Chapter 9, Problem 16PP

Interpretation Introduction

Interpretation:

The structures for the isomers A, B, and C of the compound with molecular formula, C₅H₁₁ Br are to be interpreted from the given DEPT ${}^{13}\text{C}-\text{NMR}$ spectra.

Concept introduction:

DEPT stands for distortionless enhancement by polarization transfer. DEPT ${}^{13}\text{C}-\text{NMR}$ is used to indicate the number of hydrogen atoms that are bonded to each carbon while providing the information of chemical shift in a broadband proton-decoupled ${}^{13}\text{C}-\text{NMR}$ spectrum. The carbon signals in a DEPT spectrum are classified as ${\text{CH}}_3,{\text{CH}}_2,\text{CH or C}$ accordingly.

Presence of the electronegative compounds like halogens or oxygen or sulfur elements will downfield the signal, i.e., the chemical shift will occur at higher δ than the unsubstituted carbons.