See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Concept: Boiling point depends on intermolecular forces — hydrogen bonding, dipole-dipole interactions, and London dispersion forces. Compounds capable of intermolecular hydrogen bonding (N-H or O-H donors) have significantly higher boiling points than structurally similar compounds that cannot form such H-bonds. Analysis of each option: Option (a): Cyclopropanol (first) vs. oxetane (second). Cyclopropanol has an -OH group and can form intermolecular hydrogen bonds. Its boiling point is ~101°C. Oxetane is a cyclic ether with no O-H or N-H; it can only act as H-bond acceptor but not donor. Its boiling point is ~48°C. So the FIRST compound (cyclopropanol) has a higher boiling point. This does NOT satisfy the condition. Option (b): Acetone (first, bp ~56°C) vs. 2-methylpropene (isobutylene, second, bp ~-7°C). Acetone has a polar C=O group and a higher boiling point than isobutylene, which is a simple alkene with only weak London dispersion forces. The FIRST compound has a higher boiling point. This does NOT satisfy the condition. Option (c): Ethylene glycol (HO-CH2-CH2-OH, first, bp ~197°C) vs. 1-propanol (CH3-CH2-CH2-OH, second, bp ~97°C). Ethylene glycol has two -OH groups, enabling extensive intermolecular hydrogen bonding, giving it a much higher boiling point than 1-propanol. The FIRST compound has a higher boiling point. This does NOT satisfy the condition. Option (d): 1-Methylpyrrolidine (first) vs. piperidine (second). 1-Methylpyrrolidine is a tertiary amine (N-CH3, no N-H), so it CANNOT form N-H...N hydrogen bonds. Its boiling point is ~80°C. Piperidine is a secondary amine with an N-H group, allowing intermolecular hydrogen bonding. Its boiling point is ~106°C. Therefore, the SECOND compound (piperidine) has a higher boiling point than the first compound (1-methylpyrrolidine). This SATISFIES the condition. Why other options fail: In (a), (b), and (c), the first compound either has stronger H-bonding, polarity, or more -OH groups than the second, giving the first compound the higher boiling point. Therefore, the correct answer is D.