Chapter 16, Problem 16.66P

Interpretation Introduction

Interpretation:

In the ${}^{13}\text{C}$ NMR spectrum of $\text{1-Chloropropane}$ provided in problem $\text{16}\text{.65}$, which signals would appear in the $\text{DEPT-90}$ spectrum, which would appear as positive and negative signals in $\text{DEPT-135}$ spectrum are to be identified.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in the ${}^{13}\text{C}$ NMR equals to the number of distinct carbon atoms in the given unknown.

In a $\text{DEPT-90}$ spectra the only signals are those of carbon atoms having a single proton $\left(\text{CH}\right)$. Signals of carbons with zero, two, or three protons do not appear in a $\text{DEPT-90}$. In a $\text{DEPT-135}$ spectrum, carbon atoms with one and three protons ($\text{CH}$ and ${\text{CH}}_{\text{3}}$) produce normal signals, whereas carbons with two protons (${\text{CH}}_2$) produce negative signals that is, below the baseline. As in $\text{DEPT-90}$, signals from carbon atoms with no protons are absent in a $\text{DEPT-135}$.