Question

Following groups exert any one of the effects on electrophilic aromatic substitution

Identify whether all three are:

• A. Weakly activating
• B. Deactiviting
• C. Moderately activating
• D. Strongly activating

Answer 1

The Correct Option is B

In electrophilic aromatic substitution reactions, substituents on the aromatic ring can either activate or deactivate the ring towards incoming electrophiles. These substituents also influence the position at which substitution is likely to occur (ortho, meta, or para).

Let's analyze the effects of the given groups:

1. OC₂H₅ (ethoxy group): This group is an electron-donating group due to the +R (resonance) effect of the oxygen. This usually makes it mildly activating and ortho/para-directing.
2. NHCOCH₃ (acetamido group): This group can donate electrons through resonance via the nitrogen atom, mildly activating the ring. It is usually ortho/para-directing but not strongly activating.
3. OCH₃ (methoxy group): This is another electron-donating group due to resonance, activating and ortho/para-directing, but like the ethoxy group, it is only weakly activating.

Despite these groups having activating effects to some extent, the question requires identifying the collective behavior of the groups when exerting an effect on electrophilic aromatic substitution. Under certain conditions, specifically through inductive effects or specific structural alterations, these groups could also be considered deactivating when they do not significantly activate or could partake in another form of interaction leading to a net deactivation of substituents.

The correct answer is Deactivating because, as a collective cluster of substitutions in this example, they result in a net effect which does not promote an increase in reaction rate under regular conditions or due to competitive negative inductive effects.