NEET 2025 Latest News Updates By NTA: Registration, Syllabus & Exam Pattern

Azo-Coupling Reaction MCQ - Practice Questions with Answers

Edited By admin | Updated on Sep 25, 2023 25:24 PM | #NEET

Quick Facts

  • Basicity of Aromatic Amines is considered one the most difficult concept.

  • Azo-Coupling Reaction is considered one of the most asked concept.

  • 44 Questions around this concept.

Solve by difficulty

Which of the following will be most stable diazonium salt \text{RN}_{2}^{+}\text{X}^{-}?

In the following reaction, the product (A)

 

In the following reaction, the product (A)

is:

NEET 2024: Cutoff (OBC, SC, ST & General Category)

NEET 2024 Admission Guidance: Personalised | Study Abroad

NEET 2025: SyllabusMost Scoring concepts NEET PYQ's (2015-24)

NEET PYQ's & Solutions: Physics | ChemistryBiology

Toluene is nitrated and the resulting product is reduced with tin and hydrochloric acid. The product so obtained is diazotised and then heated with cuprous bromide. The reaction mixture so formed contains

In the reaction    A is:

Nitrobenzene can be prepared from benzene by using a mixture of conc. HNOand conc. H2SO4 in the mixture, nitric acid acts as a/an:

The given compound of vanadium has only a spin magnetic moment of 1.73 BM.  This vanadium chloride has the formula:(At. no. of V = 23)

 

Pearson | PTE

Register now for PTE & Unlock 20% OFF : Use promo code: 'C360SPL20'. Valid till 30th NOV'24! Trusted by 3,500+ universities globally

Nitrobenzene on reaction with conc. HNO3/H2SO4 at 80 - 100°C forms which one of the following products?

The correct increasing order of basic strength for the following compounds is :

Most Scoring concepts for NEET
This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.
Download EBook

Which of the following compounds is most basic?

Concepts Covered - 4

Azo-Coupling Reaction

Benzene diazonium salts react with highly reactive compounds such as phenols and amines to form brightly coloured azo compounds. This reaction is called coupling reaction. Coupling with phenols occurs in the basic medium(pH 9-10) and that of amines occur in fairly medium(pH 4-5) at 273-298K.

Mechanism

For example,

Properties of Nitrocompounds and Mulliken Barker Test

Reduction in acidic medium
Both aliphatic and aromatic nitro compounds are reduced to corresponding primary amines with Sn/HCl or Fe/HCl by a combination of some active metals like tin, iron or zinc and conc. HCl or catalytic reduction with Ni, Pt or Pd/C. The reaction occurs as follows:

\mathrm{C_{6}H_{5}NO_{2}\: +\: 6H\: \xrightarrow[or\: Sn/HCl]{Fe/HCl}\: C_{6}H_{5}NH_{2}\: +\: 2H_{2}O}

Reduction in basic medium
Both aliphatic and aromatic nitro compounds are reduced to corresponding hydroxylamines in the neutral medium with zinc dust and NH4Cl or Al-Hg couple.

Reduction in neutral medium
Both aliphatic and aromatic nitro compounds are reduced to corresponding hydroxylamines in the neutral medium with zinc dust and NH4Cl or Al-Hg couple. The reaction occurs as follows:

\mathrm{CH_{3}CH_{2}NO_{2}\: +\: 4H\: \xrightarrow[\Delta ]{Zn/NH_{4}Cl,H_{2}O}\: CH_{3}CH_{2}NHOH\: +\: H_{2}O} 

Mulliken barker test
The test is based on the factwth a neutral agent, -NO2 is reduced to the NHOH group. The fromed hydroxylamine reduces the Tollen's reagent and gets oxidised to a nitroso compound. The reaction occurs as follows:
 

Preparation of Aromatic Nitrocompounds
  1. By nitration of benzene with a mixture of concentrated nitric acid and concentrated sulphuric acid at temperature below 330K. The temperature should not increase otherwise m-dinitrobenzene is formed. So, nitration of benzene depends upon temperature and nature of the nitrating agent used. The reaction occurs as follows:
  2. Nitrobenzene can be prepared by carrying our diazotizatin of aniline and then reacting with nitrous acid(HNO2) in the presence of cuprous oxide. The reaction occurs as follows:
    \mathrm{C_{6}H_{5}N_{2}Cl\: +\: HNO_{2}\: \overset{Cu_{2}O}{\longrightarrow}\: C_{6}H_{5}NO_{2}\: +\: N_{2}\: +HCl}
  3. Nitrobenzene can be prepared from oxidation of aniline by trifluoro acetic acid. The reaction occurs as follows:
    \mathrm{C_{6}H_{5}NH_{2}\: +\: 3[O]\: \overset{CF_{3}COOH}{\longrightarrow}\: C_{6}H_{5}NO_{2}\: +\: H_{2}O}
  4. Nitrobenzene can be prepared by the action of acetyl nitrate on benzene.
    \mathrm{C_{6}H_{5}H\: +\: CH_{3}COONO_{2}\: \rightarrow \: C_{6}H_{5}NO_{2}\: +\: CH_{3}COOH}
     
Basicity of Aromatic Amines

Aniline and other aromatic amines are far less basic than ammonia and aliphatic amines. Aniline is a weak base as it forms salts with strong mineral acids. Weaker basic nature of aniline as compared to aliphatic amines can be explained on the basis of resonance. In aliphatic amines, the non-bonding electron pair of N is localized and is fully available for coordination with a proton. On the other hand, in aniline or other aromatic amines, the non-bonding electron pair is delocalized into benzene ring by resonance and the electron donating capacity of nitrogen for protonation is considerably decreased to that of NH3 and aliphatic amines.

Lower stability of anilinium ion than aniline
Anilinium ion formed by aniline on accepting a proton is less resonance stabilized than aniline.

Thus, electron density is less on N-atom due to which aniline or other aromatic amines are less basic than aliphatic amines.

Study it with Videos

Azo-Coupling Reaction
Properties of Nitrocompounds and Mulliken Barker Test
Preparation of Aromatic Nitrocompounds

"Stay in the loop. Receive exam news, study resources, and expert advice!"

Books

Reference Books

Azo-Coupling Reaction

Chemistry Part II Textbook for Class XII

Page No. : 406

Line : 16

E-books & Sample Papers

Get Answer to all your questions

Back to top