Tag: introduction to diazonium salts

Questions Related to introduction to diazonium salts

Which of the following compounds will not undergo azo coupling reaction with benzene diazonium chloride?

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

  1. Aniline

  2. Phenol

  3. Anisole

  4. Nitrobenzene

Show answer
Correct Option: D
Explanation:

Diazonium cation is weak electrophile and hence it reacts with electron rich compounds containing electron donating groups such as $-OH$, $-NH _2$ and $OCH _3$ groups and not with compounds containing electron withdrawing groups such as $-NO _2$ etc.


Hence,option D is correct.

Which of the following diazonium salt is relatively stable of $0-5^o$C?

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

  1. $CH _3CH _2N\equiv N}^{\oplus}Cl^-$

  2. $CH _3-C(CH _3) _2-N\equiv N}^{\oplus} Cl^-$

  3. $CH _3-N\equiv N}^{\oplus}Cl^-$

  4. $(CH _3) _3C-N\equiv N}^{\oplus}Cl^-$

Show answer
Correct Option: C

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

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

  1. ${ CH } _{ 3 }-N\equiv N{ } }^{ \oplus }C{ l }^{ - }$

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

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

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

Show answer
Correct Option: D
Explanation:

The $+I$ effect which stabilizes the ${ N }^{ + }$ion is in the following order ${ C } _{ 6 }{ H } _{ 5 }-<{ CH } _{ 3 }-<{ \left( { CH } _{ 3 } \right)  } _{ 2 }-<{ \left( { CH } _{ 3 } \right)  } _{ 3 }$

$\therefore $ The ${ \left{ { \left( { CH } _{ 3 } \right)  } _{ 3 }C-N\equiv N \right}  }^{ + }{ Cl }^{ - }$ is most stable

Which of the following is an Incorrect statement about benzenediazonium chloride?

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

  1. It is prepared by the reaction of aniline with nitrous acid at 273-278 K

  2. It is a colourless crystalline solid

  3. Alkyl diazonium salts are more stable than arenediazonium salts

  4. Benzene diazonium fluoroborate is water insoluble & stable at room temperature

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Correct Option: C

For the successful diazotisation of arylamines, how many mole of mineral acid $(HCl \quad or \quad H _2SO _4 )$ are required for each mole of the amine?

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

  1. 1

  2. 2

  3. 3

  4. 4

Show answer
Correct Option: C

In an analytical determination of arsenic, a solution containing arsenious acid, $ H _{3}AsO _{4},$ KI and a small amount of starch is electrolysed. The electrolysis produces free $I _{2}$ from $ I^{-}$ ions and the $ I _{2}$ immediately oxidizes the arsenious acid to hydrogen arsenate ion, $ HAsO _{4}^{2-}.$
$ I _{2}+H _{3}AsO _{3}+H _{2}O \rightarrow 2I^{-} + HAsO _{4}^{2-}+4H^{+}$
When the oxidation of arsenic is complete, the free iodine blue colour. If during a particular run, it takes 96.5 s for a current of 10.0 mA to give an end point (indicated by the blue colour),how many g of arsenic are present in the solution. (As = 75)

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

  1. $ 6.3 \times 10^{-4} g$

  2. $1.26 \times 10^{-4}g$

  3. $ 3.15 \times 10^{-5}g$

  4. $ 6.3 \times 10^{-5}g$

Show answer
Correct Option: D

State, whether the following statements are True or False:
Aniline forms phenol when treated with nitrous acid.

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

  1. True

  2. False

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Correct Option: B

Which of the following amines form unstable diazonium salt?

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

  1. ${ C } _{ 6 }{ H } _{ 5 }{ NH } _{ 2 }$

  2. $\left( { C } _{ 2 }{ H } _{ 5 } \right) _{ 2 }NH$

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

  4. ${ CH } _{ 3 }{ NHC } _{ 2 }{ H } _{ 5 }$

Show answer
Correct Option: B,C,D
Explanation:

Only primary aromatic amines form stable arene diazonium salts.
The reaction is as follows:

$C _{6}H _{5}NH _{2} + NaNO _{2} + HCl (0-5^{\circ}C) \rightarrow PhN _{2}^{+}Cl^{-}$

Remain forms the unstable diazonium salt.
So, the correct options are $B$, $C$, $D$

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.
$\underset {aniline} {{ C } _{ 6 }{ H } _{ 5 }{ NH } _{ 2 }}\xrightarrow [ { NaNO } _{ 2 } ]{ HCl } \underset {benzene diazonium chloride} {[C _6H _5-N _2^+Cl^-]}$