Chapter 14.20, Problem 42P

Interpretation Introduction

Interpretation:

The proton-coupled ${}^{\text{13}}\text{C NMR}$ spectrum for the given compounds has to be described and also relative positions of the signals has to be indicated.

Concept introduction:

The signals in the spectrum of a compound are proportional to the number of carbons that are present in the different environment within the molecule. The carbon which is present in the electron-rich environment shows a signal at a lower frequency and vice-versa. Therefore, the carbons that are present nearest to the electron-withdrawing groups produce a high-frequency signal.

The ${}^{\text{13}}\text{C NMR}$ spectra in which splitting of the signal for carbon due to the protons attached to that carbon also considered is called proton-coupled ${}^{\text{13}}\text{C NMR}$ spectra. The splitting of the signal is determined according to the $\left(N+1\right)$ rule.

The coupling between the carbon and the protons attached to it is called heteronuclear coupling.