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All questions of Amines for ACT Exam

 Which of the following has highest boiling point?
  • a)
    (C2H5)2NH
  • b)
    C2H5N(CH3)2
  • c)
    C2H5NH(CH3)2
  • d)
    n-C4H9NH2
Correct answer is option 'D'. Can you explain this answer?

Krishna Iyer answered
The correct answer is Option D.
Because C4H9NH2 is primary amine and can form hydrogen bonding more than secondary amine (C2H5)2NH and tertiary amine C2H5N(CH3)2 . More hydrogen bonding  leads to strong bonding between the molecules, hence increases the boiling point.

Hoffmann Bromamide Degradation reaction is shown by __________.
  • a)
     ArNH2
  • b)
    ArCONH2
  • c)
    ArNO2
  • d)
    ArCH2NH2
Correct answer is option 'B'. Can you explain this answer?

Hansa Sharma answered
The Correct answer is option B
Hoffman bromamide degradation reaction is shown by ArCONH2​.
Where the aryl amide is converted to aryl amine in the presence of Br2​ and NaOH

 Nitro compounds are reduced to amines. The catalyst that is preferred is:
  • a)
    Sn + HCl
  • b)
    Fe + HCl
  • c)
    Ethanol
  • d)
    Mg + HCl
Correct answer is option 'B'. Can you explain this answer?

Hansa Sharma answered
Fe + HCl is preferred due to the following reasons:
- Scrap iron i.e Fe is cheap and commercially easily available
- FeCl2 formed will get hydrolysed and release HCl, so, HCl which is required in the reaction will be produced by itself
- Hence only small amount of HCl is required to initiate the reaction.

 In amines ,the hybridisation state of N is:
  • a)
    sp
  • b)
    sp2d
  • c)
    sp2
  • d)
    sp3
Correct answer is option 'D'. Can you explain this answer?

Riya Banerjee answered
Hybridisation of N in amine is sp3  with nitrogen having a one pair and 3 bond pair. Remember that amine is RR’R”N where R, R’ and R” may be alkyl or hydrogen.

  • a)
    Sandmeyers reaction
  • b)
    Gattermanns reaction
  • c)
    Dehydrogenation reaction
  • d)
    Esterification reaction
Correct answer is option 'B'. Can you explain this answer?

Geetika Shah answered
This reaction is called Gattermann reaction. In this reaction, Cl, Br and CN can be introduced into the benzene ring by simply treating diazonium salts with HCl, HBr, KCN. Respectively in presnce of copper powder instead of using Cu(I) salts.

 Reduction of alkanenitriles with sodium and alcohol or LiAlH4 is called:
  • a)
    Wolf-Kishner reduction
  • b)
    Rosenmund reduction
  • c)
    Mendius reaction
  • d)
    Catalytic reduction
Correct answer is option 'C'. Can you explain this answer?

Nikita Singh answered
The reaction is a Mendius reaction as because in this reaction the organic nitrile is reduced by nascent hydrogen(from sodium in ethanol) to a primary amine. (RCN+2H2=RCH2NH2).
where as LiAlH4 is a strong reducing agent and can be used as an abstract source of H neucophile.

 Pyridine is less basic than triethylamine because:
  • a)
    Pyridine has aromatic character
  • b)
    Nitrogen in pyridine is sp2 hybridized.
  • c)
    Pyridine has a cyclic system.
  • d)
    Lone pair of nitrogen in pyridine is delocalized.
Correct answer is option 'D'. Can you explain this answer?

Om Desai answered
Basicity of amines is due to availability of an unshared pair (lone pair) of electrons on nitrogen. This lone pair of electrons is available for the formation of a new bond with a proton or Lewis acid. Pyridine is less basic than triethylamine because lone pair of nitrogen in pyridine is delocalised.

 When Primary amide is treated with an aqueous solution of KOH and bromine, it gives a primary amine. The name of the reaction is:
  • a)
    Gabriel-phthalamine reaction
  • b)
    Reimer-Tiemann reaction
  • c)
    Ammonolysis
  • d)
    Hoffmann Bromamide reaction
Correct answer is option 'D'. Can you explain this answer?

