Question

Nitration of which of the following compounds is difficult?
(A) Benzene
(B) Nitrobenzene
(C) Toluene
(D) Phenol

Answer 1

Hint: As we know that nitration is a process where we can introduce a nitro group into an organic compound where nitrogen is attached with oxygen on one hand and carbon on the other hand. Aromatic nitro compounds are generally prepared by direct nitration of arenes with nitrate mixture.

Complete answer:As we know that nitration is a process where we can introduce a nitro group into an organic compound where nitrogen is attached with oxygen on one hand and carbon on the other hand. Aromatic nitro compounds are generally prepared by direct nitration of arenes with nitrate mixture.
Talking about Benzene, we know that benzene can undergo nitration reaction in the presence of concentrated nitric acid and concentrated sulphuric acid mixture leading to the formation of nitrobenzene and releasing one molecule of water. So it can easily undergo nitration.
Next let us talk about nitrobenzene, we know that nitrobenzene possess one an electron withdrawing group which is the nitro group and it also do not possess any lone pair of electrons which it can donate, so it becomes less prone to electrophile attack and therefore it cannot undergo nitration.
Next we have Toluene, as we know that the ortho and para position carbons are active in toluene so when it is treated with the mixture of concentrated nitric acid and concentrated sulphuric acid, it will undergo nitration and results in the trinitrotoluene. So it is also correct.
Lastly we have phenol which again has its ortho and para carbons free and active so they will react with the nitration mixture and hence it is also a correct answer.

Therefore, from the above explanation we can say that the correct answer is (B).

Note:Remember that because of the presence of lone pairs of electrons in compounds like phenol, the stability of the compound is maximum at ortho and para position of the benzene rings which basically make them active and reactive. Similarly, in toluene the alkyl group is directly attached with the benzene ring which increases its electron density at the ortho and para positions.