How can one differentiate between singlet, doublet, and triplet peaks in NMR?

In NMR, singlet peaks represent one resonance, doublet peaks two closely spaced resonances, and triplet peaks three closely spaced resonances.

Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool used by chemists to determine the structure of molecules. It works by applying a magnetic field to a sample and then measuring the energy absorbed by the nuclei when they are exposed to radiofrequency radiation. The resulting spectrum shows peaks that correspond to different resonances, or energy levels, of the nuclei.

Singlet peaks are the simplest type of peak in an NMR spectrum. They represent a single resonance, meaning that the nucleus is in one specific energy state. This usually indicates that the atom in question is not adjacent to any other atoms of the same type, or that it is adjacent to atoms of the same type but they are all in the same chemical environment.

Doublet peaks are slightly more complex. They represent two closely spaced resonances, which usually indicates that the atom in question is adjacent to one other atom of the same type in a different chemical environment. The two peaks are of equal intensity and are separated by a specific distance, known as the coupling constant.

Triplet peaks are even more complex. They represent three closely spaced resonances, which usually indicates that the atom in question is adjacent to two other atoms of the same type in different chemical environments. The three peaks are not of equal intensity; instead, the middle peak is twice as intense as the outer peaks. This pattern is known as a 1:2:1 triplet.

In summary, the number and pattern of peaks in an NMR spectrum can provide valuable information about the structure of a molecule. Singlet peaks indicate a single resonance, doublet peaks indicate two resonances, and triplet peaks indicate three resonances. By analysing these peaks, chemists can determine the arrangement of atoms within a molecule and gain insights into its chemical behaviour.