Solved Examples on Organic Compounds Containing Nitrogen

Question: 1, Compare the basicities of

a)  H₂C = CHCH₂NH₂, CH₃CH₂CH₂NH₂ and HC º CCH₂NH₂, and

b)  C₆H₅CH₂NH₂, cyclohexyl – CH₂NH₂ and p-NO₂C₆H₄CH₂NH₂.

Solution:      

a The significant difference among these three bases is the kind of hybrid orbital used by C^b — the more s character it has, the more electron -  withdrawing (by induction) and base weakening it will be. The HO conditions are H₂C = C^bHCH₂NH₂(sp²), CH₃C^bH₂CH₂NH₂(sp³), and HC º C^bCH₂NH₂(sp). The increasing order of electron – attraction is  propargyl > allyl > propyl >, and the decreasing order of basicity is CH₃CH₂CH₂NH₂> H₂C = CHCH₂NH₂ > HC º CCH₂NH₂

b) The decreasing order is

The C^b is cyclohexyl – CH₂NH₂ uses sp³ HO’s while C^b in the benzylamines uses sp² HO’s. The electron withdrawing p-NO₂ makes the phenyl ring even more electron–withdrawing and base weakening.

Question: 2, A compound X with seven carbon atoms on treatment with Br₂ and KOH gives Y. Y gives carbylamine test and upon diazotisation and coupling with phenol gives azodye. X is

(A)     C₆H₅CONH₂

(B)     CH­₃ – (CH₂)₅ – CONH₂

(C)     CH₃ –C(CH₃)₂- CH_­2 – CH₂ – CONH₂

(D)     O – CH₃ – C₆H₄NH₂

Answer: A

Solution: Since Y gives coupling reaction after diazotisation it suggest that Y can be aniline or benzener ring substituted aniline. Since Y has been obtained from Hoffmann bromamide it means has – CO NH₂ group with benzene ring. Hence it is C₆H₅CONH₂.Hence, the correct option is  (A).

Question: 3, A compound (A) when reacted with PCl₅ and then with NH₃ gave (B), (B) when treated with Br₂ and KOH produced (C). (C) on treatment with NaNO₂ and HCl at 0°C and the boiling with water forms o-cresol. Compound A is

(A) o-toluic acid   

(B) o-chlorotoluene

(C) o-bromo toluene                                             

(D)  m-toluic acid

Answer: A
Solution:The  compound is o-toluic acid, and the reactions involved are

Hence, the correct option is A.

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