D NMR Experiments - HETCOR

2D NMR experiments can provide an abundance of information for the structural elucidation of chemical compounds. An older example of a 2D experiment is the heteronuclear correlation (HETCOR) sequence. In this experiment, two different nuclei (usually ¹³C and ¹H) are correlated through single bond spin-spin coupling, revealing which proton and carbon groups are bonded to each other. This experiment is similar to the HSQC (Heteronuclear Single Quantum Correlation) experiment; however, HETCOR is a less sensitive experiment since it is a carbon detected experiment, unlike HSQC which is a proton detected experiment. For more information about the HSQC experiment, please read our blog post “HSQC – Revealing the direct-bonded proton-carbon instrument”.

In Figure 1 the HETCOR spectrum of diethyl phthalate, obtained on the NMReady-60PRO, is depicted.

Figure 1.HETCOR spectrum of diethyl phthalate in CDCl3.

As you can see above, the HETCOR experiment shows signals in the contour plot with the chemical shifts of proton and carbons that are directly bonded. Let's go through the data and analyze it from high to low frequency.

The peaks at 167 ppm and 132 ppm are quaternary carbons and will not result in any correlations (this is expected since quaternary carbons don’t have protons directly attached (¹J_CH).

The peaks at 131 ppm and 129 ppm are the aromatic carbon signals which are bonded with the aromatic proton signals present at 7.5 ppm.

The peak at 60 ppm is directly bonded to the quartet (-CH₂) at 4.3 ppm.

The peak at 10 ppm is directly bonded to the triplet (-CH₃) at 1.2 ppm.

Please don’t hesitate to contact us if you have any questions about the HETCOR or HSQC experiment or if you want to see how our instrument can be incorporated into your workflow!