Question

basic strength order of Aniline meta chloroaniline Ortho chloroaniline para chloroaniline​

Answer 1

Answer:

A base is species that abstracts the proton.

Two electronic effects occurs here +R and -I.

Above compounds by accepting proton will get protonated to form NH3+ form. Benzene ring has three conjugate bonds which are delocalised. Hence stabilizes the +ive charge and availability of electrons on nitrogen atom.

The resonance structures will have +ive charge on ortho and para postions. In para position this is stabilized, whereas in ortho it further get electron deficient, as explained:

At para: +R effect of cl will increase electron density at para position make the structure stable.

At ortho: +R effect will be opposed by strong -I effect.

At meta: no R effect , only -I effect (less effective due to distance)

Aniline: no +R effect and no -I effect.

Chlorine has -I inductive effect due to its electronegativity. It get decreases with distance. Therefore it decreases electron density at ortho (more) and para position (neligible). Since there is already +ive charge at ortho and para positions (resonance), further pulling of electrons by cl atom will make structure unstable in case of ortho. Hence affect stabilization of ortho n para products and hence their basicity. No such unstable structures found in aniline

Explanation:

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