See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Concept: IUPAC nomenclature of aldehydes with substituents requires identifying the longest carbon chain that includes the aldehyde (–CHO) group, numbering from the aldehyde carbon as C-1, and naming substituents with their positions. Step 1: Identify the structure. The compound is CH3 — CH(OCH3) — CHO. The structure has a methoxy group (–OCH3) on the middle carbon, indicated by the dashed bond shown above the CH in the image. Step 2: Identify the principal characteristic group. The –CHO (aldehyde) group is the principal characteristic group and gets the suffix '-al'. Step 3: Select the parent chain. The longest chain containing the –CHO group is three carbons: CHO–CH–CH3, giving the parent name 'propanal'. Step 4: Number the chain. The aldehyde carbon is C-1 (it must be), the middle carbon bearing the methoxy group is C-2, and the terminal methyl is C-3. Step 5: Name the substituent. The –OCH3 group is 'methoxy', located at C-2. Step 6: Assemble the name. The name is 2-Methoxypropanal. Why other options fail: - (a) 1-Formyl-1-methoxyethane: incorrect style; 'formyl' as a prefix is used only when the CHO is not part of the principal chain, and the locant/parent are wrong. - (b) 2-Methoxypropan-3-one: 'one' suffix indicates a ketone; this compound is an aldehyde, not a ketone. - (d) 2-Methoxypropan-3-al: incorrect; the aldehyde carbon must be C-1, not C-3. The locant '3-al' violates the rule that the principal characteristic group gets the lowest possible locant. Therefore, the correct answer is C.