In aniline the NH2 group is electron donating but itself acts as a lewis base and hence H+ or NO2+ first attacks the NH2 and makes the ring electron deficient . Therefore the nitration product is major in meta isomer.

Why is meta product formed in nitration of aniline?

The anilinium group, no longer possessing a free electron pair (tied up with H^+), deactivates the aromatic ring toward electrophilic substitution,also anilinium ion which is meta directive. Hence nitration of aniline gives meta derivative along with ortho and para.

Why nitration of aniline gives substantial amount of M isomer?

In presence of these acids, most of aniline gets protonated to form ahilinium ion. Therefore, in presence of acids, the reaction mixture consist of aniline and anilinium ion. ... Thus, nitration of aniline gives a substantial amount of m-nitroaniline due to protonation of the amino group.

Why does nitration of aniline give m-nitroaniline?

Nitration of aniline in strong acidic medium also gives m-nitroaniline because. Inspite of substituents nitro group always goes to only m-position. ... In absence of substituents nitro group always goes to m-position.

Is aniline a meta?

The aniline amino group is ortho and para-directing, while meta-directing is aniline hydrogen chloride. ... The substituent is called a meta directing group if the opposite is observed.

Why Aniline gives meta products on direct Nitration: Solution with Examples

32 related questions found

Why is Acetanilide nitration not aniline?

Transcribed image text: Acetanilide is used instead of aniline for the nitration because aniline has an unwanted side reaction. ... The product of the third reaction is a diazonium salt, which is not isolated but is used immediately.

Why nitration of aniline is carried out after acylation?

(a) Acylation activates the -NH2 group.

Why pKb of aniline is more than that of methylamine?

pKb of aniline is more than that of methylamine, why. Ans. Because aniline is less basic than methylamine due to stabilisation lone pair of N by resonance effect.

What is obtained on acetylation of aniline?

So, the reaction by which acetanilide can be formed is by acetylation of aniline. In the acetylation of amide, aniline reacts with ethanoic anhydride in presence of base like pyridine to form acetanilide. So, acetanilide can be produced by acetylation of aniline. Hence, the correct answer is option C.

How aniline is nitrated?

In case of nitration in aniline, the Nitric Acid protonates the aniline to form the Anilinium ion. Now since the nitrogen atom has no lone pair to conjugate, it has no mesomeric effect on the ring, the but as nitrogen is now protonated, it has a high negative inductive effect.

Which gives a meta nitro compound as the main product of nitration?

Explanation: Nitration is achieved using a mixture of nitric acid and sulfuric acid, which produce the nitronium ion (NO₂⁺), which the electrophile.

When aniline is nitrated by nitric acid gives?

Direct nitration of aniline with nitric acid gives a complex mixture of mono, di- and tri-nitro compounds and oxidation products. If −NH2 group is protected by acetylation and then nitrated with nitrating mixture, p-isomer is the main product.

Why is acetylation of aniline necessary prior to nitration?

Why is group of aniline acetylated before carrying out nitration? Answer: Due to the strong activating effect of group, aromatic amines readily undergo electrophilic substitution reactions and it is difficult to stop the reaction at the monosubstitution stage.

What is the purpose of acetylation?

Proteins that replicate DNA and repair damaged genetic material are created directly by acetylation. Acetylation also helps in DNA transcription. Acetylation determines the energy that proteins use during duplication and this determines the accuracy of copying the genes.

What is the principle on the acetylation of Acetanilide?

Principle: Acetanilide is synthesized from aniline by acetylating it with acetic anhydride in presence of glacial acetic acid. Aniline or phenylamine is a primary amine and basic in nature. Acetic anhydride, an anhydride of acetic acid, acts here as a source of acyl group.

Why does aniline undergo Friedel's reaction?

For Aniline, the Friedel – Crafts reaction does not occur. Due to the lone pair of electrons on N, aniline is a strong lewis base. ... Hence, aniline does not undergo Friedel – Crafts reaction.

Why ethylamine is more basic than methylamine?

Hi, Jean, Ethyl group has a stronger electron donating effect than a methyl and therefore will push more electron density towards the nitrogen, making ethylamine a stronger base.

What is pKb value?

Updated July 17, 2019. pK_b is the negative base-10 logarithm of the base dissociation constant (K_b) of a solution. It is used to determine the strength of a base or alkaline solution. pKb = -log₁₀K_b. The lower the pK_b value, the stronger the base.

Is NH2 ortho and para directing?

- NH2 group of aniline is ortho, para directing in electrophilic substitutions.

What is nitration Acetanilide?

The organic compound p-nitroacetanilide is prepared from acetanilide through nitration. When acetanilide is treated with nitrating mixture that is a mixture of nitric acid and sulphuric acid p-nitroacetanilide is formed. Along with p-nitroacetanilide, o-nitroacetanilide is also formed as a minor product.

What is the purpose of acetanilide in the preparation?

Acetanilide is used as an inhibitor of hydrogen peroxide decomposition and is used to stabilize cellulose ester varnishes. It has also found uses in the intermediation in rubber accelerator synthesis, dyes and dye intermediate synthesis, and camphor synthesis.

Why glacial acetic acid is used in preparation of acetanilide?

Theory: Acetanilide is prepared from aniline when it reacts with acetic anhydride/glacial acetic acid in the presence of zinc dust. ... Zinc is used to prevent the oxidation of aniline during the chemical reaction. Acetanilide is medicinally important and it is used as febrifuge.

Why is acetylation necessary for aniline?

Acetanilide is prepared from aniline using an acetylation reaction. Acetylation is often used to place an acetyl protecting group on primary or secondary amines to reduce their reactivity toward oxidizing agents or electrophiles.

Why is aniline converted into acetanilide before nitration give two reasons?

Why is aniline converted into acetanilide before nitration? Answer: During direct nitration aniline is converted to anilinium ion which is ring deactivating and meta directing group. Hence, in order to retain it ortho/para directing group is converted into acetanilide.