See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the functional groups: The structure shows a carbon chain with a terminal alkene (CH2=CH-) at one end and an aldehyde group (-CHO) at the other end. Step 2 - Count the carbons: Starting from the aldehyde carbon: C1 (CHO) - C2 (CH2) - C3 (CH2) - C4 (CH=CH2). Wait, let me recount. The structure shows CHO at the bottom connected to a chain ending in CH2=CH- at the top. Counting: C1 = aldehyde carbon (CHO), C2 = CH2, C3 = CH2, C4 = CH=CH2. That gives 4 carbons total with the double bond between C3 and C4. Step 3 - Apply IUPAC nomenclature: The parent chain is butane (4 carbons). The principal characteristic group is the aldehyde, so the aldehyde carbon is C1. The double bond is between C3 and C4, making it but-3-en-1-al, commonly written as but-3-enal (since the aldehyde is always at C1, the '1' is omitted). Step 4 - Construct the name: but (4 carbons) + 3-en (double bond starting at C3) + al (aldehyde suffix) = but-3-enal. Therefore, the correct answer is but-3-enal.