When we were taught electrophilic aromatic substitution at our school, our teacher made us write the "rules" of di-substituted benzene concerning the decision of the substitution position based on the substituent type. One rule states that in the case of a strongly ortho-directing group and strongly-meta directing group, the ortho-directing group controls the location where the substitution will take place. Why is that so if that is the case? According to me, a strongly ortho-directing group would be a great activator and a strongly meta-directing group would be a great deactivator, hence the effect should cancel each other and the substitution could be oriented considering other factors like steric hinderance. Apologies if there is any orthodox or "awkward" language usage here, I'm primarily a high-school student.

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    $\begingroup$ At a given temperature the rate of reaction of o,p-directors>benzene>>>m-directors. m-Direction is, in effect, a default position. In the nitration of benzene the sequential introduction of nitro groups becomes more and more difficult at a given temperature. Look up the Friedel-Crafts reaction. Notice that nitrobenzene is often used as a solvent for acylating other aromatics. It doen't get acylated. Investigate the mechanism of electrophilic aromatic substitution to get a better understanding of the reasons for this behavior. $\endgroup$
    – user55119
    Jun 10 at 18:16


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