Question Set B

Organic Nitrogen Compounds

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Questions:

Multiple Choice Question

8 x 1 = 8

Secondary nitro alkanes react with nitrous acid to form _______.

(a)

red solution

(b)

blue solution

(c)

green solution

(d)

yellow solution

C₆H₅NO₂ \(\overset { Fe/Hel }{ \longrightarrow } A\overset { { NaNO }_{ 2 }/HCl }{ \underset { 273K }{ \longrightarrow } } B\overset { { H }_{ 2 }O }{ \underset { 283 }{ \longrightarrow } } C \) C' is _______.

(a)

C₆H₅- OH

(b)

C₆H₅- CH₂OH

(c)

C₆H₅- COH

(d)

C₆H₅NH₂

When aniline reacts with acetic anhydride the product formed is_______.

(a)

o – aminoacetophenone

(b)

m-aminoacetophenone

(c)

p – aminoacetophenone

(d)

acetanilide

The product formed by the reaction an aldehyde with a primary amine ________.

(a)

carboxylic acid

(b)

aromatic acid

(c)

schiff ’s base

(d)

ketone

Aniline + benzoylchloride \(\overset { NaOH }{ \longrightarrow } \)C₆H₅ - NH - COC₆ H₅ this reaction is known as ______.

(a)

Friedel – crafts reaction

(b)

HVZ reaction

(c)

Schotten – Baumann reaction

(d)

none of these

CH₃CH₂ Br \(\overset { aqNaOH }{ \underset { \Delta }{ \longrightarrow } } A\overset { { KMnO }_{ 4 }{ /H }^{ + } }{ \underset { \Delta }{ \longrightarrow } } B\overset { { NH }_{ 3 } }{ \underset { \Delta }{ \longrightarrow } } C\overset { { Br }_{ 2 }/NaOH }{ \longrightarrow } D\) D' is________.

(a)

bromomethane

(b)

α - bromo sodium acetate

(c)

methanamine

(d)

acetamide

The method by which aniline cannot be prepared is _________.

(a)

degradation of benzamide with Br₂ / NaOH

(b)

potassium salt of phthalimide treated with chlorobenzene followed by hydrolysis with aqueous NaOH solution.

(c)

reduction of Nitrobenzene with LiAlH₄

(d)

reduction of nitrobenzene by Sn / HCl

Which of the following reagent can be used to convert nitrobenzene to aniline.

(a)

Sn / HCl

(b)

ZnHg / NaOH

(c)

Zn/NH₄Cl

(d)

All of these

Generic 2

1 x 2 = 2

Write down the possible isomers of the C₄H₉NO₂ give their IUPAC names.

Generic 5

4 x 5 = 20

10.

Identify A to E in the following sequence of reactions

\(\overset { {CH_3} {CL} }{ \underset { {AlCl}_3 }{ \longrightarrow } }\) A \(\overset { {HNO_3}/ {H_2So_4} }{ \underset { {} }{ \longrightarrow } }\) B \(\overset { {Sn} /{HCL} }{ \underset {{} }{ \longrightarrow } }\) (C) \(\overset { {NaNo_2}/ {HCL} }{ \underset { {O^o}C }{ \longrightarrow } }\) D \(\overset { {CuCN} }{ \underset { {}}{ \longrightarrow } }\) E

11.

How will you distinguish between primary secondary and tertiary alphatic amines.

12.

Write short notes on the following
i. Hofmann’s bromide reaction
ii. Ammonolysis
iii. Gabriel phthalimide synthesis
iv. Schotten – Baumann reaction
v. Carbylamine reaction
vi. Mustard oil reaction
vii. Coupling reaction
viii. Diazotisation
ix. Gomberg reaction

13.

Identify compounds A, B and C in the following sequence of reactions.
i) \({ C }_{ 6 }{ H }_{ 5 }NO_{ 2 }\overset { Fe/HCL }{ \longrightarrow } A\overset { HN{ O }_{ 2 } }{ \underset { 273K }{ \longrightarrow } } B\overset { { C }_{ 6 }{ H }_{ 5 }OH }{ \longrightarrow } C\)
ii) \({ C }_{ 6 }{ H }_{ 5 }N_{ 2 }cl\overset { CuCN }{ \longrightarrow } A\overset { H_{ 2 }O/H^{ + } }{ \longrightarrow } B\overset { NH_3 }{ \longrightarrow } C\)
iii) \({ C }{ H }_{ 3 }{ C }{ H }_{ 2 }I\overset { NaCN}{ \longrightarrow } A\overset {OH^-}{ \underset {Partial hydrolysis}{ \longrightarrow } } B\overset {NaOH+Br_2 }{ \longrightarrow } C\)
iv) \({ C }{ H }_{ 3 }NH_{ 2 }\overset { CH_3 Br }{ \longrightarrow } A\overset { CH_{ 3 }COCl}{ \longrightarrow } B\overset { B_2H_6 }{ \longrightarrow } C\)
v) \({ C }_{ 6 }{ H }_{ 5 }NH_{ 2 }\overset { (CH_{ 3 }CO)_{ 2 }O }{ \underset { Pyridine }{ \longrightarrow } } A\overset { HNO_{ 3 } }{ \underset { H_{ 2 }SO_{ 4 },288K }{ \longrightarrow } } B\overset { { H }_{ 2 }O/{ H }^{ + } }{ \longrightarrow C } \)
vi)

