Question

When you have a doublet of doublets how many neighbouring hydrogen will there be?

Answer 1

Hint:. The answer is based on the concept of nuclear magnetic resonance spectra or NMR spectra which is used to observe the local magnetic fields around the nuclei and gives the information about how many neighbouring hydrogen exists for particular hydrogen or group of equivalent hydrogens.

Complete step by step answer:
- In the lower classes of chemistry, we have studied the spectroscopic concepts in organic chemistry which tells us about the identification of structure of the compound and also the functional group present in the compound by various techniques like NMR, IR and also mass spectroscopy.
We shall now see the calculation of neighbouring hydrogen based on the NMR spectra.
- NMR spectra basically tells us about the structure of the atom. There are several types of NMR like proton NMR,${}^{13}C$- NMR and some other.
- It also gives us information about the neighbouring protons or hydrogen present neighbour to another hydrogen or group of equivalent hydrogens.
- Here doublet of doublets is nothing but the pattern of four lines which results from the coupling of two protons or is caused by the coupling of hydrogen atoms to two non equivalent hydrogens.
- Because of this reason there is one neighbouring hydrogen in the distinct chemical environment as in the first order spectrum, the given absorption splits into doublet by coupling with the first proton which further splits into doublet by coupling with the second non equivalent proton.
- Thus the correct answer is one neighbouring hydrogen in the distinct chemical environment.

Note: Note that sometimes the doublets formed will overlap to give which seems to be like the triplets and these multiplets formed can be resolved by doing the experiment on a higher field instrument.