Question

An unknown compound reacts with ethyl chloride and aluminum trichloride to form a compound that has the following ¹H NMR spectrum. What is thestructure of the compound?

Short answer

Proton NMR finds the organic molecule's structure byconsidering the proton environmentof the compound.

The number of peaks/signals in the proton NMR spectrum (graph plot between ppm value and energy absorbed) tells the number of different proton environments present in the compound.

Step-by-step solution

Proton NMR

Proton NMR finds the organic molecule's structure byconsidering the proton environmentof the compound.

The number of peaks/signals in the proton NMR spectrum (graph plot between ppm value and energy absorbed) tells the number of different proton environments present in the compound.

Structure of compound

An unknown compound reacts with ethyl chloride and aluminum trichloride to form a compound with the ¹H NMR spectrum having the unsplit signal at 7.1 that is of benzene hydrogen in the product is chemically equivalent. The triplet at 1.2 ppm of -CH₂ hydrogen and quartet at 2.6 ppm is -CH₃the hydrogen of the ethyl group.

Thus the compound form in the product is 1,4-diethylbenzene, and the unknown compound from which it is formed is ethylbenzene, shown as follows:

Formation of1,4-diethylbenzene