Question

How many unique 13C NMR signals exist in the spectrum for the following compound?

How many unique 13C NMR signals exist in the spectrum for the following compound?

Answer 1

Concepts and reason

Nuclear Magnetic Resonance (NMR) spectroscopy in an important analytical, which is useful to predict the structure of the compound. Magnetically active nucleus was identified with the aid of this technique. Since the organic compounds were made up of carbon and hydrogen in major quantity, the identification of $^{\rm{1}}{\rm{H}}$ and $^{{\rm{13}}}{\rm{C}}$ in a compound will be much helpful to identify the structure of the organic compound.

Fundamentals

The data from NMR spectroscopy was given in the form graph containing signals, which is called as NMR spectrum.

In proton NMR spectrum, number of signals observed will be equal to the number of different type of protons (chemically non-equivalent protons) existing in the structure.

In $^{{\rm{13}}}{\rm{C NMR}}$ also the number of absorption peaks equal to the number of different type of carbons present in structure.

Molecular symmetry in NMR:

The number of signals for an organic compound in NMR spectrum can be predicted from its symmetry element. For a $^{\rm{1}}{\rm{H and}}{\,^{{\rm{13}}}}{\rm{C}}$ nuclei to produce the same signal structure it must contain at least one of the symmetry elements, such as mirror plane or rotational axis. For example

The given compound doesn’t have any symmetry elements. Therefore it was identified that the given compound has eight different types of carbon atoms in it as shown below.

The given organic compound will have eight $^{{\rm{13}}}{\rm{C}}$ NMR signals.

Ans:

There are eight $^{{\bf{13}}}{\bf{C}}$ NMR signals for the given organic compound.