See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the parent chain and ring: The compound is a benzene ring with three substituents, so the parent name is benzoic acid (since one substituent is –COOH, which defines C-1 by IUPAC convention). Step 2 - Identify all substituents and their positions: • C-1: –COOH (carboxylic acid) — this carbon defines position 1 and gives the parent name 'benzoic acid'. • C-2 (ortho to –COOH): –CHO (formyl/aldehyde group). • C-4 (para to –COOH): –SO3H (sulfonic acid group). Step 3 - Apply nomenclature rules: • The principal characteristic group for naming the parent is –COOH → benzoic acid. • The –CHO group at C-2 is named as a prefix 'formyl-' (since –COOH is the principal group) at position 2. • The –SO3H group at C-4 is named as a prefix 'sulpho-' at position 4. • Numbering: C-1 = COOH, going around the ring to give the lowest locants to the other substituents: C-2 = CHO (ortho), C-4 = SO3H (para). This gives locants 2 and 4, which is correct. Step 4 - Assemble the name: 2-formyl-4-sulphobenzoic acid. Step 5 - Verify: 'formyl' denotes –CHO at position 2 (ortho), 'sulpho' denotes –SO3H at position 4 (para), and 'benzoic acid' is the parent with –COOH at position 1. The structure in the image matches exactly: COOH at bottom, CHO ortho to COOH, SO3H para to COOH. Therefore, the correct answer is 2-formyl-4-sulphobenzoic acid.