Compounds Containing Nitrogen

Cyanohydrin is formed when carbonyl compound reacts with HCN in the presence of alkali (NaOH).

So, X is alkali i.e. NaOH.

Cyanohydrin on reacting with LiAlH₄ forms amine.

Rhumann’s purple is confirmatory test for the presence of protein. The correct structure of Rhumann’s Purple, the compound formed in the reaction of ninhydrin with proteins is an follows

Primary amine reacts in presence of chloroform gives isonitrile which is toxic in nature which further reacts in presence of HCl/H₃O⁺ to give primary amine and acid.

Hence, A-primary amine, B-isonitrile compound and C-conc. HCl.

In phenyl methanamine, the lone pair on nitrogen of -NH₂ group is localised and does not undergoes resonance.

(B), (C) and (D) are aromatic amines in which lone pair of electrons of N-atoms goes in resonance (+R effect) with the benzene ring. So, Lewis basicity or donation of lone of electrons of these amines will be decreased in comparison to (A).

+ I effects of two -CH₃ groups increases electron density on N atom while lone pair of N atom take part in resonance with the benzene ring and decreases electron density on N atom. Both this effect try to compensate each other.

+ I effects of one -CH₃ groups increases electron density on N atom while lone pair of N atom take part in resonance with the benzene ring and decreases electron density on N atom. Both this effect try to compensate each other.

It has no + I-effect on N-atom to increase electron density on the N atom which was decreased due to lone pair of N atom take part in resonance with the benzene ring. So, A is purely aliphatic 1°-amine. B is aromatic. 3°-amine with more aliphatic nature (for two -CH₃ groups). C is aromatic 2°-amine with less aliphatic nature (for one -CH₃ group).
D is purely aromatic 1°-amine.

Hence basicity order is A > B > C > D.

Nitrating mixture is mixture of conc. HNO₃ and a conc. H₂SO₄.

When aniline is reacted with nitrating mixture ortho, meta and para nitroanilines are obtained.

Aniline being basic in nature, reacts with acids to form anilinium ion which is meta directing.

(a) If KNO₂ (Q)-on reacting with PhCH₂Br(P) gives PhCH₂ONO which on reduction with LiAlH₄ does not give PhCH₂NH₂.

(b) If product R formed is benzylamine not benzene amine. KCN reacts with PhCH₂ Br to give PhCH₂CN which does not have foul smelling.

(c) If AgNO₂ (Q) reacts with PhCH₂ Br to give PhCH₂NO₂ which on reduciton give PhCH₂NH₂ (Phenyl methanamine or benzyl amine).

(d) If amide reacts with LiAlH 4 (W) to give amine. PhCH₂ Br reacts with AgCN to give PhCH₂NO₂ .

PhSNa replaces F from o- and p-dinitro- fluorobenzene via nucleophilic aromatic substitution.

PhSNa replaces Cl from compound D via nucleophilic bimolecular substitution reaction.

In case of compound B and C, nucleophilic substitution is not possible neither by S_NAr or S_N2 . because, the electron withdrawing group is present at meta-position and halogen is attached to sp²-carbon.

Due to presence of electron withdrawing nitro group, delocalisation of lone pair of electron is improved. This effect observed in para and ortho position.

In ortho position, very close inductive effect of nitro group is also observed. Hence, o-nitroaniline is less basic than p-nitroaniline. In m-nitroaniline, only inductive effect is present.

Order of basicity is as follows:

aniline > m-nitroaniline > p-nitroaniline > o-nitroaniline.

$25 \mathrm{~mL}$ of $1 \mathrm{M} \mathrm{~H}_2 \mathrm{SO}_4$ corresponds to $25 \mathrm{~m} \mathrm{~mol}$.

It will neutralise $50 \mathrm{~mol}$ of $\mathrm{NH}_3$.

weight of $\mathrm{N}=\frac{14 \times 50}{1000} \mathrm{~g}=0.70 \mathrm{~g}$

Thus $\mathrm{l} \mathrm{g}$ of sample of organic compound contains $0.70 \mathrm{~g}$ of nitrogen.

$\%$ of nitrogen in organic sample is $\frac{0.70}{1} \times 100=70 \%$