See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the parent chain. The longest carbon chain containing the principal characteristic group (carboxylic acid, -CO2H) and the double bond is counted. Starting from the carboxylic acid carbon: C1(COOH)-C2(H2)-C3(H)=C4(H)-C5(quaternary)-C6(H2OH). This gives a 6-carbon chain: hex-en-oic acid. Step 2: Locate the double bond. The double bond is between C3 and C4 (counting from the -CO2H end as C1), giving hex-3-en-1-oic acid. Wait, let me recount: C1 is the carboxyl carbon, C2 is -CH2-, C3 is =CH-, C4 is =CH-, C5 is the quaternary carbon, C6 is -CH2OH. The double bond is between C3 and C4, so the parent name is hex-3-enoic acid. Step 3: Identify substituents on the parent chain. At C5: a cyclohexyl group and a methyl group are attached. At C6: a hydroxyl group (-OH) is present (as part of -CH2OH). Step 4: Apply numbering. The carboxylic acid end is C1 to give lowest locants. The double bond is at position 3 (hex-3-en-1-oic acid, where the '1' for the acid is implied). Substituents: 5-cyclohexyl, 5-methyl, 6-hydroxy. Step 5: Assemble the IUPAC name. Parent chain: hexanoic acid. Unsaturation: 3-en. Substituents in alphabetical order: 5-cyclohexyl, 6-hydroxy, 5-methyl. Full name: 5-cyclohexyl-6-hydroxy-5-methylhex-3-en-1-oic acid. Step 6: Verify. The structure HO-CH2-C(cyclohexyl)(CH3)-CH=CH-CH2-COOH has: C1=COOH, C2=CH2, C3=CH (part of double bond), C4=CH (part of double bond), C5=C(cyclohexyl)(CH3), C6=CH2OH. Substituents at C5: cyclohexyl and methyl. Substituent at C6: hydroxy. Double bond between C3 and C4. This matches 5-cyclohexyl-6-hydroxy-5-methylhex-3-en-1-oic acid. Therefore, the correct answer is 5-cyclohexyl-6-hydroxy-5-methylhex-3-en-1-oic acid.