See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: Oxygen-18 Isotope Tracking in Ester Hydrolysis **Step 1: Identify the mechanism** This is acid-catalyzed ester hydrolysis. The labeled $O^{18}$ atoms help us track which bonds break. **Step 2: Analyze the starting material** - $CH_3-C(=O^{16})-O^{18}-CH_3$ has: - $O^{16}$ in the carbonyl (C=O) - $O^{18}$ in the ether linkage (C-O-C) - $H_2O^{16}$ (normal water) is the reagent **Step 3: Determine which bond breaks** In ester hydrolysis, the **C-O bond breaks** (the ether linkage between the carbonyl and the alcohol part), not the C=O bond. This is well-established from mechanistic studies. **Step 4: Track the isotopes** - The $C-O^{18}$ bond breaks - Products formed: - **Carboxylic acid**: $CH_3-C(=O^{16})-OH$ (the oxygen in C=O remains $O^{16}$) - **Alcohol**: $C_2H_5-O^{18}H$ (the $O^{18}$ stays with the ethyl group) **Step 5: Match with options** The products are $CH_3-C(=O^{16})-OH$ and $C_2H_5-O^{18}H$, which corresponds to **option (C)**. **Why (C) is correct:** The $O^{18}$ label stays with the alcohol product, confirming that the C-O(ether) bond breaks, not the C=O bond.