Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Compounds Containing Nitrogen question

2021 · 16 Mar · Shift 2 · Q6
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Chemistry
  4. /Compounds Containing Nitrogen
  5. /2021 · 16 Mar · Shift 2 · Q6

Compounds Containing Nitrogen question

2021 · 16 Mar · Shift 2 · Q6

JEE MainChemistryCompounds Containing NitrogenMCQ+4 / −1
Which of the following is least basic?
  1. A
    (CH3CO)2N..H{(C{H_3}CO)_2}\mathop N\limits^{..} H(CH3​CO)2​N..​H
  2. B
    (CH3CO)N..HC2H5(C{H_3}CO)\mathop N\limits^{..} H{C_2}{H_5}(CH3​CO)N..​HC2​H5​
  3. C
    (C2H5)3N..{({C_2}{H_5})_3}\mathop N\limits^{..}(C2​H5​)3​N..​
  4. D
    (C2H5)2N..H{({C_2}{H_5})_2}\mathop N\limits^{..} H(C2​H5​)2​N..​H
View written solutionFree

Correct answer: A

  1. Identify the nature of each compound

    We compare the availability of the lone pair on nitrogen, because basicity depends on how easily nitrogen can donate its lone pair.

    • A: (CH3CO)2NH(CH_3CO)_2NH(CH3​CO)2​NH → secondary amide
    • B: (CH3CO)NHC2H5(CH_3CO)NHC_2H_5(CH3​CO)NHC2​H5​ → secondary amide
    • C: (C2H5)3N(C_2H_5)_3N(C2​H5​)3​N → tertiary amine
    • D: (C2H5)2NH(C_2H_5)_2NH(C2​H5​)2​NH → secondary amine

  2. Compare amides vs amines

    In amines (CCC and DDD), the lone pair on nitrogen is localized and available for protonation, so they are relatively more basic.

    In amides (AAA and BBB), the nitrogen lone pair is delocalized by resonance with the carbonyl group:

    R−CO−NH−R′↔R−C(O−)=N+H−R′R-CO-NH-R' \leftrightarrow R-C(O^-)=N^+H-R'R−CO−NH−R′↔R−C(O−)=N+H−R′

    Because of this resonance, the lone pair is much less available, so amides are far less basic than amines.

    Therefore, the least basic must be among A and B.

  3. Compare A and B

    • A: (CH3CO)2NH(CH_3CO)_2NH(CH3​CO)2​NH

      Here nitrogen is attached to two carbonyl groups. Its lone pair is delocalized toward both carbonyl groups, making it very strongly resonance-stabilized and hence least available for protonation.

    • B: (CH3CO)NHC2H5(CH_3CO)NHC_2H_5(CH3​CO)NHC2​H5​

      Here nitrogen is attached to only one carbonyl group and one ethyl group. So resonance withdrawal is less than in A.

    Hence,

    extbasicity:A<B<amines ext{basicity: } A < B < \text{amines}extbasicity:A<B<amines

  4. Check amines C and D

    • (C2H5)2NH(C_2H_5)_2NH(C2​H5​)2​NH and (C2H5)3N(C_2H_5)_3N(C2​H5​)3​N are both much more basic than amides.
    • So neither CCC nor DDD can be the least basic.

  5. Conclusion

    The least basic compound is:

    A\boxed{A}A​
PreviousNext

More from Compounds Containing Nitrogen

  • Ammonolysis of Alkyl halides followed by the treatment with NaOH solution can be used to prepare primary, secondary and tertiary amines. The purpose of NaOH in the reaction is :2021 · MCQ
  • Hoffmann bromomide degradation of benzamide gives product A, which upon heating with CHCl3​ and NaOH gives product B. The structures of A and B are :2021 · MCQ
  • In the above reaction, the structural formula of (A), ''X'' and ''Y'' respectively are : Includes diagram2021 · MCQ
  • Primary, secondary and tertiary amines can be separated using:2021 · MCQ
  • Considering the above reaction, X and Y respectively are : Includes diagram2021 · MCQ
  • An organic compound "A" on treatment with benzene sulphonyl chloride gives compound B. B is soluble in dil. NaOH solution. Compound A is :2021 · MCQ
  • Consider the given reaction, percentage yield of : Includes diagram2021 · MCQ
  • In the reaction of hypobromite with amide, the carbonyl carbon is lost as :2021 · MCQ