Learn Organic Compounds Containing Nitrogen MCQ questions & answers in Organic Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
1.
Cyclohexylamine is stronger base than aniline because
A
in aniline electron pair is involved in conjugation
B
in cyclohexylamine electron pair is involved in conjugation
C
in aniline $$ - N{H_2}$$ group is protonated
D
in cyclohexylamine nitrogen has a negative charge
Answer :
in aniline electron pair is involved in conjugation
No explanation is given for this question. Let's discuss the answer together.
2.
The order of basicity of amines in gaseous state is :
A
\[{{1}^{\circ }}>{{2}^{\circ }}>{{3}^{\circ }}>N{{H}_{3}}\]
B
\[{{3}^{\circ }}>{{2}^{\circ }}>N{{H}_{3}}>{{1}^{\circ }}\]
C
\[{{3}^{\circ }}>{{2}^{\circ }}>{{1}^{\circ }}>N{{H}_{3}}\]
D
\[N{{H}_{3}}>{{1}^{\circ }}>{{2}^{\circ }}>{{3}^{\circ }}\]
The correct order of relative basicity of amines in the gas phase is \[{{3}^{\circ }}>{{2}^{\circ }}>{{1}^{\circ }}>N{{H}_{3}}\]
The alkyl group releases electron and thus, tends to disperse the positive charge of the alkyl ammonium $$ion$$ and therefore stabilises it. Since, \[NH_{4}^{+}\] ( from \[N{{H}_{3}}\] ) has no such alkyl group, it is not stabilised to such an extent as alkylammonium $$ion.$$
3.
Indicate which nitrogen compound amongst the following would undergo Hofmann reaction?
A
$$RCONHC{H_3}$$
B
$$RCOON{H_4}$$
C
$$RCON{H_2}$$
D
$$RCONHOH$$
Answer :
$$RCON{H_2}$$
When amides react with bromine in the presence of caustic alkali to form a primary amine carrying one carbon atom less than the parent amide, then the reaction is known as Hofmann bromamide reaction.
$$RCON{H_2} + B{r_2} + 4KOH$$ \[\xrightarrow{\text{Heat}}RN{{H}_{2}}+{{K}_{2}}C{{O}_{3}}\] $$ + 2KBr + 2{H_2}O$$
4.
Coupling of diazonium salts of following takes place in the order
A
IV < II < III < I
B
IV > III < II < I
C
II < IV < I < III
D
I < II < III < IV
Answer :
IV < II < III < I
No explanation is given for this question. Let's discuss the answer together.
5.
In the Hofmann bromamide degradation reaction, the number of moles of $$NaOH$$ and $$B{r_2}$$ used per mole of amine produced are:
A
Two moles of $$NaOH$$ and two moles of $$B{r_2}$$
B
Four moles of $$NaOH$$ and one mole of $$B{r_2}$$
C
One mole of $$NaOH$$ and one mole of $$B{r_2}$$
D
Four moles of $$NaOH$$ and two moles of $$B{r_2}$$
Answer :
Four moles of $$NaOH$$ and one mole of $$B{r_2}$$
4 moles of $$NaOH$$ and one mole of $$B{r_2}$$ is required during production of one mole of amine during Hoffmann's
bromamide degradation reaction.
\[R\overset{\begin{smallmatrix}
O \\
\parallel
\end{smallmatrix}}{\mathop{-C-}}\,N{{H}_{2}}+B{{r}_{2}}+4NaOH\] \[\to R-N{{H}_{2}}+{{K}_{2}}C{{O}_{3}}+2NaBr+2{{H}_{2}}O\]
6. $$ + C{H_3}MgBr \to P$$
Product $$P$$ in the above reaction is
A
B
C
D
Answer :
7.
In the chemical reactions,
the compounds $$'A'$$ and $$'B'$$ respectively are
A
nitrobenzene and fluorobenzene
B
phenol and benzene
C
benzene diazonium chloride and fluorobenzene
D
nitrobenzene and chlorobenzene
Answer :
benzene diazonium chloride and fluorobenzene
Primary aromatic amines react with nitrous acid to yield arene diazonium salts.
\[\underset{{{1}^{\circ }}\,\text{Aromatic amine}}{\mathop{ArN{{H}_{2}}+NaN{{O}_{2}}}}\,+2HX\xrightarrow{cold}\underset{\text{Arenediazonium salt}}{\mathop{Ar-N={{N}^{+}}{{X}^{-}}}}\,+NaX+2{{H}_{2}}O\]
The diazonium group can be replaced by fluorine by treating the diazonium salt with fluoroboric acid $$\left( {HB{F_4}} \right).$$ The precipitated diazonium fluoroborate is isolated, dried and heated until decomposition occurs to yield the aryl fluoride. This reaction is known as Balz - Schiemann reaction.
\[Ar-{{N}_{2}}^{+}{{X}^{-}}\xrightarrow{HB{{F}_{4}}}Ar-{{N}_{2}}^{+}B{{F}_{4}}^{-}\downarrow \xrightarrow{heat}Ar-F+B{{F}_{3}}+{{N}_{2}}\]
8.
Electrolytic reduction of nitrobenzene in weakly acidic medium gives
A
aniline
B
nitrosobenzene
C
$$N$$ - phenyl hydroxylamine
D
$$p$$ - hydroxyaniline
Answer :
aniline
9.
Which of the following does not give $$N–$$ ethyl cyclopentylamine as major product ?
A
B
C
D
Answer :
10.
The formation of cyanohydrin from a ketone is an example of :
A
Electrophilic addition
B
Nucleophilic addition
C
Nucleophilic substitution
D
Electrophilic substiution
Answer :
Nucleophilic addition
TIPS/Formulae : The addition is initiated by the attack of $$C{N^ - }$$ group which is a nucleophile.