See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the functional groups and connectivity in the molecule. The structure is CH3-CH(CH3)-C(=O)-C(=O)-NH(Br). Reading from left to right: a methyl group, a CH with a methyl branch, a carbonyl (C=O), another carbonyl (C=O), and an NH with Br attached. Step 2: Identify the principal functional group. The rightmost group is -C(=O)-NH(Br), which is an amide (specifically an N-bromoamide). The parent chain must include the amide carbon, so the compound is named as a butanamide. Step 3: Number the chain. In amide nomenclature, the carbonyl carbon of the amide (-CONH-) is C1. So: C1 = amide carbonyl (C=O attached to NHBr), C2 = the adjacent carbonyl (C=O, a keto group), C3 = CH(CH3), C4 = CH3. Step 4: Name the substituents. There is a keto (oxo) group at C2, a methyl branch at C3, and a bromo substituent on the nitrogen (N-Bromo). Step 5: Assemble the name. The parent chain is butanamide (4 carbons including the amide carbonyl at C1). The keto group is at C2 → 2-keto. The methyl branch is at C3 → 3-methyl. The N-substituent is Br → N-Bromo. Full name: (N-Bromo)-2-keto-3-methylbutanamide. Step 6: Eliminate wrong options. Option (b) says 4-methyl, but the methyl is on C3, not C4. Option (c) incorrectly labels both carbonyls as diketo and adds 'carboxamide' unnecessarily. Option (d) names it as a propane derivative without the amide functionality. Therefore, the correct answer is A.