Chapter 22, Problem 22.65P

Interpretation Introduction

Interpretation:

By using the given IR and NMR spectrum of the product, the structure of the product and mechanism of the given reaction is to be determined.

Concept introduction:

In intramolecular Friedel-crafts acylation reaction is carried out in the presence of Lewis acid like ${\text{AlCl}}_{\text{3}}$ and acyl halide. The formation of the ring is taking place in this reaction.

Clemmensen reagent $\text{HCl},\text{Zn}\left(\text{Hg}\right)$ is used for the reduction of the carbonyl group $\left(\text{C}=\text{O}\right)$ to ${\text{CH}}_{\text{2}}$ group.

The NMR signal is present at $\text{7-7}\text{.1δ}$ indicates the presence of aromatic hydrogens. The NMR signal at $\text{2}\text{.6-2}\text{.8δ}$ indicates the presence of four benzylic protons. The NMR signal at $\text{1}\text{.6-1}\text{.8δ}$ indicates the presence of aliphatic protons attaches to the benzylic carbon.

In IR spectrum clear aromatic stretching bands at ${\text{3050 cm}}^{\text{-1}}\left(\text{C-H}\right)$ and ${\text{1600-1450 cm}}^{\text{-1}}\left(\text{C=C}\right)$ as well as a strong bending band at $\text{75}0{\text{ cm}}^{-\text{1 }}$ indicating the ortho-substituted aromatic ring.