Question

Lucas reagent will give instant turbidity with:

• A. primary alcohol
• B. secondary alcohol
• C. tertiary alcohol
• D. methane

Answer 1

Answer: (C)

Lucas reagent is a mixture of anhy. $ZnC{l}_2$ and cone. $\text{HCl}\text{.}$ It is used to distinguish the primary, secondary and tertiary alcohols. $\underset{(Tertiaryalcohol)}{R-\underset{R}{\stackrel{R}{\underset{|}{\stackrel{|}{C}}}}OH+HCl}\underset{\text{at}\text{room}\text{temp}\text{.}}{\overset{\text{anhy}\text{.ZnC}{\text{l}}_{\text{2}}}{\to }}$ $R-\underset{R}{\stackrel{R}{\underset{|}{\stackrel{|}{C}}}}-Cl+\underset{(water)}{H_{2}O}\left[\begin{array}{rl}& \text{while}\\ & \text{turbidity}\\ & \text{immediately}\end{array}\right]$ Secondary alcohols give white turbidity within 1-2 minute and primary alcohols give white turbidity only on heating.