See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the structure. The molecule is: BrCH2 — CH(CONH2) — C(=O) — CH2 — CH3. This consists of a bromomethyl group (CH2Br), a CH bearing a carboxamide substituent (CONH2), a ketone carbonyl (C=O), and an ethyl group (CH2CH3). Step 2: Identify the principal characteristic group. The carboxamide (–CONH2) attached as a substituent and the ketone (C=O) are both present. However, we must decide the parent chain and principal group. The –CONH2 here is a –CONH2 group attached to a carbon in the chain (it is not a terminal –CONH2 that would make it an amide of the chain itself). The ketone is within the chain. Step 3: Determine the parent chain. Look at the longest carbon chain that includes the highest-priority functional group. The –CONH2 group can be treated as a suffix group (amide). If we include the carbon of –CONH2 in the parent chain, the chain becomes: CONH2 — CH(CH2Br) — C(=O) — CH2 — CH3, which is a 5-carbon chain (pentanamide), where the amide carbon is C1. Step 4: Number the chain. With the amide carbon as C1: - C1: CONH2 (amide carbon) - C2: CH with CH2Br substituent - C3: C=O (ketone, oxo substituent) - C4: CH2 - C5: CH3 Step 5: Name the compound. Parent chain: pentanamide (5 carbons, amide at C1). Substituents: oxo at C3 (ketone), bromomethyl (CH2Br) at C2. Name: 2-(Bromomethyl)-3-oxopentanamide. Step 6: Verify against options. - (a) '3-oxopentane carboxamide' is incorrect nomenclature style. - (b) '1-Bromo-2-carbamoylpentan-3-one' treats the ketone as parent and CONH2 as substituent; the CH2Br would be at C1 (terminal), but this numbering gives the amide lower priority than ketone as suffix, which is incorrect since amide has higher seniority than ketone. - (c) '5-Bromo-4-carbamoylpentan-3-one' uses ketone as parent and numbers from the wrong end. - (d) '2-(Bromomethyl)-3-oxopentanamide' correctly uses amide as the principal characteristic group (highest seniority), includes its carbon as C1, places the oxo at C3, and the bromomethyl substituent at C2. Therefore, the correct answer is D.