Question

Please write neatly.

6. Below are seven spectra: 2 x 11-NMR. 3 x 1·1x C-NMR, and 1 x MS, m hat order. At the bottom of the page there are seven structures, Match each structure with a spectrum by writing the letter for the structure in the box on the correct spectrum. Fach structure and spectrum should be used only once HC-CH2-C CH3 OH 6 NH2 CH

Answer 1

First, let us assign a molecule to 1 ¹³C-NMR given. In the ¹³C-NMR given, we can observe that there are only two peaks(¹³C-NMR is the one where ppm values range from 0-200 on the x-axis). The observance of just two peaks in the NMR means that there are only two chemically and magnetically different carbons present in the molecule. The only such molecules with 2 carbons from the choices provided is 5. Thus, 5 corresponds to ¹³C-NMR.

¹H-NMR is the one where ppm values range from 0-10 ppm on the x-axis. We are given two ¹H-NMR here. In one of the ¹H-NMR, we can observe a peak(singlet) around 10 ppm which is the signature peak for an aldehyde proton. From the given choices, 4 is an aldehyde molecule. Thus, 4 belongs to ¹H-NMR with a peak at 10 ppm. In the second ¹H-NMR, we can observe a singlet, triplet, and quartet. Also, we do not observe any peaks around 7-8 ppm which correspond to aromatic proton peaks. This means that the molecule is not aromatic, as a result of which we are left with 3 and 6. Now, triplet and quartet peaks are not possible in molecule 3 as there is no coupling possible. Thus, 6 belongs to the other ¹H-NMR.

From the mass spectrum, we can observe that the M⁺ peak is around 100 - 110 units. This means that the molar mass of the molecule is in this range. The only molecule to have its molar mass in the above range is molecule 3. Thus, 3(Molar mass = 102 units) corresponds to mass-spectrum.

From the IR spectrum, all three have peaks around 1700 cm^-1 corresponding to C=O stretches in the respective molecules. Now, O-H stretch can be observed at 3600 cm^-1, the peak is broad. Thus, 2 belongs to the IR spectrum with a broad peak at 3600 cm^-1. Amide signature stretching peaks are observed around 3100 - 3500 cm^-1, 2 peaks are observed in this region. Molecule 7 is an amide. 7 corresponds to the IR spectrum with two peaks observed around 3100 - 3500 cm^-1. The last molecule that is 1 corresponds to the IR spectrum with a peak at 1700 cm^-1 and a peak at 500-600 cm^-1corresponding to C-Br stretch.