See image — Reaction Mechanism Chemistry Question

💡 Solution & Explanation

Concept: The carbylamine reaction (isocyanide synthesis) involves the reaction of a primary amine with chloroform (CHCl3) in the presence of alcoholic KOH to form an isocyanide (carbylamine). Step 1: Write the overall reaction. C6H5NH2 + CHCl3 + KOH --> C6H5NC + KCl + H2O Step 2: Understand the mechanism. CHCl3 is first dehydrohalogenated by KOH to form dichlorocarbene (:CCl2): CHCl3 + KOH --> :CCl2 + KCl + H2O This step consumes 1 mole of KOH. Step 3: The dichlorocarbene reacts with the primary amine (aniline) to form an intermediate: C6H5NH2 + :CCl2 --> C6H5NH-CHCl2 Step 4: The intermediate loses 2 moles of HCl, each neutralized by KOH: C6H5NH-CHCl2 + 2KOH --> C6H5NC + 2KCl + 2H2O This step consumes 2 moles of KOH. Step 5: Total KOH consumed = 1 (for carbene formation) + 2 (for dehydrohalogenation of intermediate) = 3 moles. Why other options fail: - (a) 1: Only accounts for one step, not the full mechanism. - (b) 2: Accounts for only the second dehydrohalogenation steps, missing the first. - (d) 4: Overcounts; only 3 moles of KCl are produced per mole of CHCl3, confirming 3 moles KOH. Therefore, the correct answer is C.