Anjana Sharma answered
Hoffmann Bromamide reaction is Treatment of alkylamide with KOH and Bromine gas which converts it into alkylamine with one less carbon atom, this reaction is generally helpful in converting Carboxylic acids to amines with one less carbon atom . For reaction you may refer to internet but i can give you a hint .

Acetamide + KOH + Bromine gas —-> Alkylamine+ KBr + K2CO3 + H20 ( not sure about the products)

 Which of the following amine will form stable diazonium salt at 273-283 K ?
  • a)
    C6H5NH2
  • b)
    C6H5N(CH3)2
  • c)
    C2H5NH2
  • d)
    C6H5CH2NH2
Correct answer is option 'A'. Can you explain this answer?

Riya Banerjee answered
The correct answer is Option A.
Aromatic Primary amine will form the most stable diazonium salt because it releases water when it reacts with nitronium ions. If aliphatic primary amine reacts with nitrosonium ion it Also releases water but in this case water reacts with alkyl diazonium salt and it forms alcohol while benzene diazonium salt does not react with water at this temperature.

Replacement of diazo group by other groups is helpful in preparing those substituted aromatic compounds which cannot be prepared by
  • a)
    Direct elimination
  • b)
    Addition reaction
  • c)
    Direct substitution
  • d)
    Replacement reaction
Correct answer is option 'C'. Can you explain this answer?

Vikas Kumar answered
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.

Benzene diazonium chloride on reaction with phenol in weakly basic medium gives:
  • a)
    p-Hydroxyazobenzene
  • b)
    Benzene
  • c)
    Diphenyl ether
  • d)
    Chlorobenzene
Correct answer is option 'A'. Can you explain this answer?

Arka Das answered
**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.

The main product formed by treating an alkyl or benzyl halide with excess ammonia
  • a)
    Mixed
  • b)
    Tertiary
  • c)
    Secondary
  • d)
    Primary
Correct answer is option 'D'. Can you explain this answer?

Amita Das answered
The N in ammonia functions as the nucleophile and attacks the electrophilic C of the alkyl halide displacing the bromide and creating the new C-N bond. 
Step 2: An acid/base reaction. The base (excess ammonia) deprotonates the positive N (ammonium) center creating the alkylation product, the primary amine.

. IUPAC name of NH2CH2CH2CH2COOH is :
  • a)
    1-Aminobutanoic acid
  • b)
    4-Aminobutanoic acid
  • c)
    4-Nitrobutanoic acid
  • d)
    4-Aminopropanoic acid
Correct answer is option 'B'. Can you explain this answer?

  4     3     2    1


NH2CH2CH2 CH2   COOH  is  4-Aminobutanoic acid , here carboxy group gets preferred over amino group as a main chain.  

To convert methyl cyanide to ethylamine we use:
  • a)
    Br2
  • b)
    HNO3
  • c)
    KOH
  • d)
    LiAlH4
Correct answer is option 'D'. Can you explain this answer?

Riya Banerjee answered
LiAlH4 reduces all oxiginated functional groups to alcohol and all nitrogenated functional groups to amine thus cyanide is a nitrogenated functional group and to convert cyanide to amine LiAlH4 can be used.

 When ethanol is treated with benzene diazoniumchloride it forms:
  • a)
    Arenes
  • b)
    Ethyl alcohol
  • c)
    Amines
  • d)
    Methane
Correct answer is option 'A'. Can you explain this answer?

Om Desai answered
The correct answer is option A
When C2H5OH (ethanol) is treated with C6H5N2Cl it forms benzene.
Some mild reducing agents like C2H5OH themselves get oxidized to ethanol after reducing C6H5N2Cl to benzene.

. Acrylonitrile is the common name of:
  • a)
    CH3CH2CH2CN
  • b)
    CH3CH2CN
  • c)
    CH2=CHCN
  • d)
    CH3CN
Correct answer is option 'C'. Can you explain this answer?

Shreya Gupta answered
Acrylonitrile is an organic compound with the formula CH2CHCN. It is a colorless volatile liquid, although commercial samples can be yellow due to impurities. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile. It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. It is reactive and toxic at low doses. Acrylonitrile was first synthesized by the French chemist Charles Moureu (1863–1929) in 1893.

We can obtain ethylamine by Hoffmann bromamide reaction. The amide used in this reaction is:
  • a)
    Methanamide
  • b)
    Acetamide
  • c)
    Propanamide
  • d)
    Butanamide
Correct answer is option 'C'. Can you explain this answer?

