Chapter 8, Problem 1Q

Interpretation Introduction

Interpretation:

The reason that leads to difficulty in the visualization of separation of $\text{cis-2-butene}$ and $\text{trans-2-butene}$ on thin layer chromatography plate should be explained.

Concept introduction:

Isomers (cis and trans) of $\text{but-2-ene}$ have similar composition. The principle on which the thin layer chromatography works is that two different molecules interact differently with the mobile and stationary phase.Thus, it ends up getting separated. If two similar molecules or isomers are spotted on the plate, they might end up at the same distance from the base.

Answer to Problem 1Q

Observing a separate spot of isomers of $\text{but-2-ene}$ is difficult, because before they resolve into distinct spots, it evaporates.

Explanation of Solution

$\text{But-2-ene}$ vaporizes too fast at room temperature due to very low boiling point. To obtain separate spots for the two isomers of $\text{but-2-ene}$ , the sample mixture must move upward in the TLC column. But the mixture spot marked on the TLC plate evaporates.So, identifying and visualizing the two isomers separately becomes difficult.