Organic Compounds Containing Nitrogen MCQ Questions & Answers in Organic Chemistry | Chemistry

Diazonium salt containing aryl group directly linked to the nitrogen atom is most stable due to resonance stabilisation between the benzene nucleus and $$N$$ - atom. Diazonium ion act as a electrophile.

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TIPS/Formulae : In the formation of cyanohydrin number of carbon atoms in parent chain increases by one.
\[C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}Cl+alc.\,KCN\xrightarrow{{{100}^{\circ }}C}C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}CN+KCl\]

Benzylamine, $${C_6}{H_5}C{H_2} - \ddot N{H_2}$$    is more basic than aniline because benzyl group $$\left( {{C_6}{H_5}C{H_2} - } \right)$$    is electron donating group due to $$ + I$$ - effect So, it is able to increase the electron density of $$N$$ of $$ - N{H_2}$$  group. Thus, due to higher electron density, rate of donation of free pair of electron is increased, i.e. basic character is higher. Phenyl and nitro group are electron withdrawing groups, so they decreases the electron density on $$N$$ of \[-\ddot{N}{{H}_{2}}\]  group. Hence, they are less basic than aniline.

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In aqueous solution, the most basic amine is $${\left( {C{H_3}} \right)_2}NH$$   and hence it is most reactive towards dilute hydrochloric acid.

Only pure aliphatic $${1^ \circ }$$ amines can be prepared by Gabriel synthesis. Aromatic $${1^ \circ }$$ amines such as aniline, toluidines, etc., cannot be prepared by this method because aryl halides $$\left( {{C_6}{H_5}Cl\,\,{\text{or}}\,\,{C_6}{H_5}Br} \right)$$     do not undergo nucleophilic substitution ( i.e., cleavage of $$C-X$$  bond in haloarene is quite difficult ) with potassium phthalimide under ordinary conditions to give $$N$$ - phenyl phthalimide.

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.
\[C{{H}_{3}}-NH-{{C}_{2}}{{H}_{5}}+{{C}_{6}}{{H}_{5}}S{{O}_{2}}Cl\]       \[\to \underset{N\text{-Ethyl-}N\text{-methylbenzene sulphonamide}}{\mathop{C{{H}_{3}}\underset{\begin{smallmatrix} | \\ \,\,\,\,{{C}_{2}}{{H}_{5}} \end{smallmatrix}}{\mathop{-N-}}\,S{{O}_{2}}{{C}_{6}}{{H}_{5}}}}\,\]

Aniline gets coloured on storage due to atmospheric oxidation.