See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Step 1 - Concept: The reaction sequence converts a carboxylic acid to a nitrile via acid chloride and amide intermediates. Step 2 - Reaction 1 (Starting material + SOCl2 → A): Thionyl chloride converts the carboxylic acid (-CO2H) to an acid chloride (-COCl). The stereochemistry at C1 is retained. A = 1-methylcyclohexane-1-carbonyl chloride with the same relative configuration (CO2H on wedge, CH3 on dash). Step 3 - Reaction 2 (A + NH3 → B): Ammonia reacts with the acid chloride to give a primary amide (-CONH2). Stereochemistry at C1 is retained. B = 1-methylcyclohexane-1-carboxamide with CO2H replaced by CONH2, same configuration. Step 4 - Reaction 3 (B + P4O10, heat → C): P4O10 (phosphorus pentoxide) is a dehydrating agent that converts a primary amide (-CONH2) to a nitrile (-CN) by eliminating water. Stereochemistry at C1 is retained. C = 1-methylcyclohexane-1-carbonitrile with CN on wedge up and CH3 on dash down at C1. Step 5 - Molecular formula check: 1-methylcyclohexane-1-carbonitrile = C6H10(CH3)(CN) = C8H13N. This matches the given formula C8H13N. Confirmed. Step 6 - Stereochemistry: The CN group retains the same configuration as the original CO2H (wedge up), and CH3 remains on dash (down). This matches option (b). Step 7 - Why other options fail: - Option (a): Shows OH instead of CN; this would be an alcohol, not a nitrile, and the molecular formula would be C7H14O, not C8H13N. - Option (c): Shows CN and CH3 both on wedge (same face/cis), incorrect stereochemistry; the starting material has them on opposite faces. - Option (d): Shows CN on dash and CH3 on wedge, which is the enantiomeric/inverted configuration; no inversion occurs in this sequence. Therefore, the correct answer is B.