Which alcohol reacts immediately with Lucas reagent (anhydrous ZnCl2 in conc. HCl) at room temperature to form an insoluble cloudiness/turbidity?
Answer and explanation
Correct answer: B. 2-Methylpropan-2-ol (tert-butanol)
- Step 1: Lucas reagent converts alcohols to alkyl chlorides via an SN1 pathway (for tertiary/secondary). Step 2. Tertiary alcohols form stable tertiary carbocations immediately (< 1 min), causing visible turbidity from insoluble alkyl chloride. Step 3. Secondary alcohols take 5 minutes, and primary alcohols do not react at room temperature. Answer: 2-Methylpropan-2-ol (tert-butanol). Why not the others: 1-Propanol, ethanol, and methanol are primary alcohols that remain clear at room temperature.
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