Gunjan Lakhani answered
The correct answer is option C
CH3​CH2​CONH2​ (A)⟶ CH3​ − CH2 ​− NH2​ (B)⟶ ​CH3​ − CH2 ​− OH
In the above sequence A & B respectively are Br2​/KOH and HNO2
The first step is Hoffmann bromamide degradation reaction in which an amide (propanamide) is converted to an amine  (ethylamine) containing one carbon atom less. The reagent A is bromine in presence of KOH. In the second step, aliphatic primary amine (ethyl amine) reacts with nitrous acid (reagent B) to form aliphatic primary alcohol (ethyl alcohol).
 

 Ambident group among the following are:
  • a)
    Cyanides and Isocyanides
  • b)
    Acetone and aldehydes
  • c)
    Ethers and esters
  • d)
    Acetal and ketal
Correct answer is option 'A'. Can you explain this answer?

Nikita Singh answered
Ambident groups are those which can attack from both sides. So option a is correct because cyanides is C-N and carbon forms bonds here. Isocyanides are N-C in which nitrogen contains lone pairs which initiates reaction and attaches from nitrogen side.

 When diazonium salt solution is treated with water at a temperature of 283 K it forms?
  • a)
    Ester
  • b)
    Phenol
  • c)
    Amines
  • d)
    Alcohol
Correct answer is option 'B'. Can you explain this answer?

Vatturi Anjani answered
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.

. When diazonium salt solution is treated with KI, it forms:
  • a)
    Bromobenzene
  • b)
    Iodobenzene
  • c)
    Phenol
  • d)
    Acid
Correct answer is option 'B'. Can you explain this answer?

Kshitij Pandey answered
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

Which of the following amine gives diazonium salt on reaction with HNO2?
  • a)
    (CH3)2NH
  • b)
    CH3NH2
  • c)
    C6H5NH2
  • d)
    (CH3)3N
Correct answer is option 'C'. Can you explain this answer?

Nandini Iyer answered
C6H5NH2 reacts with HNO2 to forms diazonium salts, the reaction are as follows,
C6H5NH2 + HNO2 ------> C6H5OH + H2O + N2

p-amino azo benzene is obtained by treating diazoniumchloride with:
  • a)
    Phenol
  • b)
    Aniline
  • c)
    Alcohol
  • d)
    Benzoic acid
Correct answer is option 'B'. Can you explain this answer?

Lavanya Menon answered
p-amino azo benzene is obtained by treating diazonium chloride with aniline. The reactions are specifically acid catalyzed and involve pre‐equilibrium formation of amine and diazonium salt followed by rate‐limiting attack of the diazonium ion at a C‐atom (C‐coupling) to give the corresponding amino azo compounds.

 is a tertiary amine with IUPAC name:
  • a)
    N,N-Dimethyl-methanamine
  • b)
    N-methyl-ethanamine
  • c)
    N-Phenyl-methanamine
  • d)
    N-Methylmethanamine
Correct answer is option 'A'. Can you explain this answer?

Varsha Mangla answered
C'oz 2 methyl group (CH3) are attached to the N group and as per the rule for the amine, the naming can only be done as N,N-Dimethyl methanamine.

Which one of the following is used to increase blood pressure
  • a)
    Ephedrine
  • b)
    Novocain
  • c)
    Benadryl
  • d)
    None of these
Correct answer is option 'A'. Can you explain this answer?

Anjali Iyer answered
Correct answer is d) none of these:

1. Fludrocortisone is a medication that seems to help most types of low blood pressure. It works by promoting sodium retention by the kidney, thereby causing fluid retention and some swelling, which is necessary to improve blood pressure. 
2. Midodrine activates receptors on the smallest arteries and veins to produce an increase in blood pressure. It is used to help increase standing blood pressure in people with postural hypotension related to nervous system dysfunction.

By treating diazonium salts with cuprous cyanide or KCN and copper powder it forms:
  • a)
    Citric acid
  • b)
    Benzoic acid
  • c)
    Aryl nitrile
  • d)
    Oxalic acid
Correct answer is option 'C'. Can you explain this answer?

Rishika Patel answered
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.

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