Question

Compound A, C8H10, undergoes nitration to give 2 products. The 1H NMR spectrum of A shows a complex five-proton multiplet at 7.27-7.40 δ, a two-proton quartet at 2.60 δ, and a three-proton triplet at 1.25 δ. What is the structure of A?

Answer 1

According to the given spectrum datas, the compound A contains a six-membered carbon ring where 1 proton is substituted with a group (-CH2CH3) (an activating group) . The most obvious signals for rest of the five protons in this spectrum is the splitting into multiplets and the signals emitted by the -CH3 proton is triplet at 1.25ppm and the signal from the -CH2 proton is a quartet at 2.60ppm.

Regarding to the reaction of nitration, you get a mixture of mainly 2 isomers : 2- nitroethylbenzene and 4- nitroethylbenzene , As Ethyl groups are said to be 2,4-directing.

Thus, the structure of compound A must be the Ethylbenzene.