All questions of Amines for NEET Exam

C It is true

This reaction is unique this is only reaction in which idobenzene formed by diaazonium salt , to make idobenzene first we make diaazonium salt by aniline then we treated diaazonium salt with ki
C6H5N2Cl(diaazonium salt)+KI=C6H5I

Replacement of diazo group by other groups is helpful in preparing those substituted aromatic compounds which cannot be prepared by direct substitution. ... The cyano group usually cannot be introduced by nucleophilic substitution of haloarenes, but such compounds can be easily prepared from diazonium salts.

Yes as when the temperature of the diazonium salt is allowed to rise upto 283K then the salt is reduced to phenol releasing N2 and hydrochloric acid as the by-products.

**Benzene diazonium chloride**

Benzene diazonium chloride (C6H5N2Cl) is an organic compound that is commonly used in diazotization reactions. It is formed by the reaction of aniline (C6H5NH2) with nitrous acid (HNO2) in the presence of hydrochloric acid (HCl).

**Reaction with Phenol**

When benzene diazonium chloride reacts with phenol (C6H5OH) in a weakly basic medium, it undergoes a substitution reaction known as the Sandmeyer reaction. This reaction involves the replacement of the diazonium group (-N2Cl) with the phenolic group (-OH) to form a new compound.

**Formation of p-Hydroxyazobenzene**

The reaction between benzene diazonium chloride and phenol results in the formation of p-hydroxyazobenzene (C12H10N2O), which is the correct answer (option A).

The reaction proceeds as follows:

1. The weakly basic medium provides the necessary conditions for the reaction to occur. It helps in the deprotonation of phenol to form the phenoxide ion (C6H5O-).

2. The diazonium group of benzene diazonium chloride is highly reactive and undergoes nucleophilic substitution. The nitrogen atom of the diazonium group attacks the phenoxide ion, leading to the formation of a new carbon-nitrogen bond.

3. The chlorine atom attached to the nitrogen atom is replaced by the phenoxide group, resulting in the formation of p-hydroxyazobenzene.

The reaction can be represented by the following equation:

C6H5N2Cl + C6H5O- → C12H10N2O + Cl-

**Explanation of Other Options**

Option B: Benzenedoes not participate in the reaction. It remains unchanged.

Option C: Diphenyl ether is not formed in this reaction. It involves the formation of a carbon-oxygen bond between two phenyl groups, which is not observed in the given reaction.

Option D: Chlorobenzene is not formed in this reaction. The chlorine atom from the diazonium chloride is replaced by the phenoxide group, not by another chlorine atom.

Thus, the correct answer is option A: p-Hydroxyazobenzene.

Formation of Aryl Nitrile from Diazonium Salts

Diazonium salts are compounds containing a positively charged nitrogen atom that is linked to an aromatic ring. These salts are often used in organic synthesis as a source of the aryl group. When treated with cuprous cyanide or KCN and copper powder, diazonium salts undergo a reaction known as Sandmeyer reaction, which forms aryl nitriles.

Reaction Mechanism

The reaction mechanism involves several steps:

1. Formation of Copper(I) Salt

First, cuprous cyanide or KCN is added to the diazonium salt solution to form a copper(I) salt. The copper(I) salt plays a crucial role in the reaction by catalyzing the formation of the aryl nitrile.

2. Formation of Aryl Copper(I) Intermediate

Next, copper powder is added to the reaction mixture, which reduces the copper(I) salt to copper metal. The copper metal then reacts with the diazonium salt to form an aryl copper(I) intermediate.

3. Formation of Aryl Cyanide

The aryl copper(I) intermediate then reacts with the cyanide ion from the cuprous cyanide or KCN to form the aryl cyanide. The reaction releases copper metal, which can then react with more diazonium salt to form more aryl copper(I) intermediate.

Overall Reaction

The overall reaction can be represented as follows:

ArN2+X- + CuCN/KCN → [CuX] + N2 + ArCu + HX
ArCu + CN- → ArCN + Cu

Where Ar represents the aryl group, X represents the anion of the diazonium salt, and HX represents the acid formed in the reaction.

Conclusion

In conclusion, the treatment of diazonium salts with cuprous cyanide or KCN and copper powder forms aryl nitriles through the Sandmeyer reaction. This reaction is an important method for the synthesis of aryl nitriles, which have a variety of applications in organic synthesis and industry.

