Which of the following orders is true regarding the basic nature of $\mathrm{NH}_{2}$ group?

Which of the following orders is true regarding the basic nature of $\mathrm{NH}_{2}$ group?
  1. $o$-Toluidine $>$ Aniline $>o$-Nitroaniline
  2. $o$-Toluidine $ < $ Aniline $>o$-Nitroaniline
  3. $o$-Toluidine $ < $ Aniline $ < o$-Nitroaniline
  4. $o$-Toluidine $>$ Aniline $ < o$-Nitroaniline

Solution

Electron-releasing group increases the availability of lone pair of electrons on nitrogen while electron attracting group decreases this availability.
The correct order of basic strength of aromatic amines is o $-$ Toluidine $ < $ Aniline $>0-$ Nitroaniline.
Aniline is more basic than ortho nitro aniline because the presence of electron withdrawing nitro group decreases the ease with which $\mathrm{N}$ can donate a lonepair of electrons.
o-Toluidine is less basic than aniline because whenever a substituent is present in the ortho position, it decreases its basicity.

Asked in: JEE-TOPICTESTS-CHEMISTRY

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