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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 $NR _3$.
Multiple choice distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

Aniline and benzylamine  cannot be distinguished by azo dye test

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Aniline and benzylamine both are aryl systems as only highly activated benzene system gives positive azo dye test below room temperature. Therefore, aniline and benzylamine cannot be distinguished by azo dye test as both give positive azo dye test.

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

A compound $(X)$ with molecular formula $C _3H _9N$ react with $C _6H _5SO _2Cl$ to give a solid which is insoluble in alkali. $(X)$ is:

  1. $CH _3CH _2CH _2NH _2$
  2. $CH _3 - {\underset{CH _3}{\underset{|}{\overset{CH _3}{\overset{|}{N:}}}}}$
  3. $CH _3 - NH - CH _2CH _3$
  4. $CH _3 - {\underset{CH _3}{\underset{|}{CH}}} - NH _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since the compound reacts with benzenesulphonyl chloride to give a product which is insoluble in alkali, it shows there is no $H$ attached to $N$ in the product . Hence, the compound $X$ is a secondary amine.
$CH _3 - NH - C-2H _5 + C _6H _5SO _2Cl \rightarrow \underset{N - Ethyl - N - methylbenzene sulphonamide}{CH _3 - {\underset{C _2H _5}{\underset{|}{N}}} - SO _2C _6H _5}$

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

During preparation of arene diazonium salts, the excess of nitrous acid, if any, is destroyed by adding?

  1. $aq. \, NaOH$
  2. $aq. \, Na _2CO _3$
  3. $aq. \, NH _2CONH _2$
  4. $aq. \, KI$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Urea decomposes $HNO _2$ to give $N _2, \, CO _2 $ and $ H _2O$
$NH _2CONH _2+\, 2HONO \rightarrow 2N _2 \uparrow + \, CO _2 \uparrow +\, 3H _2O$

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

A colourless liquid $A(b.p:184^\circ:C)$ is sparingly soluble in warm water to which it gives feebly alkaline reaction on treating with $NaNO _{2}:and:dil:HCl$ in the cold solution, it yields a solution which reacts with an alkaline solution of $\beta-$napthol to give an orange yellow precipitate. Compound $A$ is :

  1. $C _{6}H _{5}N _{2}Cl$
  2. $C _{6}H _{5}NHNH _{2}$
  3. $n-C _{4}H _{9}NH _{2}$
  4. $C _{6}H _{5}NH _{2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Aniline is the colourless liquid A having boiling point $184 ^oC$.
On treatment with $NaNO _{2}:and:dil:HCl$ at low temperature, it forms benzne diazonum salt.
The diazonium salt reacts with napthol in alkaline medium to form azo dye which is n orange yellow precipitate.