See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the parent structure: The molecule contains a benzene ring with three substituents: an ethyl ester (-COOEt) group, a chloro (-Cl) group, and a thiol (-SH) group. Step 2 - Assign numbering: The ethyl ester (-COOEt) is at position 1 (it is the principal characteristic group for naming as a carboxylic acid derivative). The Cl is at position 3, and the SH is at position 4. Step 3 - Understand the reaction context: The question asks about naming or transforming this compound. The given answer is 'ethyl 4-(chlorocarbonyl)benzoate,' which means the product has a -COCl (acid chloride) group at position 4 and an ethyl ester (-COOEt) at position 1. Step 4 - Reaction of thiol with a chlorinating agent: The -SH group at position 4, when treated with an appropriate reagent (such as SOCl2 or similar), does not directly give an acid chloride. However, reconsidering the structure: the compound shown has -COOEt at C1, Cl at C3, and SH at C4. The correct answer 'ethyl 4-(chlorocarbonyl)benzoate' indicates a -COCl at C4 and -COOEt at C1, suggesting the SH group is on a carbonyl carbon (-C(=O)SH, a thiocarboxylic acid), not a ring carbon directly. Step 5 - Reinterpret the structure: The SH is actually attached to a carbonyl group making it a thiocarboxylic acid (-COSHgroup) at C4, with -Cl at C3, and -COOEt at C1. Treatment with HCl or a chlorinating agent converts -COSH to -COCl (thiocarboxylic acids react to give acid chlorides). Step 6 - Conversion: -C(=O)SH + HCl → -C(=O)Cl + H2S. This converts the thiocarboxylic acid group at position 4 into an acid chloride (carbonyl chloride), giving ethyl 4-(chlorocarbonyl)benzoate. Step 7 - Final name: The product has an ethyl ester at C1 (named as ethyl benzoate base) and a chlorocarbonyl (-COCl) group at C4, giving the IUPAC-style name ethyl 4-(chlorocarbonyl)benzoate. Therefore, the correct answer is ethyl 4-(chlorocarbonyl)benzoate.