Question

The effect of activation or deactivation of an incoming functional group to an aromatic compound is strongest at

• A. Only ortho position
• B. Only meta position
• C. Only para position
• D. Both ortho and para positions

Answer 1

The Correct Option is D

The question asks about the effect of activation or deactivation by an incoming functional group on an aromatic compound. This phenomenon is related to the concept of substituent effects in electrophilic aromatic substitution reactions.

Electrophilic Aromatic Substitution (EAS): In EAS, the presence of substituents on an aromatic ring can affect the reactivity and orientation of further substitution reactions.

• Activating groups direct new substituents to ortho and para positions because they increase the electron density on the aromatic ring, making these positions more nucleophilic, or reactive towards electrophiles.
• Deactivating groups typically direct new substituents to the meta position because they withdraw electron density, making the ortho and para positions relatively less reactive towards electrophiles.

Reasoning: For substituents that are either activating or moderately deactivating, the effect is most pronounced at the ortho and para positions. This is because of the electron-donating resonance (for activators) or the lack of resonance stabilization (for deactivators) at these positions compared to the meta position.

Conclusion: The effect of an activating or deactivating group is strongest at both the ortho and para positions. This is why the correct answer is:

Both ortho and para positions

Thus, the option "Both ortho and para positions" is the correct choice. This understanding is crucial for predicting the outcomes of aromatic substitution reactions in organic chemistry.