The last remaining peak at 4.999 ppm must be proton 13; this is confirmed by COSY correlation with proton 12, triplet multiplicity based on splitting by proton 12, and integration of one proton.

Nmr Of Cu(Dmg)2 Full Structural Characterization

When submitting to the FDA or other regulatory agencies, full structural characterization by NMR provides crucial evidence of compound identity.

A combination of 1-dimensional and 2-dimensional NMR experiments are necessary for complete confidence in chemical structure.

Nmr Of Cu(Dmg)2 How To Perform NMR

This post will walk you through the steps to fully characterize a molecule by 1- and 2-dimensional NMR, including on how to perform NMR interpretation.

In this example, only three protons can be assigned by the proton spectrum alone: protons 3, 4, and 6.

Proton 3 is the only methyl group in the structure, and therefore must integrate to 3 protons.

The only peak with an integration of 3 is the doublet at 1.770 ppm.

The peak is split into a doublet with a coupling constant of 1.2 Hz, reflecting the long-range coupling between protons 3 and 4, which also supports this assignment.

The long-range coupling constant observed for proton 3 (J1.2 Hz, split into a doublet by proton 4) is reflected in the coupling constant for proton 4 (J1.2 Hz, split into a quartet by proton 3).

Therefore, the peak at 7.690 ppm must represent proton 4 The integration and chemical shift support the assignment, as proton 4 is the only aromatic proton in the structure.

The only proton that should show up as a singlet is proton 6, as it has no neighboring protons that would split the peak (the nearest proton is 5 bonds away).

The chemical shift of 11.256 ppm supports this assignment, as imide protons often show up far downfield.

The peak also integrates to 1 proton, supporting the assignment.

While 2-bond and 3-bond H-H coupling is easily visible by COSY, long range coupling can also be observed with long acquisition times.

The cross-peaks (not on the diagonal) that are symmetric to the diagonal show the COSY correlations.

For example, protons 3 and 4 are coupled to each other, since they form a box pattern symmetric to the diagonal.

This confirms assignments 3 and 4 made from the proton spectrum alone.

Look at the table for any clear differences in correlation and begin there In this example, all unassigned protons show one or two COSY correlations-except the proton at 4.233 ppm, which correlates to three other protons by COSY.

The only proton expected to correlate with three nonequivalent protons is proton 9.

Thymidines structure suggests that proton 9 should couple protons 8, 10, and 11.

Based on the COSY, proton 9 couples protons at 2.068 ppm (2H), 3.754 ppm (1H), and 5.209 ppm (1H).

From this list, we can easily assign proton 8 as the peak at 2.068 ppm based on its integration of 2 protons.

To differentiate protons 10 and 11, take a look at our COSY table; 3.754 ppm shows two COSY correlations, while 5.209 ppm only shows one.

Therefore, we can assign proton 10 as 5.209 ppm and proton 11 as 3.754 ppm.

Proton 7s peak at 6.163 ppm is split into a triplet by the two 8 protons, confirming the assignment.

We can assign proton 12 (3.564 ppm) based on its integration of 2H and its COSY correlation to proton 11.