One amine is more basic than ammonia and the other is less basic

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 Multiple Choice QuestionsMultiple Choice Questions

561.

Mark the correct statement.

  • Methylamine is slightly acidic

  • Methylamine is less basic than NH3

  • Methylamine is stronger base than NH3

  • Methylamine forms salt with alkalies


562.

Which among the following represents an amide?


563.

In the carbylamine reaction, R-X is converted to R-Y via the intermediate Z. R-X, R-Y and Z, respectively, are

  • RNH2, RNC, Carbene

  • RNH2, RNC, nitrene

  • RNC, RNH2, carbene

  • ROH, RNC, nitrene


564.

Which one of the following is the strongest base ?

  • 2,4,6-trinitroaniline

  • 2,4,6-trinitro-N,N-dimethyl aniline

  • N, N-dimethyl aniline

  • Anline


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565.

Hinsberg's reagent is

  • benzene sulphonyl chloride

  • benzene sulphonic acid

  • phenyl isocyanide

  • benzene sulphonamide


566.

The given reaction is called as

  • Schmidt rearrangement

  • Curtius rearrangement

  • Hofmann rearrangement

  • Lossen rearrangement


567.

Correct basicity of the following compounds are

I. Aniline

II. Pyridine

III. Pyrrole

IV. Guanidine

  • I >II >III >IV

  • III >I >II >IV

  • IV >II >I >III

  • II >IV>III >I


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568.

One amine is more basic than ammonia and the other is less basic than ammonia. The two amines are respectively

  • N-methyl ethanamine and N, N-dimethyl ethanamine

  • aniline and N-methyl aniline

  • N-methyl aniline and aniline

  • N, N-dimethyl aniline and benzenamine


A.

N-methyl ethanamine and N, N-dimethyl ethanamine

Three classes of amine, i.e. 1°, 2° and 3° amine are stronger bases than ammonia. It is due to the reason that alkyl groups are electron donating groups. As a result, the electron density on the nitrogen atom increases and thus, they can donate the lone pair of electrons more easily than ammonia. Thus, the basicity of amines should decrease in the order 3° amine > 2° amine > 1° amine > ammonia.

Aromatic amines are far less basic than ammonia. This is because due to resonance in aniline, the lone pair of electrons on the nitrogen atom gets delocalised over the benzene ring and thus is less easily available for protonation.

When the hydrogen atom of the amino group in aniline are replaced by electron donating alkyl groups, the basicity of resultant arylamines increases. e.g., N-methylaniline is a stronger base than aniline and N, N-dimethyl aniline is even stronger than N-methylaniline. However, they are not stronger bases than ammonia. Thus, the basicity of N-substituted anilines relative to aniline follows the sequence

NH3C6H5-N(CH3)2N, N- dimethyl aniline > C6H5-N(H)(CH3)N-methylaniline > C6H5-NH2

Thus, the overall decreasing order of basicities of different amines is


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569.

One of the isomer of C4H11N is optically active. It must be a

  • primary amine

  • secondary amine

  • tertiary amine

  • all isomers are optically inactive


570.

Which of the following compounds cannot be identified by carbylamine test?

  • CHCl3

  • C6H5-NH-C6H5

  • C6H5NH2

  • CH3CH2NH2


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