Chapter 18, Problem 18.74SP

Interpretation Introduction

Interpretation: The structure of the nasty compound is to be predicted and the way the structure of the compound fits the given spectra is to be shown.

Concept introduction: In the proton NMR spectrum of ketones and aldehydes, we primarily see proton is attached to the carbonyl group (aldehyde or ketone protons) and the proton is attached to the adjacent carbon atom. The chemical shift value between $\text{δ}\text{9}$ and $\text{δ}\text{10}$ indicates the presence of aldehyde proton in proton NMR spectrum of an aldehydes.

In ultraviolet (UV) spectra of aldehydes and ketones, the strongest absorptions are the ones that results from $\text{π}$ to ${\text{π}}^{*}$ electronic transition. In the alkenes, these observations are seen at ${\text{λ}}_{\max }>200\text{nm}$ only, if carbonyl compound double bond is in conjugation with another double bond.

In IR spectrum, the carbonyl stretching $\left(\text{C}=\text{O}\right)$ of aldehyde that are in conjugation occurs around $\text{1685}{\text{cm}}^{-1}$.

To determine: The structure of the nasty compound and the way the structure of the compound fits the given spectra.