Given below are two statements: Statement I: In the Lucas test, primary, secondary and tertiary alcohols are distinguished on the basis of their reactivity with conc. $\mathrm{HCl}$ + $\mathrm{ZnCl}{}_2$, known as Lucas reagent. Statement II: Primary alcohols are most reactive and immediately produce turbidity at room temperature on reaction with Lucas reagent. In the light of the above statements, choose the most appropriate answer from the options given below:

Solution & Explanation

\textbf{Answer:} (C) Statement I is correct but Statement II is incorrect. \textbf{Solution:} Statement I is correct: the Lucas reagent (conc. $\mathrm{HCl}$ + anhydrous $\mathrm{ZnCl}{}_2$) distinguishes 1${}^{\circ }$, 2${}^{\circ }$ and 3${}^{\circ }$ alcohols by the rate at which they form the insoluble alkyl chloride (turbidity). Statement II is incorrect: tertiary alcohols are MOST reactive (instant turbidity, via a stable 3${}^{\circ }$ carbocation), secondary react in about 5 minutes, while primary alcohols do not react at room temperature. So primary alcohols are the least reactive, not the most.