vii) \({ C }{ H }_{ 3 }CN_{ 2 }NC\overset { HgO }{ \longrightarrow } A\overset { H_{ 2 }O }{ \longrightarrow } B\overset { i) NaN{ O }_{ 2 }/HCL }{ \underset { ii){ H }_{ 2 }O }{ \longrightarrow } } \)

Generic 3

2 x 3 = 6

14.

Identify A,B,and C
CH₃- NO₂ \(\overset { { L }_{ 1 }{AlH }_{ 4 } }{ \underset { {} }{ \longrightarrow } }\) A \(\overset { { 2CH_3 }{Ch_2Br } }{ \underset { {} }{ \longrightarrow } }\) B \(\overset { {H}_{ 2 }{SO}_{ 4 } }{ \underset { {} }{ \longrightarrow } } \) C

15.

How will you convert diethylamine into
i) N, N – diethylacetamide
ii) N – nitrosodiethylamine

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Answers Key:

Multiple Choice Question

8 x 1 = 8

(b)
blue solution

(a)
C₆H₅- OH

(d)
acetanilide

(b)
potassium salt of phthalimide treated with chlorobenzene followed by hydrolysis with aqueous NaOH solution.

(a)
Sn / HCl

Generic 2

1 x 2 = 2

Isomerism	Structural formula of isomers
Chain isomerism: They differ in the length of carbon chain.
Position isomerism: They differ in the position of nitro group.
Functional isomerism: Nitroalkanes exhibit functional isomerism with alkylnitrites	\( \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2}-\mathrm{NO}_{2} \text { and } \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2}-\mathrm{O}-\mathrm{N}=\mathrm{O}\\ \quad 1 - nitrobutane \quad \quad \quad \quad \quad \quad \quad butyl \ nitrite\)

Generic 5

4 x 5 = 20

10.

11.

S.No	Reagents or Reaction	Primary amine RNH₂	Secondary amine R₂NH	Tertiary amine R₃N
1.	Carbylamine reaction or with CHCl₃/KOH	Carbylamine is formed (unpleasant smell)	-	-
2.	Mustard oil reaction or CS₂/HgCl₂ (Hoffmann's mustard oil test)	Alkyl isothiocyanate is formed (Mustard oil odour)	-	-
3.	HNO₂ (or) NaNO₂/ HCl	Alcohol is formed +H₂	Yellow oily nitrosoamine is formed, insoluble in water. (Liberman's Test)	Forms nitrite in cold, soluble in water.
4.	CH₃COCl	N-acetyl derivative is formed	N,N- diacetyl derivative is formed	-
5.	Diethyl oxalate Hoffmann's method	Solid oxamide is formed	Liquid oxamic ester is formed	-
6.	Benzene sulphonyl chloride in presence of excess. KOH (Hinsberg's reaction)	N- alkyl benzene sulphonamide is formed (soluble)	N, N - dialkyl benzene sulphonamide is formed (Insoluble).	-
7.	With RX	1 mol → 2^o amine 2 mol → 3^o amine 3 mol → Quarternary salt	1 mol → 3^o amine 2 mol → Quarternary salt	1 mol → Quarternary salt

12.

