See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Concept: Nucleophilic acyl substitution mechanism. Step 1: Identify the reaction. Acetyl chloride (CH3-C(=O)-Cl) reacts with ammonia (NH3). The overall product of this reaction is acetamide (CH3-C(=O)-NH2) with loss of HCl. Step 2: Understand the mechanism. Nucleophilic acyl substitution proceeds via a tetrahedral intermediate. The nucleophile (NH3) attacks the electrophilic carbonyl carbon of acetyl chloride. Step 3: Formation of the intermediate. When NH3 attacks the carbonyl carbon of CH3-C(=O)-Cl, the pi bond of C=O breaks and the oxygen becomes negatively charged (O-), while the carbon now bears four substituents: CH3, O-, Cl, and the incoming NH3 which becomes N(+)H3 (protonated because it donated its lone pair). This gives the tetrahedral intermediate: CH3-C(O-)(Cl)-N(+)H3. Step 4: This matches option (d): a tetrahedral carbon bearing CH3, O-, Cl, and N(+)H3 groups. Step 5: Why other options fail: - (a) CH3-N(+)H3 is simply methylammonium; not related to the acyl substitution mechanism. - (b) CH3-C(=O)(+) is the acetylium cation; this would be an intermediate in an SN1-type pathway, not the typical nucleophilic addition-elimination tetrahedral intermediate. - (c) Shows a carbon with two Cl atoms and an OH group, which does not correspond to attack of NH3 on acetyl chloride. Therefore, the correct answer is D.