Using resonance contributors for the carbocation intermediate, explain why a phenyl group is an ortho–para director.

Carbocations are positively charged carbon species that are stabilized by adjacent electron-donating groups. The stability of a carbocation is crucial in determining the reactivity of electrophilic aromatic substitution reactions. A more stable carbocation intermediate leads to a more favorable reaction pathway, influencing the position of substitution on the aromatic ring.

Resonance contributors are different Lewis structures that represent the same molecule, illustrating how electrons are delocalized across the structure. In the case of a phenyl group, resonance allows the positive charge of the carbocation to be shared with the aromatic ring, enhancing stability. This delocalization is key to understanding how substituents influence the reactivity and orientation of electrophilic attacks.

Ortho-para directing effects refer to the tendency of certain substituents, like phenyl groups, to direct incoming electrophiles to the ortho and para positions on an aromatic ring during substitution reactions. This is due to the resonance stabilization of the carbocation intermediates formed at these positions, which are more stable than those formed at the meta position. Understanding this directing effect is essential for predicting the outcomes of electrophilic aromatic substitutions.