Hoffmann's bromide reaction:
When Amides are treated with bromine in the presence of aqueous or ethanolic solution of KOH, primary amines with one carbon atom less than the parent amides are obtained.
\(\underset { \quad \quad \quad amide\\ R=Alkyl(or)Aryl }{ R-\overset { \underset { || }{ O } }{ C } -{ NH }_{ 2 } } \overset { { Br }_{ 2 }/KOH }{ \longrightarrow } \underset { Primary\quad amine }{ R-{ NH }_{ 2 }+{ K }_{ 2 }{ CO }_{ 3 } } +KBr+{ H }_{ 2 }O\)
(ii) Hoffmann's ammonolysis:
When Alkyl halides (or) benzylhalides are heated with alcoholic ammonia in a sealed tube, mixtures of 1°, 2° and 3° amines and quaternary ammonium salts are obtained.
\( { CH }_{ 3 }-Br\overset { \ddot { N } { H }_{ 3 } }{ \underset { \Delta }{ \longrightarrow } } \underset { { 1 }^{ 0 }-amine }{ { CH }_{ 3 }-\ddot { N } { H }_{ 2 } } \overset { { CH }_{ 3 }-Br }{ \longrightarrow } \underset { { 3 }^{ o }-amine }{ \left( { CH }_{ 3 } \right) _{ 2 }\ddot { N } H } \overset { { CH }_{ 3 }Br }{ \longrightarrow } \underset { 3^{ o }-amine }{ \left( { { CH }_{ 3 } } \right) _{ 3 }\ddot { N } } \overset { CH_{ 3 }Br }{ \longrightarrow } \underset { Quartenary \ ammonium\ bromide }{ \left( { CH }_{ 3 } \right) _{ 4 }\overset { + }{ N } { Br }^{ - } } \)
This is a nucleophilic substitution, the halide ion of alkyl halide is substituted by the -NH₂ group. The product primary amine so formed can also has a tendency to act as a nucleophile and hence if excess alkyl halide is taken, further nucleophilic substitution takes place leading to the formation of quarternary ammonium salt. However, if the process is carried out with excess ammonia, primary amine is obtained as the major product. The order of reactivity of alkylhalides with amines
RI > RBr > RCl
(iii) Gabriel phthalimide synthesis:
Gabriel synthesis is used for the preparation of Aliphatic primary amines. Phthalimide on treatment with ethanolic KOH forms potassium salt of phthalimide which on heating with alkyl halide followed by alkaline hydrolysis gives primary amine. Aniline cannot be prepared by this method because the arylhalides do not undergo nucleophilic substitution with the anion formed by phthalimide.

(iv) Schotten - Baumann reaction :
Aniline reacts with benzoylchloride (C₆H₅COCI) in the presence of NaOH to give N - phenyl benzamide. This reaction is known as Schotten - Baumann reaction. The acylation and benzoylation are nucleophilic substitutions.
\(\underset { Aniline }{ { C }_{ 6 }{ H }_{ 5 }-{ NH }_{ 2 } } +\underset { Benzoyl\quad chloride }{ { C }_{ 6 }{ H }_{ 5 }-\overset { \underset { || }{ O } }{ C } -Cl } \overset { Pyridine }{ \longrightarrow } \underset { N-phenyl\quad benzamide }{ { C }_{ 6 }{ H }_{ 5 }-NH-\overset { \underset { || }{ O } }{ C } -{ C }_{ 6 }{ H }_{ 5 } } +HCl\)
(v) Carbylamine reaction :
Aliphatic (or) aromatic primary amines react with: chloroform and alcoholic KOH to give isocyanides (carbylamines), which has an unpleasant smell. This reaction is known as carbylamines test. This test used to identify the primary amines.
\(\underset { Ethylamine }{ { C }_{ 2 }{ H }_{ 5 }-{ NH }_{ 2 } } +\underset { Chloroform }{ { CHCl }_{ 3 }+3KOH } \longrightarrow \underset { Ethylisocyanide }{ { C }_{ 2 }{ H }_{ 5 }-NC } +3KCl+3{ H }_{ 2 }O\)
(vi) Mustard oil reaction:
(a) When primary amines are treated with carbon disulphide (CS₂), N - alkyldithio carbonic acid is formed which on subsequent treatment with HgCI₂, gives an alkyl isothiocyanate.

(b) When aniline is treated with carbon disulphide, or heated together, S-diphenylthio urea is formed, which on boiling with strong HCI, phenyl isothiocyanate (phenyl mustard oil), is formed.

These reactions are known as Hofmann - Mustard oil reaction. This test is used to identify the primary amines.
(vii) Coupling reactions (or) p-hydroxyazobenzene, p-aminoazobenzene, 2-phenyl azo-4-methyl phenol:
Benzene diazonium chloride reacts with electron rich aromatic compounds like phenol, aniline to form brightly coloured azo compounds. Coupling generally occurs at the para position. If para position is occupied then coupling occurs at the ortho position. Coupling tendency is enhanced if an electron donating group is present at the para - position to -N₂CI- group. This is an electrophilic substitution.

Aryl fluorides and iodides cannot be prepared by direct halogenation and the cyano group cannot be introduced by nucleophilic substitution of chlorine in chlorobenzene. For introducing such a halide group. cyano group -OH, NO₂, etc.. benzenediazonium chloride is a very good intermediate Diazo compounds obtained from the coupling reactions of diazonium salts are coloured and are used as dyes.
(viii) Diazotisation :
Aniline reacts with nitrous acid at low temperature (273 - 278 K) to give benzene. Diazonium chloride which is stable for a short time and slowly decomposes even at low temperatures.This reaction is known as diazotization

(ix) Gomberg reaction :
Benzene diazonium chloride reacts with benzene in the presence of sodium hydroxide to give biphenyl. This reaction in known as the Gomberg reaction