Question

The final product of the nitration of toluene is:
a.) o-nitrotoluene
b.) m-nitrotoluene
c.) 2,4 – dinitrotoluene
d.) 2,4,6 – trinitrotoluene

Answer 1

Hint: Before answering this question, we should know that nitration of Toluene involves electrophilic aromatic substitution reaction. It involves addition of nitrate in ortho and meta position of an aromatic compound.


Complete step by step solution:
We must remember that in reactions of electrophilic aromatic substitution, the aromatic organic compounds are nitrated by a mechanism involving the attack of the electron-rich benzene ring on the nitronium ion. The formation of a nitronium ion which is the electrophile is from nitric acid and sulfuric acid. The sulphuric acid is regenerated as a product and acts as a catalyst in this reaction.
The chemical equation is illustrated below for our better understanding:

The methyl group of toluene is far more reactive than benzene in electrophilic aromatic substitution reactions. Hence, toluene undergoes nitration to give ortho and para nitro toluene isomers, but when heated it can give dinitrotoluene and ultimately the explosive trinitrotoluene.
Just as with benzene, we will get a certain amount of dinitro compound formed under the conditions of the reaction, but no significant trinitro product because the reactivity of the ring decreases for every nitro group added.

Hence, the correct answer is Option (D) 2,4,6 – trinitrotoluene.



Note:
In the laboratory, 2,4,6-trinitrotoluene is produced by a two-step process. A nitrating mixture of concentrated nitric and sulfuric acids is used to nitrate toluene to a mixture of mono- and di-nitrotoluene isomers, which is carefully cooled to maintain temperature. We then separate the nitrated toluenes, wash it with dilute sodium bicarbonate and remove oxides of nitrogen, and they are then carefully nitrated with a combination of fuming nitric acid and sulfuric acid.