Chapter 16, Problem 16.51P

Interpretation Introduction

Interpretation:

How the $\text{H}$ NMR spectra of compounds A and B differ is to be explained.

Concept introduction:

Chemically distinct protons are surrounded by different electron distributions and therefore have different values of ${\text{B}}_{\text{loc}}$. Consequently, chemically distinct protons are shielded from ${\text{B}}_{\text{ext}}$ to a different extent and will absorb photons at different frequencies – they will have different chemical shifts. The proton in ${\text{CH}}_3$ group next to a carbonyl carbon has a chemical shift of 2.1 ppm. The proton in ${\text{CH}}_3$ group next to an oxygen atom has a chemical shift of 3.3 ppm.