a.[2]
Explain the use of tetramethylsilane (TMS) and deuterated solvents such as CDCl3\text{CDCl}_3CDCl3 in proton (1H^1\text{H}1H) NMR spectroscopy.
b.[6]
An organic compound J is analysed using a combination of analytical techniques. The data obtained is shown below:
- Elemental analysis by mass: C: 56.69%, H: 7.09%, N: 11.02%, O: 25.20%
- Mass spectrum: Molecular ion peak at m/z=127.0m/z = 127.0m/z=127.0
- IR spectrum: Absorptions at 2250 cm−12250\text{ cm}^{-1}2250 cm−1 and 1745 cm−11745\text{ cm}^{-1}1745 cm−1
- Proton NMR spectrum data:
- δ=3.8 ppm\delta = 3.8\text{ ppm}δ=3.8 ppm, singlet, integration = 3H3\text{H}3H
- δ=3.5 ppm\delta = 3.5\text{ ppm}δ=3.5 ppm, triplet, integration = 1H1\text{H}1H
- δ=2.0 ppm\delta = 2.0\text{ ppm}δ=2.0 ppm, multiplet (quintet), integration = 2H2\text{H}2H
- δ=1.1 ppm\delta = 1.1\text{ ppm}δ=1.1 ppm, triplet, integration = 3H3\text{H}3H
Determine the structure of compound J. Show all your reasoning.
