![o-Toluidine][1] ![o-Toluic Acid][2] [1]: https://i.sstatic.net/IrZpvs.png [2]: https://i.sstatic.net/nlLYys.jpg When comparing o,m,p-toluidine, basicities, *ortho effect* is stated as a reason why o-toluidine is weaker But, When comparing o,m,p-toluic ccid basicities, *ortho effect* is stated as a reason why o-toluic acid is stronger acid. Further, I was given the definition that *ortho effect* is an effect in which an ortho- group causes steric hindrance, forcing the $\ce{-COOH}$ or $\ce{-NH2}$ or some other bulky group to move out of the plane, inhibiting resonance. Then, if ortho effect inhibits resonance, why is o-toluic acid the strongest and o-toluidine the weakest? Where am I going wrong in my understanding of the ortho effect?