Q13-17P - Organic Chemistry (Mcmurry)

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)

Step-by-Step Solution

Answer

The answer is,

(a) 4 

(b) 5

(c) 4

(d) 5

(e) 6

(f) 7

Step 1: 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.

Step 2: 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.

Step 3: 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.          

Step 4: 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.

Step 5: 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.

           

Step 6: 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.

Step 7: 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.