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प्रश्न
Arrange the following.
In decreasing order of the pKb values C2H5NH2, C6H5NHCH3, (C2H)2NH and CH3NH2.
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उत्तर
Due to the delocalization of the lone pair of electrons of the N-atom over the benzene ring, C6H5NHCH3 is far less basic than C2H5NH2, (C6H5)2NH and CH3NH2. Among C2H5NH2 and (C2H5)NH, (C2H5)2NH is more basic than C2H5NH2 due to the greater +I effect of the two C2H5 groups and stabilization of its conjugate acid by H-bonding.
Compare to Ethyl and methyl group, C2H5 – group has a more +I effect than CH3 – group. Therefore methylamine is weak base than ethylamine. Combining all these facts the relative basic strength of these four amines decreases in order.
(C2H5)2NH > C2H5NH2 > CH3NH2 > C6H5NHCH3
Since a stronger base has a lower pKb value, therefore pKb values decrease in the reverse order.
C6H5NHCH3 > CH3NH2 > C2H5NH2 > (C2H5)2NH
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संबंधित प्रश्न
Choose the most correct option.
Identify ‘B’ in the following reactions
\[\ce{CH3 - C ≡ N ->[Na/C2H5OH] A ->[NaNO2/dilHCl]B}\]
The order of basic strength for methyl substituted amines in aqueous solution is ____________.
Which of the following amines does not undergo acetylation?
Write a short note on the following.
Mustard oil reaction
Arrange the following:
In increasing order of solubility in water:
C6H5NH2, (C2H5)2NH, C2H5NH2
Arrange the following.
In increasing order of boiling point C6H5OH, (CH3)2NH, C2H5NH2.
Arrange the following.
In decreasing order of basic strength
Identify A, B and C.
\[\ce{CH3 - NO2 ->[LiAlH4] A ->[2CH3CH2Br] B ->[H2SO4] C}\]
Arrange the following in the increasing order of their basic strength:
C2H5NH2, C6H5NH2, (C2H5)2NH
\[\begin{array}{cc}
\ce{O}\phantom{.........}\\
||\phantom{.........}\\
\ce{H - \underset{(A)}{C} - NH - CH3}
\end{array}\]
and
\[\begin{array}{cc}
\ce{O}\\
||\\
\ce{CH3 - \underset{(B)}{C} - NH2}
\end{array}\]
are which type of isomers?
