See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

The key principle governing nucleophilic carbonyl addition reactivity is electrophilicity of the carbonyl carbon. Greater positive character on the carbonyl carbon (from electron-withdrawing inductive/resonance effects or reduced steric hindrance) increases reactivity toward nucleophilic addition. Set (1): A vs B In A (ClCH2-adjacent: BrCH2-C(=O)-CH3), the electronegative Br is on the alpha carbon directly adjacent to C=O, withdrawing electron density inductively more effectively than in B where Br is on the beta carbon (two carbons away). Greater inductive withdrawal in A makes the carbonyl carbon more electrophilic. Answer: A. Set (2): A vs B In A (diacetyl, CH3-CO-CO-CH3), two carbonyl groups are adjacent. Each carbonyl withdraws electrons from the other, making both more electrophilic. In B (butanone), there is only one carbonyl with an alkyl group donating electrons. The mutual electron-withdrawal in A increases reactivity. Answer: A. Set (3): A vs B In A (p-methoxybenzaldehyde), the -OCH3 group is electron-donating by resonance into the ring and further into the aldehyde carbonyl, decreasing electrophilicity. In B (p-nitrobenzaldehyde), the -NO2 group is strongly electron-withdrawing by resonance, increasing the electrophilicity of the aldehyde carbonyl carbon. Answer: B. Set (4): A vs B In A (p-tolualdehyde, ArCHO), the aromatic ring delocalizes electron density onto the carbonyl by resonance, reducing electrophilicity, and the para-methyl group is electron-donating. In B (acetaldehyde, CH3CHO), the methyl group is a weaker donor than an aryl group, and there is no resonance delocalization reducing carbonyl electrophilicity. Acetaldehyde is also less sterically hindered. Answer: B. Set (5): A vs B Cyclopropanone (3-membered ring) is much more reactive than cyclopentanone (5-membered ring) toward nucleophilic addition. The small ring angle strain in cyclopropanone means the carbonyl carbon is forced to adopt geometry closer to sp3 in the transition state, which relieves ring strain (the ring goes from ~60° bond angles toward the tetrahedral ~109°). This strain relief accelerates addition. Cyclopentanone has near-ideal ring geometry and no such driving force. Answer: A. Set (6): A vs B In A, the CHO group is on the aromatic ring at a position where the nitrogen lone pair (from the NH of the tetrahydroisoquinoline) can donate electron density through the aromatic ring to the aldehyde via resonance, reducing its electrophilicity. In B, the CHO is positioned such that it is less influenced by nitrogen donation (different positional relationship in the tetrahydroquinoline framework makes N lone pair donation to the CHO position less effective through resonance), leaving the carbonyl more electrophilic. Answer: B. Set (7): A vs B In B, the aldehyde carbonyl at C1 of the chromanone/isochromanone system is flanked by the lactone (ester) carbonyl, providing an additional electron-withdrawing group directly adjacent or in conjugation, further activating the CHO toward nucleophilic attack. In A, the CHO is at C4 of the chroman ring, less influenced by the lactone. The additional electron withdrawal in B makes it more reactive. Answer: B. Set (8): A vs B In B, the CHO-bearing carbon also carries a Cl substituent (an electronegative halogen directly on the same carbon as CHO, making it an alpha-chloroaldehyde). The inductive electron-withdrawal of Cl directly on the same carbon as the aldehyde significantly increases the electrophilicity of the carbonyl carbon. In A, the CHO is on a plain CH carbon with no such activating group. Answer: B. Set (9): A vs B In A (acetophenone, Ph-CO-CH3), one side is a phenyl group (electron-withdrawing by induction but donating by resonance) and one side is methyl. In B (benzophenone, Ph-CO-Ph), both sides are phenyl groups providing more resonance delocalization of the carbonyl, reducing electrophilicity, and also providing greater steric hindrance from two aryl rings. Acetophenone has less steric crowding and the methyl group donates less electron density by resonance than a second aryl group. Therefore acetophenone is more reactive. Answer: A. Set (10): A vs B In A (butanone, CH3-CO-CH2CH3), it is a dialkyl ketone. In B (benzaldehyde, Ph-CHO), despite the aryl group's resonance donation reducing carbonyl electrophilicity compared to aliphatic aldehydes, aldehydes are generally more reactive than ketones toward nucleophilic addition because: (1) aldehydes have one H (not an alkyl group) on the carbonyl, so less steric hindrance, and (2) alkyl groups are more electron-donating than H, making the ketone carbonyl less electrophilic. Benzaldehyde, even with aromatic resonance delocalization, is still an aldehyde and more reactive than butanone (a ketone). Answer: B. Therefore, the correct answer is {"set1": "A", "set2": "A", "set3": "B", "set4": "B", "set5": "A", "set6": "B", "set7": "B", "set8": "B", "set9": "A", "set10": "B"}.