d. What evidence is there that the ortho and para isomers are present in small amounts in the product spectrum? Indicate what signals are being produced by which proton from which isomer, as completely as possible. Estimate the mole ratio of the ortho isomer to para isomer from the spectrum
In the NMR spectrum of the product, there are two sets of signals that correspond to the ortho and para isomers.
For the ortho isomer, we would expect to see signals from the aromatic protons that are adjacent to each other on the benzene ring. These protons would be in a coupling pattern known as an AB system, where the chemical shift difference between the two protons is relatively small. Therefore, we would expect to see two doublet peaks in the spectrum.
For the para isomer, we would expect to see signals from the aromatic protons that are across from each other on the benzene ring. These protons would not be directly coupled to each other, so we would expect to see two singlet peaks in the spectrum.
By analyzing the spectrum, we can estimate the mole ratio of the ortho isomer to para isomer based on the intensity of the peaks corresponding to each isomer. Typically, the peaks for the para isomer will be less intense than those for the ortho isomer due to the lower coupling constants. By comparing the integrated intensities of the peaks, we can estimate the relative amounts of each isomer in the product mixture.