Question

ΝΗ,
Select the basic strength order of following molecules.
NH
NH
NH
CC13
(0)
(m)
(p)
CCL
CCI
as Aniline >p>m> o (b) Aniline >m>p> o
(Aniline
(c) p > > Aniline >m​

Answer 1

Answer:

The pKa values of m - nitroaniline, p - nitroaniline and o - nitroaniline isomers are 2.5, 1.0 and -0.3 respectively.

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

In the ortho position, a very close inductive effect of the nitro group is also observed. (ortho effect) Hence, o - nitroaniline is less basic than p - nitroaniline.

In m - nitroaniline, only the inductive effect is present.

The decreasing order of basicity is m - nitroaniline > p - nitroaniline > o - nitroaniline.