Tag: distinction between pairs of amines

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Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

Aniline and N-methylaniline can be distinguished by using the:
(A) Hoffman Mustard oil reaction
(B)  Hinsberg reagent
(C)  Carbylamine test
(D)   Mulliken Test

  1. B and C

  2. C only

  3. A, B and C

  4. A, B, C and D
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Aniline is a primary amine, while N-methylaniline is a secondary amine. The Carbylamine test (C) is specific to primary amines, and the Hinsberg reagent (B) reacts differently with primary and secondary amines, making both useful for distinction.

Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

Nitration of acetanilide followed by hydrolysis gives

  1. Ortho nitro aniline

  2. Para nitroaniline

  3. Ortho and para nitroaniline

  4. Ortho nitro anilinium ion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Acetanilide is nitrated to form p-nitroacetanilide because the acetamido group is bulky, directing substitution to the para position. Subsequent hydrolysis of the amide group yields para-nitroaniline.

Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

The reaction between primary amine, chloroform and few drops of alcoholic KOH is known as: 

  1. Hofmann's reaction

  2. Reimer-Tiemann's reaction

  3. Carbylamine reaction

  4. Kolbe's reaction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Carbylamine reaction:
$C{ H } _{ 3 }C{ H } _{ 2 }N{ H } _{ 2 }+CH{ Cl } _{ 3 }+3KOH\longrightarrow C{ H } _{ 3 }C{ H } _{ 2 }NC+3KCl+3{ H } _{ 2 }O$
It forms isocyanide.
Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

Aniline and diphenylamine may be distinguished by:

  1. lassaignes test

  2. schiffs test

  3. carbyl amine reaction

  4. solubility test
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Aniline and diphenylamine may be distinguished by carbylamine reaction.
Aniline is a primary amine and diphenylamine is a secondary amine.
carbylamine reaction is given by primary amines. It is not given by secondary or tertiary amines.
In Hoffmann's carbylamine test (also known as Isocyanide test), aliphatic or aromatic primary amine is heated with chloroform  in presence of alcoholic potassium hydroxide to give foul smelling alkyl/aryl  isocyanide or carbylamine.
$\underset {} {C _6H _5-NH _2} + CHCl _3  + 3KOH  \xrightarrow {heat} C _6H _5-NC  + 3KCl + 3H _2O$

Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

Which of the following is an example of azo dye?

  1. Orange-1

  2. Malachite green

  3. Indigo

  4. Martius yellow
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Azo dye are a large class of synthetic organic dyes, that contain nitrogen as the azo group or $−N=N−$ as a part of their molecular structures. Orange-1 is an example of azo dye.

Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

Primary, secondary, tertiary amines can be separated by the following except: 

  1. Fractional distillation

  2. Fractional method using diethyl oxalate
  3. Hinsberg's method using $\displaystyle { C } _{ 6 }{ H } _{ 5 }{ SO } _{ 2 }Cl$

  4. Selective crystallisation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Separation of $1^o,\, 2^o$ and $3^o$ amines:

$1^o,\, 2^o$ and $3^o$ amines + $R _4NX \xrightarrow{distillation}$ Mixture of $1^o,\, 2^o,\, 3^o$ amine
Mixture  of $1^o,\, 2^o,\, 3^o$ amine can be separated by following methods.
(i) Fractional distillation: The mixture of amines may be fractional distillation because their boiling points are quite different. It is used in industry.

(ii) Hinsberg method: In this method mixture of amines is seperated by using benzene sulphonyl chloride (Hinsberg's reagent).
$C _6H _5SO _2Cl+1^o\,amine \to Product \xrightarrow{KOH} dissolve$
$C _6H _5SO _2Cl+2^o\,amine \to Product \xrightarrow{KOH} insoluble$
$3^o$ amine does not react with benzene sulphonyl chloride.

(iii) Hofman method: In this method mixture of amines is separated by using ethyl oxalate.
$1^o$ amine + ethyl oxalate $\to$ solid product
$2^o$ amine + ethyl oxalate $\to$ liquid product
$3^o$ amine + ethyl oxalate $\to$ No reaction

Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

In order to distinguish between $\displaystyle C _{2}H _{5}NH _{2}$ and $\displaystyle C _{6}H _{5}NH _{2}$, which of the following reagents is useful? 

  1. Hinsberg reagent
  2. $\beta$-Naphthol

  3. Benzene diazonium chloride

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ethylamine (aliphatic) and aniline (aromatic) can be distinguished using the azo dye test. Aniline reacts with nitrous acid to form a diazonium salt, which couples with beta-naphthol to form an orange-red dye, whereas ethylamine does not form a stable diazonium salt under these conditions.

Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

p-chloroaniline and anilinium hydrochloride can be distinguished by :

  1. $Sandmeyer $ $reaction$
  2. $\displaystyle NaHCO _{3}$
  3. $\displaystyle AgNO _{3}$
  4. $carbylamines$ $ test$
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation

p-chloroaniline and anilinium hydrochloride can be distinguished by by using $AgNO _3$ and $NaHCO _3$, With $AgNO _3 $ anilinium hydrochloride gives white precipitate of $AgCl$. 


$NaHCO _3$ is a weak acid  which solublize anilinium hydrochloride and $CO _2$ gas liberates but  p-chloroaniline do not react with them.

Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

Mixture of $1^0, 2^0 $ and $3^0$ amines can be separated by :

  1. Hinsberg's method

  2. Hofmann's isocyanide test

  3. Fractional distillation
  4. $NaNO _2/ HCl$
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation
All the given methods can be used for the separation of amines.

(A) Hinsberg reaction is a chemical test for the detection of amines. A primary amine will form a soluble sulfonamide salt which precipitates after addition of diluted hydrochloric acid. A secondary amine in the same reaction will directly form an insoluble sulfonamide. A tertiary amine will not react with the sulfonamide but is insoluble. After adding dilute acid this insoluble amine is converted to a soluble ammonium salt. 

(B) In Hofmann's isocyanide test the mixture of three amines is treated with diethyl oxalate. The primary amine forms a solid oxamide, a secondary amine gives a liquid oxamic ester while tertiary amine does not react.

(C) In fractional distillation primary amine is recovered when solid oxamide is heated with caustic potash solution and collected as distillate on distilling the reaction mixture. The liquid is subjected to fractional distillation when tertiary amine distils over. The remaining liquid is distilled with KOH to recover secondary amine.

(D) Nitrosation of Amines can also be used for separation as primary amine with $NaNO _2 + HCl$ forms $RN _2$, secondary amine forms $R _2N _2O$ and tertiary amine forms $R _3NO$ which decomposes into $NR _3$.