Rank the labeled protons in order of increasing chemical shift.
The structure of an unknown compound is determined by spectral studies such as proton-NMR, carbon-13 NMR, IR spectra, and HRMS. In proton-NMR spectroscopy, the number of different protons that reside in the vicinity of the proton of interest can be determined by observing their corresponding NMR signals. Based on the number of the adjacent protons, the peaks of the required protons splits into a doublet (one proton), triplet (two protons), quartet (three protons), and so on. This observation is based on the rule, where n is an integer and I is the spin quantum number.
When the electron-withdrawing group is bonded to the carbon of the proton of interest, the peaks in the proton NMR spectra appear in the deshielded region (downfield). The electron-donating group increases the electron density on the C-H bond and the proton appears in the shielded region (upfield).
In the provided molecule, proton is next to the carbonyl group and hence it appears at .
The proton is also situated next to the carbonyl group, but it is bonded to another carbon atom, the high electronegativity of carbon as compared with hydrogen shifts the to the downfield region ().
The proton is bonded to the electronegative oxygen and it appears at the deshielded region .
The proton also resides near the oxygen. But the carbon of the C-H bond has only one adjacent carbon as compared to the two carbon in the C-H bond of proton. So, the value of appears slightly in the shielded region with .
The proton is situated between the two carbon atoms (away from the electron-withdrawing groups). So the proton appears in the shielded region with
Step by step
Solved in 3 steps
