Question

How many unique 1H & 13C NMR signals exist in the spectrum of the following compounds?

How many unique 1H NMR signals exist in the spectrum of the following compounds? How many unique 13C NMR signals exist in the spectrum of the following compounds?

Answer 1

Concept and Reason

This problem is based on the concept of NMR spectroscopy.

NMR spectroscopy is a very good tool to analyze organic compounds. $^1{\rm{H}} - {\rm{NMR}}$ signal indicates number of ‘different sets’ of protons present in the molecule. $^{13}{\rm{C - NMR}}$ indicates number of ‘different sets’ of carbon atom present in the molecule.

Fundamentals

A set of protons with the same magnetic environment are called equivalent protons and give only one signal in the $^1{\rm{H}} - {\rm{NMR}}$ spectrum. Therefore, number of sets of protons reveal how many signals appear in the spectrum.

Similarly, a set of carbon atoms with the same magnetic environment are called equivalent carbons and give only one signal in the $^{13}{\rm{C - NMR}}$ spectrum. Therefore, number of sets of carbon atoms reveal how many signals appear in the spectrum.

(1.a)

The structure of the compound representing the value of chemical shift is as follows:

(1.b)

The structure of the compound representing the value of chemical shift is as follows:

(1.c)

The structure of the compound representing the value of chemical shift is as follows:

(1.d)

The structure of the compound representing the value of chemical shift is as follows:

(2.a)

The structure of the compound representing the value of chemical shift is as follows:

(2.b)

The structure of the compound representing the value of chemical shift is as follows:

(2.c)

The structure of the compound representing the value of chemical shift is as follows:

(2.d)

The structure of the compound representing the value of chemical shift is as follows:

(2.e)

The structure of the compound representing the value of chemical shift is as follows:

(2.f)

The structure of the compound representing the value of chemical shift is as follows:

Ans: Part 1.a

Number of $^1{\rm{H}} - {\rm{NMR}}$ signals is $3$ .

Part 1.b

Number of $^1{\rm{H}} - {\rm{NMR}}$ signals is $3$ .

Part 1.c

Number of $^1{\rm{H}} - {\rm{NMR}}$ signals is $5$ .

Part 1.d

Number of $^1{\rm{H}} - {\rm{NMR}}$ signals is $3$ .

Part 2.a

Number of $^{13}{\rm{C - NMR}}$ signals is $4$ .

Part 2.b

Number of $^{13}{\rm{C - NMR}}$ signals is $3$ .

Part 2.c

Number of $^{13}{\rm{C - NMR}}$ signals is $3$ .

Part 2.d

Number of $^{13}{\rm{C - NMR}}$ signals is $4$ .

Part 2.e

Number of $^{13}{\rm{C - NMR}}$ signals is $3$ .

Part 2.f

Number of $^{13}{\rm{C - NMR}}$ signals is $3$ .