See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Step 1 - Starting material: The starting material is 1,2,3-cyclopropane tricarboxylic acid triethyl ester (all three carbons of the cyclopropane ring each bear an ethyl ester group). Step 2 - KOH (saponification): The three ethyl ester groups are hydrolyzed under basic conditions to give the tricarboxylate salt (tripotassium salt of cyclopropane-1,2,3-tricarboxylic acid). Step 3 - H3O+ (acidification): Protonation gives cyclopropane-1,2,3-tricarboxylic acid (three -COOH groups on the cyclopropane ring). Step 4 - PCl5: Converts each carboxylic acid (-COOH) to an acid chloride (-COCl), giving cyclopropane-1,2,3-tricarbonyl trichloride. Step 5 - LiAlH4: Reduces each acid chloride to a primary alcohol (-CH2OH), giving 1,2,3-tris(hydroxymethyl)cyclopropane. Step 6 - H+/Delta (acid with heat): Under acidic conditions with heating, the three primary alcohols undergo dehydration. With three -CH2OH groups on a three-membered ring under acid/heat, intramolecular and sequential dehydration/ring-opening/rearrangement occurs. The tris(hydroxymethyl)cyclopropane upon acid-catalyzed dehydration and ring opening leads to cyclization. The three -CH2- units from the hydroxymethyl groups plus the three ring carbons provide exactly six carbons. The cyclopropane ring opens under the acidic conditions, and the overall six-carbon framework cyclizes with elimination of water to form benzene (an aromatic product). This is consistent with the fact that cyclopropenyl systems and their derivatives can aromatize, and the six-carbon count (3 ring carbons + 3 CH2 groups) perfectly matches benzene's molecular formula C6H6 after loss of three water molecules. Option (a) fails because 1,2-dimethylenecyclopropane would not form from this reaction sequence. Option (c) fails because a methylenecyclohexadiene would require a different carbon framework. Option (d) fails because vinylcyclobutane would require ring expansion to a four-membered ring with no clear mechanism here. Therefore, the correct answer is B.