Correct option is b because as there is lone pair on nitrogen they possess a lone pair that can be donated that's why amines are bases

The Hofmann Elimination is an elimination reaction that forms C-C double (pi) bonds that specifically occurs when the leaving group is NR3 [note] It proceeds through an E2 mechanism. Although the key concepts are no different than one learns in the chapter on elimination from way back in Org 1, it is often included in Org 2 as part of the grab-bag chapter on amines. Because, well… nitrogen.

A diazonium salt is an organic compound that contains a nitrogen-nitrogen triple bond and some other generic side group that could be either alkyl (an alkane derivative) or aryl (benzene ring). The 'salt' portion of the name comes from the fact that the diazo (meaning 'di-nitrogen') portion of the compound is present as its ionic salt, with a chloride ion being a typical counter-ion for the positively charged nitrogen atom.

As the number of alkyl group increases, due to +I effect the basicity of amines increases.

Assertion: Nitrating mixture used for carrying out nitration of benzene consists of concentrated HNO3 and concentrated H2SO4.
Reason: In the presence of H2SO4, HNO3 acts as a base and produces NO2 ions.

Explanation:
The nitration of benzene is a chemical reaction in which a nitro group (-NO2) is introduced into the benzene ring. This reaction is carried out using a nitrating mixture, which typically consists of concentrated nitric acid (HNO3) and concentrated sulfuric acid (H2SO4).

Reasoning:
The presence of concentrated sulfuric acid (H2SO4) in the nitrating mixture is crucial for the nitration reaction. H2SO4 acts as a catalyst and plays a vital role in the reaction. When HNO3 is mixed with H2SO4, it forms an intermediate species called nitronium ion (NO2+). This nitronium ion is highly reactive and serves as an electrophile in the nitration reaction.

Assertion Explanation:
The assertion states that the nitrating mixture used for benzene nitration consists of concentrated HNO3 and concentrated H2SO4. This is true because both acids are essential for the successful nitration of benzene. Concentrated HNO3 provides the nitro group, and concentrated H2SO4 acts as a catalyst and helps in the formation of the electrophilic nitronium ion.

Reason Explanation:
The reason given is that in the presence of H2SO4, HNO3 acts as a base and produces NO2 ions. This statement is partially correct. HNO3 is not acting as a base in this reaction but rather as a reactant. H2SO4, on the other hand, acts as a catalyst and facilitates the formation of the nitronium ion (NO2+), which is responsible for the nitration of benzene.

Conclusion:
Both the assertion and the reason are correct. However, the reason is not a correct explanation of the assertion. The reason incorrectly states that HNO3 acts as a base in the presence of H2SO4, while in reality, it acts as a reactant to form the nitronium ion. Therefore, the correct answer is option 'b'.

Formation of Azo Compound

An azo compound is formed when benzene diazonium chloride reacts with 2,4,6-trimethylphenol and phenol. The reaction involves the substitution of diazonium group (-N2+) with the hydroxyl group (-OH) of the phenol. The reaction is called diazotization.

Diazotization Reaction

Diazotization is a chemical reaction that involves the conversion of an aromatic primary amine to a diazonium salt by the action of nitrous acid. It is a two-step process that involves the formation of a diazonium intermediate, which then reacts with a nucleophile to form the final product.

Step 1: Diazotization of Aromatic Primary Amine

In the first step of diazotization, an aromatic primary amine is treated with nitrous acid (HNO2) to form a diazonium salt. The reaction can be represented as:

R-NH2 + HNO2 → R-N2+Cl- + H2O

where R represents the aromatic group.

Step 2: Reaction with Nucleophile

In the second step, the diazonium salt reacts with a nucleophile (such as phenol or 2,4,6-trimethylphenol) to form the final product, which is an azo compound. The reaction can be represented as:

R-N2+Cl- + Ar-OH → R-N=N-Ar + HCl + H2O

where Ar represents the aromatic ring.

Formation of Azo Compound from Benzene Diazonium Chloride

When benzene diazonium chloride reacts with 2,4,6-trimethylphenol or phenol, an azo compound is formed. The reaction can be represented as:

C6H5-N2+Cl- + Ar-OH → C6H5-N=N-Ar + HCl + H2O

where Ar represents the aromatic ring of 2,4,6-trimethylphenol or phenol.

Therefore, option B (Both A and B) is the correct answer as both 2,4,6-trimethylphenol and phenol can react with benzene diazonium chloride to form azo compounds.

Acetylation of aniline results in decrease of electron density on nitrogen hence acetanilide is less basic than aniline.