Question

Question: Predict the number of carbon resonance lines you would expect in the C- 13 NMR spectra of the following compounds:

(a) Methylcyclopentane

(b) 1- Methylcyclohexane

(c) 1,2- Dimethylbenzene

(d) 2- Methyl-2-butene

(e)

(f)

Short answer

The answer is,

(a) 4

(b) 5

(c) 4

(d) 5

(e) 6

(f) 7

Step-by-step solution

C-13 NMR

The C-13 NMR spectroscopy is the spectroscopic technique in which the spectral lines corresponding to the number of carbon depending on the atmosphere of the carbon atoms and splitting takes place.

Subpart (a)

The structure of methylcyclopentane is shown below

Structure
The structure of the given compound shows that the compound is symmetrical by a 4 carbon moiety. This shows that there are four carbon atoms which are not identical. Hence the number of resonance lines in the compound is 4.

Subpart (b)

The structure of 1-methylcyclohexane is shown below.

Structure

The structure of the given compound shows that the compound is symmetrical by a 5 carbon moiety. This shows that there are five carbon atoms which are not identical. Hence the number of resonance lines in the compound is 5.

Subpart (c)

The structure of 1,2- Dimethylbenzene is shown below.

Structure
The structure of the given compound shows that the compound is symmetrical by a 4 carbon moiety. This shows that there are four carbon atoms which are not identical. Hence the number of resonance lines in the compound is 4.

Subpart (d)

The structure of 2- methyl- 2- butane is shown below.

Structure
The structure of the given compound shows that the compound is symmetrical by a 5 carbon moiety. This shows that there are five carbon atoms which are not identical. Hence the number of resonance lines in the compound is 5.

Subpart (e)

The given compound is shown below.The given compound is shown below.

Structure

The structure of the given compound shows that the compound is symmetrical by a 6 carbon moiety. This shows that there are six carbon atoms which are not identical. Hence the number of resonance lines in the compound is 6.

Subpart (f)

The given compound is shown below.

Structure

The structure of the given compound shows that the compound is symmetrical by a 7 carbon moiety. This shows that there are seven carbon atoms which are not identical. Hence the number of resonance lines in the compound is 7.