Question

Shown below is the peak list of chemical shifts, multiplicities, numbers of protons (from integration), and coupling constants for the 1H NMR spectrum in Question 4.

a) Draw the chemical structure of trans-4-nitrochalcone. Circle the proton or protons that you would attempt to identify in the 1H NMR spectrum as evidence that the expected trans-isomer was formed (rather than the cis-isomer).

b) Identify the peak or peaks in the peak list that correspond(s) to the proton or protons circled in part (a). What specific information would verify the alkene stereochemical assignment?

H NMR spectrum peak shift, ppm (multiplicity, number of protons, coupling constant 8.27 (multiplet, 2 H 8.05 (multiplet, 2 H 7.81 (doublet, 1 H, J- 15.9 Hz) 7.79 (multiplet, 2 H 7.66 (doublet, 1 H, J 15.9 Hz) 7.63 (multiplet, 1 H 7.54 (multiplet, 2 H5.

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O2N trans-4-nitrochalcone O2N A H H NMR spectrum peak shift, ppm (multiplicity, number of protons, coupling constant 8.27 (mu

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