13C NMR.
Draw the structure of methyl m-nitrobenzoate
Determine the # of unique Carbons with approximate chemical shift (I = 0-50, II = 50-100, III = 100-150, IV >150 ppm) and expected multiplicity (splitting pattern)
To determine the number of unique carbons and their expected chemical shifts and multiplicities in the 13C NMR spectrum of methyl m-nitrobenzoate, we first need to draw its structure.
The structure of methyl m-nitrobenzoate is as follows:
CH3-C6H4-NO2
Now, let's analyze the carbon atoms in this molecule:
1. The methyl (CH3) group attached to the benzene ring will show a peak in region I (0-50 ppm) with a singlet pattern due to the presence of 3 equivalent carbons.
2. The carbon atoms in the benzene ring will also appear in region I (0-50 ppm) with a peak for each carbon. The carbon atoms in the benzene ring will show a peak in region I (0-50 ppm) with a peak for each carbon. These are typically observed as a single peak in the NMR spectrum due to the high symmetry of the benzene ring.
3. The nitro group (NO2) will show a peak in region III (>100 ppm) due to the deshielding effect caused by the electronegative nitrogen and oxygen atoms. The nitro carbon is expected to be observed as a singlet due to its isolation from other carbon atoms.
In summary, the 13C NMR spectrum of methyl m-nitrobenzoate is expected to show:
- 3 unique carbon signals
- Chemical shift ranges:
I (0-50 ppm) - 4 carbons (3 from benzene ring, 1 from methyl group)
III (>100 ppm) - 1 carbon (nitro group)
- Multiplicity:
I (0-50 ppm) - Singlet
III (>100 ppm) - Singlet