Chapter 9, Problem 19PP

Interpretation Introduction

Interpretation:

Thechemical formula and the structure for the given mass spectrum and ${}^1\text{H}-\text{NMR}$ spectrum details are to be determined.

Concept introduction:

Mass spectrometry is the detection of ions on the basis of their weights and charges and their abundance.

Mass spectroscopy is a graph with the mass ($m/z$) of ions on the $x-\text{axis}$, where m is the mass of the ion and z is the charge of the ion, and their abundance on the $y-\text{axis}$.

Molecular ions formed by EI mass spectrometry are high energy species. Cleavage of a single bond produces a cation and a radical. The Cation can be detected using positive ion mass spectrometry and since the radical is not charged, it will be undetected.

Chain branching or cleavage of a single bond at branch points will occur such that the carbocation formed is more stable.

Carbon-carbon bonds adjacent to atoms with unshared electron pair break readily to form carbocations which are stabilized due to resonance.

Nuclear magnetic resonance spectroscopy is a graph showing the characteristic energy absorption frequencies and intensities of a compound under a magnetic field.

Chemical shifts are the positions of signals along the x-axis in the nuclear magnetic spectroscopy. It gives an idea of how many different hydrogens are present in a given H-NMR for a particular compound.

$\text{Number of peaks}=n+1$, where $n$ is the number of vicinal and geminal hydrogen atoms that are unequal to the number of hydrogen atoms producing the signal.