Question

Question: (Another true story.) A student who was checking into her lab desk found an unlabeled sample from a previous student. She was asked to identify the sample. She did an IR spectrum and declared, “It looks like an alkane.” But it seemed too reactive to be an alkane, so she did a GC–MS. The mass spectrum is shown next. Identify the compound as far as you can, and state what part of your identification is uncertain. Propose fragments corresponding to the numbered peaks.

Short answer

Answer

The unknown compound is 1-iodo-3-methylbutyne

Step-by-step solution

Introduction

The graph between the intensity (abundance) and $\frac{m}{z}$(mass to charge ratio) values of the ions is known as the mass spectrum. It is highly useful in predicting the structure of the given unknown compounds.

Explanation

From the mass spectrum, it can be said that no chlorine (Cl) or bromine (Br) are present in the unknown compound since isotopic peaks are not seen. No peak at value of$\frac{m}{z}$ indicates the absence of benzene ring in the molecule. Again, the peak at value of $\frac{m}{z}$indicates the presence of iodine in the molecule. Lastly, the peak at value of $\frac{m}{z}$shows the presence of isopropyl group. Therefore, the unknown compound will be

The structure of can be drawn as: