Question

Which of the following reagents can be used for distinguishing the three classes of alcohols?

• A. Fenton's reagent
• B. Lucas reagent
• C. Schiff's reagent
• D. Tollen's reagent

Answer 1

Answer: (B)

Lucas reagent can be used for distinguishing the primary, secondary and tertiary alcohols. Lucas reagent is a mixture of conc $HCl$ and anhydrous ${ZnCl}_2$.
Tertiary alcohol $\underset{\text{ reagent }}{\overset{\text{ Lucas }}{\to }}$ reacts immediately forming an oily layer in cold.
Secondary alcohol $\underset{\text{ reagent }}{\overset{\text{ Lucas }}{\to }}$ reacts within $5-10\min$
Primary alcohol $\underset{\text{ reagent }}{\overset{\text{ Lucas }}{\to }}$ does not react appreciably in cold.