Chapter 15.SE, Problem 40AP

Interpretation Introduction

Interpretation:

The structure for a hydrocarbon with the following spectral characteristics is to be identified.

Mass spectrum: M⁺ at 120.

¹HNMR spectrum: 7.25δ (5H, broad singlet); 2.90δ (1H, septet, J=7 Hz); 1.22δ (6H, doublet, J=7 Hz).

Concept introduction:

The molecular ion peak gives the approximate molecular mass of the compound. In ¹HNMR spectrum aromatic protons give a broad peak in the range 6.5δ-8.0δ, the primary alkyl protons around 0.7δ-1.3δ, the secondary alkyl protons around 1.2δ-1.6δ, and a tertiary alkyl protons in between 1.4δ-1.8δ. The multiplicity of a signal gives an idea about the protons present in the adjacent carbons.

To identify:

The structure for a hydrocarbon with the following spectral characteristics.

Mass spectrum: M⁺ at 120. 1HNMR spectrum: 7.25δ (5H, broad singlet); 2.90δ (1H, septet, J=7 Hz); 1.22δ (6H, doublet, J=7 Hz).