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M.A.R.
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In the presence of bulky group that is methyl in this case causes steric hinderence making the plane the NH3$\ce{NH3}$ out the plane thus preventing resonance which could have helps it in delocalising the + charge thus making the conjugate base very stable but because of hindernce the + charge gets localized and makes the conjugate base unstable and so the acid weaker.

But in case of o-toluic acid if one draws the resonating structures of the conjugate base we see that benzene ring exerts +m (mesomeric) effect, which is not so in case of o-toluidine,which which indeed is inversly proportional to acidic strength and so the non planarity caused due SIR now benefits the substituent by making it free from the +M effect of the ring and so increasing its acidity.now Now the substituent can freely make equivalent resonance which can will support the acidity and will not be harmed by the rings +M.

In the presence of bulky group that is methyl in this case causes steric hinderence making the plane the NH3 out the plane thus preventing resonance which could have helps it in delocalising the + charge thus making the conjugate base very stable but because of hindernce the + charge gets localized and makes the conjugate base unstable and so the acid weaker

But in case of o-toluic acid if one draws the resonating structures of the conjugate base we see that benzene ring exerts +m (mesomeric) effect, which is not so in case of o-toluidine,which indeed is inversly proportional to acidic strength and so the non planarity caused due SIR now benefits the substituent by making it free from the +M effect of the ring and so increasing its acidity.now the substituent can freely make equivalent resonance which can will support the acidity and will not be harmed by the rings +M

In the presence of bulky group that is methyl in this case causes steric hinderence making the plane the $\ce{NH3}$ out the plane thus preventing resonance which could have helps it in delocalising the + charge thus making the conjugate base very stable but because of hindernce the + charge gets localized and makes the conjugate base unstable and so the acid weaker.

But in case of o-toluic acid if one draws the resonating structures of the conjugate base we see that benzene ring exerts +m (mesomeric) effect, which is not so in case of o-toluidine, which indeed is inversly proportional to acidic strength and so the non planarity caused due SIR now benefits the substituent by making it free from the +M effect of the ring and so increasing its acidity. Now the substituent can freely make equivalent resonance which can will support the acidity and will not be harmed by the rings +M.

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nurd
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In the presence of bulky group that is methyl in this case causes steric hinderence making the plane the NH3 out the plane thus preventing resonance which could have helps it in delocalising the + charge thus making the conjugate base very stable but because of hindernce the + charge gets localized and makes the conjugate base unstable and so the acid weaker

But in case of o-toluic acid if one draws the resonating structures of the conjugate base we see that benzene ring exerts +m (mesomeric) effect, which is not so in case of o-toluidine,which indeed is inversly proportional to acidic strength and so the non planarity caused due SIR now benefits the substituent by making it free from the +M effect of the ring and so increasing its acidity.now the substituent can freely make equivalent resonance which can will support the acidity and will not be harmed by the rings +M