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.
251.
The correct order of decreasing basic character of the three aliphatic primary amines is
A
$${\text{I > II > III}}$$
B
$${\text{III > II > I}}$$
C
$${\text{I}} > {\text{II}} \approx {\text{III}}$$
D
$${\text{I}} = {\text{II}} \equiv {\text{III}}$$
Answer :
$${\text{I > II > III}}$$
Note the point of difference in the given compounds which here lies at $$\beta $$ - carbon. In I, II, III, the $$\beta $$ - carbon atoms are $$s{p^3},s{p^2}$$ and $$sp$$ hybridised respectively which in turn cause the difference in their $$s$$ - character. We know that more is the $$s$$ character of an atom, greater will be its electron-withdrawing nature. Thus $$sp$$ ( $$50\% \,\,s$$ character ) hybridised carbon is most electron-withdrawing, while $$s{p^3}$$ ( $$25\% $$ $$s$$ - character ) is least electron-withdrawing. Further, we know that presence of an electron-withdrawing group decreases basicity of an amine. Thus
252.
$${C_3}{H_9}N$$ cannot represent
A
$${1^ \circ }$$ amine
B
$${{\text{2}}^ \circ }$$ amine
C
$${3^ \circ }$$ amine
D
quaternary ammonium salt
Answer :
quaternary ammonium salt
Quaternary ammonium salt, as it carries a positive charge over nitrogen. e.g., $${\left( {C{H_3}} \right)_4}\mathop N\limits^ + C{l^ - }$$
253.
The major product of the following reaction is
A
B
C
D
Answer :
254.
Which of the following compounds will not undergo azo coupling reaction with benzene diazonium chloride?
A
Aniline
B
Phenol
C
Anisole
D
Nitrobenzene
Answer :
Nitrobenzene
Diazonium cation is a weak electrophile and hence reacts with electron rich compounds containing electron donating groups such as $$ - OH, - N{H_2}$$ and $$ - OC{H_3}$$ groups and not with compounds containing electron withdrawing groups such as $$ - N{O_2},$$ etc.
255.
When Benzenesulfonic acid and $$p - $$ nitrophenol are treated with $$NaHC{O_3},$$ the gases released respectively are
A
$$S{O_2},NO$$
B
$$S{O_2},N{O_2}$$
C
$$C{O_2},C{O_2}$$
D
$$S{O_2},C{O_2}$$
Answer :
$$C{O_2},C{O_2}$$
When benzene sulphuric acid and $$p$$ - nitrophenol are treated with $$NaHC{O_3},$$ the gases released, respectively are $$C{O_2},C{O_2}.$$
The balanced chemical equation for the reaction of benzene sulphonic acid with sodium bicarbonate is as shown below.
$$PhS{O_3}H + NaHC{O_3} \to $$ $$PhS{O_3}Na + C{O_2} + {H_2}O$$
The balanced chemical equation for the reaction of $$p$$ - nitro phenol with sodium bicarbonate is as show below.
$$p - {O_2}N - {C_6}{H_4} - OH + NaHC{O_3} \to $$ $$p - N{O_2} - {C_6}{H_4} - ONa + C{O_2} + {H_2}O$$
256.
Consider the reaction
$$C{H_3}C{H_2}C{H_2}Br + NaCN \to $$ $$C{H_3}C{H_2}C{H_2}CN + NaBr$$
This reaction will be the fastest in
A
ethanol
B
methanol
C
$$N,N'$$ - dimethylformamide $$(DMF)$$
D
water
Answer :
$$N,N'$$ - dimethylformamide $$(DMF)$$
The given reaction follows $${S_N}2$$ mechanism and $${S_N}2$$ reactions are favoured in polar aprotic medium like $$DMSO,DMF...$$ etc.
\[C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}Br+NaCN\xrightarrow{DMF}C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}CN+NaBr\]
So, the correct option is (C).
257.
In the reaction shown below, the major product$$(s)$$ formed is/are \[\xrightarrow[C{{H}_{2}}C{{l}_{2}}]{\text{acetic anhydride}}\text{Product}\left( S \right)\]
A
B
C
D
Answer :
\[-\ddot{N}{{H}_{2}}\] group is acetylated by acetic anhydride in methylene chloride (solvent).
Note that \[-CON{{H}_{2}}\] group does not undergo acetylation because here lone pair of electrons is delocalised.
258.
The major product of the following reaction is
A
B
C
D
Answer :
259.
Primary and secondary amines are distinguished by
A
$$\frac{{B{r_2}}}{{KOH}}$$
B
$$HClO$$
C
$$HN{O_2}$$
D
$$N{H_3}$$
Answer :
$$HN{O_2}$$
No explanation is given for this question. Let's discuss the answer together.
260.
A compound $$A$$ has a molecular formula $${C_7}{H_7}NO.$$ On treatment with $$B{r_2}$$ and $$KOH,$$ $$A$$ gives an amine $$B$$ which gives carbylamine test. $$B$$ upon diazotization and coupling with phenol gives an azo dye. $$A$$ can be
A
$${C_6}{H_5}CONHCOC{H_3}$$
B
$${C_6}{H_5}CON{H_2}$$
C
$${C_6}{H_5}N{O_2}$$
D
$$o{\text{ - ,}}\,m{\text{ - }}\,{\text{or}}\,\,p{\text{ - }}{C_6}{H_4}\left( {N{H_2}} \right)CHO$$