Solution

Alcohols react with Lucas reagent (conc. HCl + anhyd. $ZnCl_2$) via a carbocation intermediate, forming an alkyl chloride (turbidity). A tertiary carbocation is more stable than secondary or primary, so tertiary alcohols react instantaneously. 2-methylpropan-2-ol (tert-butyl alcohol), $(CH_3)_3C-OH$, is tertiary, so it reacts instantaneously.

Concept Reactivity order of 1°, 2°, 3° alcohols with Lucas reagent

Alcohols, Phenols and Ethers in past papers

65 questions from this chapter have appeared across 26 exam years.