See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the functional groups and backbone. The molecule contains an amide group (C=O connected to NH), a terminal alkene on the nitrogen substituent, and an internal alkene in the acyl chain. Step 2: Name the acyl (acid-derived) portion. Starting from the carbonyl carbon, count the longest carbon chain that includes the C=O carbon and the internal double bond: C1(=O)-C2H2-C3H2-C4H2-C5H=C6H-C7H2-C8H3. This gives an 8-carbon chain with a double bond starting at C5, so the parent acid is oct-5-enoic acid, making the acyl part 'oct-5-en-1-amide' → 'oct-5-enamide'. Step 3: Determine the geometry of the internal double bond. The double bond at C5-C6 has an ethyl group on C6 and the chain continuing on C5. Looking at the drawn structure, the two larger groups (the chain toward carbonyl on C5, and the ethyl on C6) are on opposite sides of the double bond, indicating E (trans) configuration. Hence the prefix is (5E). Step 4: Name the N-substituent. The nitrogen bears a prop-2-en-1-yl (allyl) group: -CH2-CH=CH2. By IUPAC nomenclature this substituent is 'prop-2-en-1-yl', but the preferred IUPAC name for N-substituted amide uses 'N-(prop-2-en-1-yl)' or equivalently 'N-(prop-2-en-yl)'. Step 5: Assemble the full name. Combining everything: (5E)-N-(prop-2-en-1-yl)oct-5-enamide, which is given as (5E)-N-(prop-2-en-yl)oct-5-enamide. Therefore, the correct answer is (5E)-N-(prop-2-en-yl)oct-5-enamide.