See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the compound structure: The compound is CH2=C(CH3)-COOCH3. This is an ester where the acid part contains a double bond and a methyl substituent, and the alcohol part is methanol (methoxy group). Step 2 - Identify the parent chain for IUPAC naming: The longest carbon chain containing both the double bond and the principal characteristic group (ester/carboxylic acid) is selected. The carboxylate group (-COOCH3) contributes one carbon, and the chain CH2=C- contributes two more carbons, giving a 3-carbon (prop) chain total. Step 3 - Name the acid portion: The parent acid chain is propenoic acid (prop-2-enoic acid). The double bond is between C2 and C3 (using the carboxylate carbon as C1), making it prop-2-enoate. There is a methyl substituent at C2, making it 2-methylprop-2-enoate. Step 4 - Name the alcohol portion: The -OCH3 group means the ester is a methyl ester, so the prefix is 'methyl'. Step 5 - Combine: The full IUPAC name is methyl 2-methylprop-2-enoate. This is actually the systematic name for methyl methacrylate. Step 6 - Why other options fail: (a) 'Methyl-2-methylprop-1-en-3-oate' incorrectly numbers the double bond as 1 and places the carbonyl at position 3, which is inconsistent with lowest-locant rules for principal characteristic groups. (b) '2-Methoxycarbonylpropene' uses substitutive nomenclature for the methoxycarbonyl group but is not the preferred IUPAC ester name format. (c) '2-Methoxycarbonylprop-2-ene' similarly uses substitutive nomenclature and is not the retained IUPAC ester name. (d) 'Methyl 2-methylprop-2-enoate' correctly names it as the methyl ester of 2-methylprop-2-enoic acid, following IUPAC ester naming conventions. Therefore, the correct answer is D.