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Questions Related to chemistry

Reaction at ${ 0-5 }^{ 0 }C$ between aniline, ${ NaNO } { 2 }$ and HCl is known as___________

chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. Suphonation of benzene

  2. Acylation of aniline

  3. Alkylation of aniline

  4. Diazotisation

Show answer
Correct Option: D
Explanation:

This is the diazotization reaction.


The reaction goes as follows :
$PhNH _{2} + NaNO _{2} + HCl \rightarrow PhN _{2}^{+} Cl^{-}$

The benzendiazonium salt thus formed acts as a synthetic intermediate and can be used to synthesize a wide variety of substituted benzene compounds.

For example,
$PhN _{2}^{+} Cl^{-} + CuCN \rightarrow PhCN$ (cyanobenzene)
$PhN _{2}^{+} Cl^{-} + CuI (KI) \rightarrow PhI$ (iodobenzene)

Option D is correct.

Aniline when treated with $NaNO { 2 }$ and $HCl$ at $0- { 5 }^{ 0 }C$ gives ___________ as a product.

chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. chloroaniline

  2. benzene diazonium chloride

  3. chlorobenzene

  4. dichlorobenzene

Show answer
Correct Option: B
Explanation:

Aniline reacts with sodium nitrite and HCl in cold condition to form benzene diazonium chloride.
$\underset {aniline} {{ C } _{ 6 }{ H } _{ 5 }{ NH } _{ 2 }}\xrightarrow [ { NaNO } _{ 2 } ]{ HCl } \underset {benzene diazonium chloride} {[C _6H _5-N _2^+Cl^-]}$

Which of the following amines will form stable diazonium salt at 273-283 K? 

chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. $\displaystyle { C } _{ 2 }{ H } _{ 5 }{ NH } _{ 2 }$

  2. $\displaystyle { C } _{ 6 }{ H } _{ 5 }{ NH } _{ 2 }$

  3. $\displaystyle { C } _{ 6 }{ H } _{ 5 }{ CH } _{ 2 }{ NH } _{ 2 }$

  4. $\displaystyle { C } _{ 6 }{ H } _{ 5 }{ N\left( { CH } _{ 3 } \right) } _{ 2 }$

Show answer
Correct Option: B

Diazonium salts are used at a very lower temperature because:

chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. they are poisonous at room temperature

  2. they are highly unstable at room temperature

  3. they are highly volatile at room temperature

  4. none of these

Show answer
Correct Option: B
Explanation:

Diazonium salt is used at very low temperature because of the fact that at the higher temperature they are unstable, as at higher temperature $N _2$ can leave out.

Diazonium salts are used:

chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. after storing for a few days after preparation

  2. immediately after its preparation

  3. after storing for $2-3$ hours

  4. difficult to prepare commercially

Show answer
Correct Option: B
Explanation:

Diazonium salts are light sensitive and break down under near UV or violet light.This is why it is used immedietly after being prepared so that it does not loses its properties.

What makes diazonium ion one of the best leaving group of organic chemistry? 

chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. Half filled electronic configuration of nitrogen atom

  2. High electronegativity of nitrogen atom

  3. Very high stability of dinitrogen molecule in the atmosphere

  4. Weaker $C-N$ bond

Show answer
Correct Option: C
Explanation:

Diazonium ion is one of best leaving group of organic chemistry because of very high stability of dinitrogen molecule in the atmosphere.

What is the molarity of 0.2 N Na2 CO3 solution ?
chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. 0.1M

  2. 0M

  3. 0.4M

  4. 0.2M

Show answer
Correct Option: A

Diazomethane was photolysed to generate singlet carbine which was treated with cis-2-butene. The main product(s) of the reaction is/are:

chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. cis-1, 2-dimethylcyclopropane

  2. trans-1, 2-dimethylcyclopropane

  3. mixture of $(A)$ and $(B)$

  4. Ethylcyclopropane

Show answer
Correct Option: A
Explanation:

Solution:- (A) cis-$1,2$-dimethylcyclopropane

$\underset{\text{Diazomethane}}{C{H} _{2}-\overset{+}{N}={N}^{-}} \xrightarrow[-N \equiv N]{h \nu} \underset{\text{Singlet carbene} \left( \text{Methylene} \right)}{:C{H} _{2}}$
The addition of methylene would yield trans-$1,2$-dimethylcyclopropane from trans-$2$-butene and cis-$1,2$-dimethylcyclopropane from cis-$2$-butene.

Which of the following diazonium salt is relatively stable of $0-5^\circ C$- :

chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. $CH _{3}CH _2N\equiv N\left. \right } ^\oplus Cl^{-} $

  2. $CH _{3}-C(CH _{3}) _{2}-N\equiv N\left. \right } ^\oplus Cl^{-} $

  3. $CH _{3}-N\equiv N\left. \right } ^\oplus Cl^{-} $

  4. $(CH _{3}) _{3}C-N\equiv N\left. \right } ^\oplus Cl^{-} $

Show answer
Correct Option: C
Explanation:

The diazonium salt  $CH _{3}-N\equiv N\left.  \right } ^\oplus Cl^{-}$ obtained by treatment of methylamine with nitrous acid is relatively stable at $0-5^\circ C$.

Which of the following diazonium salt is relatively stable at $\displaystyle 0-5^{\circ}$C?

chemistry amines introduction to diazonium salts structure, preparation and physical properties of diazonium salts diazonium salts

  1. $\displaystyle CH _{3}-N\equiv N \left. \right }^{\oplus }Cl^{-}$

  2. $\displaystyle CH _{3}C\left ( CH _{3} \right )-N\equiv N \left. \right }^{\oplus }Cl^{-}$

  3. $\displaystyle C _{6}H _{5}-N\equiv N \left. \right }^{\oplus }Cl^{-}$

  4. $\displaystyle \left ( CH _{3} \right ) _{3}C-N\equiv N \left. \right }^{\oplus }Cl^{-}$

Show answer
Correct Option: C
Explanation:

Diazonium salts obtained from aliphatic primary amines are unstable. Those obtained from aromatic primary amines are relatively stable.
Benzene diazonium chloride $(\displaystyle C _{6}H _{5}-N\equiv N \left.  \right }^{\oplus }Cl^{-})$ is obtained from aromatic primary amine. Hence, it is relatively stable.