Question

The 1 H NMR data for methyl E-4-methoxycinnamate in deuterated chloroform (CDCl3) is as follows: δ (ppm) 7.64 (d, J=15.9 Hz), 7.48 (d, J = 8.7 Hz), 6.92 (d, J=8.7 Hz), 6.33 (d, J=15.9 Hz), 3.83 (s, 3H) and 3.79 (s, 3H). Consider the symmetry, mutual splitting pattern of the hydrogens and chemical shifts and assign the peaks in the 1 H NMR spectrum to the hydrogens in E-4-methoxycinnamate. Briefly explain your assignment and justify the E geometry of the double bond.

Answer 1