CBSE 2023 · Region 2 · Set 1 · Q34 · 5 marks
(I)Give reasons: $\displaystyle 3$ + $\displaystyle 2$(i)Aniline on nitration gives good amount of m-nitroaniline, though $\displaystyle -\mathrm{NH}_{2}$ group is o/p directing in electrophilic substitution reactions.(ii)$\displaystyle \left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}$ is more basic than $\displaystyle \left(\mathrm{CH}_{3}\right)_{3} \mathrm{~N}$ in an aqueous solution.(iii)Ammonolysis of alkyl halides is not a good method to prepare pure primary amines.(II)Write the reaction involved in the following:(i)Carbyl amine test(ii)Gabriel phthalimide synthesis(I)Write the structures of A, B and C in the following reactions: $\displaystyle 3+1+1$(i)(ii)(II)Why aniline does not undergo Friedal-Crafts reaction?(III)Arrange the following in increasing order of their boiling point: $\displaystyle \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}, \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NH}_{2},\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{3} \mathrm{~N}$
(I)
Give reasons: $\displaystyle 3$ + $\displaystyle 2$
(i)
Aniline on nitration gives good amount of m-nitroaniline, though $\displaystyle -\mathrm{NH}_{2}$ group is o/p directing in electrophilic substitution reactions.
(ii)
$\displaystyle \left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}$ is more basic than $\displaystyle \left(\mathrm{CH}_{3}\right)_{3} \mathrm{~N}$ in an aqueous solution.
(iii)
Ammonolysis of alkyl halides is not a good method to prepare pure primary amines.
(II)
Write the reaction involved in the following:
(i)
Carbyl amine test
(ii)
Gabriel phthalimide synthesis
(I)
Write the structures of A, B and C in the following reactions: $\displaystyle 3+1+1$
(i)
(ii)
(II)
Why aniline does not undergo Friedal-Crafts reaction?
(III)
Arrange the following in increasing order of their boiling point: $\displaystyle \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}, \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NH}_{2},\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{3} \mathrm{~N}$
Marking-scheme solution
(a) (I)
(i) Aniline gets protonated and is deactivated / Aniline on protonation forms anilinium ion which is meta-directing.
(ii) Combination of inductive effect and solvation effect.
(iii) Because it forms a mixture of amines that is difficult to separate.
(i) \(\displaystyle \mathrm{R}-\mathrm{NH}_{2}+\mathrm{CHCl}_{3}+\mathrm{NaOH} \longrightarrow \mathrm{RNC}+3 \mathrm{NaCl}+\mathrm{H}_{2} \mathrm{O}\)
AminesChemical Reactions of AminesUnderstandlong_answerhard
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CBSE Class 12 Chemistry past-paper question from the 2023board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.