See image — Aromatic Hydrocarbons Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the substituents and their directing effects: The compound has two alkyl substituents on the benzene ring - a tert-butyl group (CMe3) at position 1 and an isopropyl group (CHMe2) at position 4 (para to CMe3). Both alkyl groups are ortho/para directors and ring activators. Step 2 - Determine the positions activated by each group: CMe3 at position 1 activates ortho (positions A and D) and para (position B) positions. CHMe2 at position 4 activates ortho (positions A and C, i.e., positions 3 and 5 relative to ring numbering) and para (position 1, already occupied). Step 3 - Identify the position activated by both groups (cooperative directing): Position B is para to CMe3 (position 1) and also ortho to CHMe2 (position 4). This means both substituents cooperatively direct the incoming electrophile (NO2+) to position B. Step 4 - Consider steric effects: Position A is ortho to both CMe3 and CHMe2, making it sterically very hindered. The bulky tert-butyl group especially hinders ortho attack at positions A and D. Position B, while ortho to the isopropyl group, benefits from cooperative electronic activation by both groups and is less sterically hindered than position A. Step 5 - Why other options fail: Position A is doubly activated electronically but severely sterically hindered between two bulky groups. Positions D and C are only singly activated (by CMe3 ortho and meta respectively, with D being ortho/activated and C being meta/deactivated relative to CHMe2). Position B receives additive activation from both groups with less steric penalty than A. Therefore, the correct answer is B.