See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Concept: The reaction of sodium acetate (CH3COO(-)) with acetyl chloride (CH3COCl) is a nucleophilic acyl substitution reaction. The acetate anion acts as a nucleophile and attacks the electrophilic carbonyl carbon of acetyl chloride, ultimately displacing chloride to give acetic anhydride. Step 1 - Identify the nucleophile and electrophile: The carboxylate oxygen of sodium acetate (CH3COO(-)) is the nucleophile. The carbonyl carbon of acetyl chloride is the electrophile, activated by the electron-withdrawing carbonyl group and the leaving group Cl(-). Step 2 - Determine the correct arrow-pushing mechanism: In nucleophilic acyl substitution, the nucleophile attacks the carbonyl carbon. The curved arrow should go FROM the negatively charged oxygen of acetate TO the carbonyl carbon of acetyl chloride. Simultaneously (or subsequently), the pi electrons of the C=O bond can shift, forming a tetrahedral intermediate, which then collapses expelling Cl(-). Step 3 - Evaluate option (c): Option (c) shows the curved arrow originating from the O(-) of acetate and pointing toward the carbonyl carbon of CH3-C(=O)-Cl, with an additional arrow from the C=O pi bond moving upward (back onto oxygen), consistent with the addition step of nucleophilic acyl substitution forming a tetrahedral intermediate. This correctly depicts attack at the electrophilic carbonyl carbon with simultaneous rehybridization of the carbonyl. Step 4 - Why other options fail: - Option (a) shows the arrow going from O(-) directly to the carbonyl carbon but the arrow direction/depiction implies attack at the wrong site or incorrect electron flow without the accompanying pi bond shift arrow. - Option (b) shows the arrow curving in a manner suggesting SN2-type attack at the carbon bearing Cl (the alpha carbon or the C-Cl carbon), not at the carbonyl carbon, which is incorrect for acyl substitution. - Option (d) shows the nucleophile attacking the carbon bearing the chlorine in what appears to be an SN2 on a reversed structure, which is not the operative mechanism here. Therefore, the correct answer is C.