Question

For the protons labeled Ha and Hb in the structure below, predict the characteristics of their signals in the H NMR spectrum: the approximate chemical shift, the splitting pattern, and the integration value of their signals. Approximate Integration Splitting chemical shift value O 1H H NMR signal O 1 ppm O singlet for H O doublet O 2H 2 ppm O 3H O 3-4 ppm O triplet Br O 4H O 5-6 ppm O quartet O 5H O 7-8 ppm O quintet. O 6H O multiplet H NMR signal O 1 ppm O 1H O singlet for H O 2H O 2 ppm doublet O 3-4 ppm O 3H O triplet O 5-6 ppm O quartet. 4H O 7-8 ppm O 5H O quintet O 6H O multiplet

Answer 1

The details for the 1H-NMR are as follows,

Ha ...........7-8 ppm.................doublet.....................2H

Hb ...........7-8 ppm.................triplet.....................1H

Both Ha and Hb are aromatic protons, which appears around 7-8 ppm. Ha has one hydrogen attached to adjacent carbon as neighbour, thus shows splitting pattern of doublet for 2H as their are two Ha in the molecule. Hb has two hydrogens attached to adjacent carbons on both sides as neighbour, thus shows splitting pattern of triplet for 1H.