What happens when aniline undergoes nitration in strongly acidic medium?

Nitration of aniline in strong acidic medium also gives m-nitroaniline because. Inspite of substituents nitro group always goes to only m-position. In electrophilic substitution reactions amino group is meta directive. In acidic (strong) medium aniline is present as anilinium ion.

What happens when aniline undergo nitration?

In nitration of aniline in strong acid (HNO3, H2SO4) aniline changes to anillium ion . Anillium withdraws electron density. Its effect is felt maximum at ortho followed by meta and then para position. Consequently very little of ortho nitrated product is formed.

Which product is obtained by nitration of aniline?

As a result, when the nitration of aniline is carried out, it not only gives nitration products but also some oxidation products. However, under controlled conditions, if the nitration of aniline is carried out, then the major products are p-nitroaniline and m-nitroaniline.

Why nitration of aniline is difficult?

The nitration of aniline is difficult because aniline gets oxidised into protonated aniline. This aniline type gives 47% of m-nitroaniline.

Why does aniline on nitration gives m-nitroaniline?

(iv) Although amino group is o, p− directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline. (v) Aniline does not undergo Friedel-Crafts reaction. (vi) Diazonium salts of aromatic amines are more stable than those of aliphatic amines.

Why Anilinium is meta directing?

Anilinium ion due to the positive charge on it shows -I effect so it will not remain as O, P-directing towards strong acid. It will behave as meta-directing as -I effect is more on ortho(O) and para (P) position and less on meta so when an electrophile attacks, it attacks faster on meta- position.

What is the nitration of aniline write the chemical reaction?

Nitration: Direct nitration of aniline yields (p-nitroaniline) a mixture of ortho, meta, and para nitroanilines. In an acidic medium the -NH2 group is protonated to the -N+H3 group which is meta-directing and deactivating. Hence, a considerable amount of m-nitroaniline is obtained.

Why aniline is meta directing?

Nitration is carried out in an acidic medium. In a strongly acidic medium, aniline is protonated to give anilinium ion (which is meta-directing). For this reason, aniline on nitration gives a substantial amount of m-nitroaniline.

Why meta product is formed during nitration of aniline?

Aniline reacts with acid to give anilinium ion which deactivates the ring towards electrophilic substitution especially at para and ortho positions. However, meta position is not deactivated. Hence more meta product is formed.

Why should we protect group before nitration of aniline?

The hurdles for the nitration of aniline are overcome by the protection of amino group by acetylation. The acetyl group reduces the reactivity of the ring and thus its oxidation does not occur easily with nitric acid HNO3.

Why is nitration done at low temperatures?

The nitration of methylbenzene (toluene) Methylbenzene reacts rather faster than benzene – in nitration, the reaction is about 25 times faster. That means that you would use a lower temperature to prevent more than one nitro group being substituted – in this case, 30°C rather than 50°C.

What happens when aniline reacts with k2cr2o7?

Oxidation of aniline with acidified potassium dichromate gives p-benzoquinone.