Chapter 16, Problem 16.19P

Interpretation Introduction

Interpretation:

An unknown compound produces a $\text{1H}$ NMR spectrum that has just two signals, each of which is a singlet. The compound to which the spectrum is consistent with is to be identified from the given structures of compounds $\text{1-4}$.

Concept introduction:

The separation of NMR peaks into number of smaller peaks is called as splitting of NMR peaks. It occurs due to the effect of the magnetic field of one nucleus on other adjacent or neighboring nuclei. This means the coupling of the spin states of one nucleus with the spin states of adjacent or neighboring nuclei, thus called spin-spin coupling. Therefore, the splitting is caused by the spin-spin coupling. The chemically distinct protons are called non-equivalent protons and have different chemical shift. The non-equivalent protons can couple each other’s signal whereas equivalent protons do not. The multiplicity of the peak depends on the number of neighboring protons, which can be determined by $\text{(N+1)}$ rule, where N is the number of neighboring protons. If the signal for a particular proton appears as singlet, it indicates that the proton has no neighboring protons.