Chapter 16, Problem 16.81P

Interpretation Introduction

Interpretation:

The structure for the compound is to be drawn based on the distinct signals in its ${}^1\text{H}$ NMR and the mass spectrum.

Concept introduction:

In ^{${}^1\text{H}$} NMR spectroscopy, protons in different environments within a molecule have different chemical shifts, that is, they experience different degrees of shielding.

In addition to chemical shift, a ${}^1\text{H}$ NMR spectrum provides structural information based on Number of signals, which tells how many different kinds of protons are there; Integrated areas, which tells the ratios of the various kinds of protons, and Splitting pattern, which gives information about the number of protons that are within two or three bonds of the one giving the signal. The ideal range for alkane protons is $\text{δ}0.9\text{- δ}1.4$.

The mass spectrum of a compound is often represented as a bar graph with m/z on the x axis (where m is in atomic mass units, u) and the relative abundance of ions at each m/z on the y axis. The mass of each ion is just the mass of the atoms that make it up. The ${\text{M}}^{\text{+}}$ peak of a mass spectrum is taken to be the compound’s molecular mass. The presence of bromine, chlorine, or sulfur can be identified by the relative intensity of $\text{M + 2}$ peak.