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Number of signals in a ¹H NMR spectrum can be calculating by counting its non-equivalent protons.

Types of protons in 1,2-dinitrobenzene

There are 2 non-equivalent ‘a’, ‘b’ protons present in the compound. These protons give 2 signals in ¹H NMR of 1,2-dinitrobenzene.

Types of protons in 1,3-dinitrobenzene

The structure shows 3 non-equivalent protons labelled as ‘a’, ‘b’, ‘c’. Thus, 3 signals are observed in the ¹H NMR spectra of 1,3-dinitrobenzene.

c) 1, 4-dinitrobenzene

Types of protons in 1,4-dinitrobenzene

All the protons present are equivalent as labelled ‘a’ in the structure. Thus, this compound contributes 1 signalin ¹H NMR spectra.

Thus, these compounds can be differentiated in ¹H NMR spectra using the number of signals observed for each compound.

Number of signals in a ¹³C NMR spectrum can be calculated by counting its non-equivalent carbons.

a) 1,2-dinitrobenzene

Non-equivalent carbons

There are 3 non-equivalent carbons labelled as ‘a’, ‘b’, ‘c’. Thus,¹³C NMR spectra of this compound gives three signals.

b) 1, 3-dinitrobenzene

Non-equivalent carbons

There are 4 non-equivalent carbons labelled as ‘a’, ‘b’, ‘c’, ‘d’. Thus, ¹³C NMR spectra of this compound gives 4 signals.

c) 1, 4-dinitrobenzene

Non-equivalent carbons

There are 2 non-equivalent carbons labelled as ‘a’, ‘b’. Thus, ¹³C NMR spectra of this compound gives 2 signals.