Question

Lucas test of alcohols involves the following reaction:
$R-OH+\underset{Conc}{HCl}\stackrel{AnhydrousZnc{l}_2}{\to }RCl+H_{2}O$
Select the correct statements.

• A. ROH behaves as a base.
• B. Lesser is the acidic character of alcohol, greater is its reactivity towards Lucas reagent.
• C. Reactivity of $1^0,2^0,3^0$ alcohol lies in the following sequence (for Lucas reaction) - $3^0>2^0>1^0$
• D. $C{H}_{3}OH$ gives Lucas test most quickly

Answer 1

Answer: (A), (B), (C)

ROH behaves as a base.
Lesser is the acidic character of alcohol, greater is its reactivity towards Lucas reagent.
Reactivity of $1^0,2^0,3^0$ alcohol lies in the following sequence (for Lucas reaction) - $3^0>2^0>1^0$

ROH behaves as a base, as it reacts with the acid, HCl.
Alcohols are basic in nature. Phenol is not tested by Lucas test as it is acidic.
Tertiary alcohols react instantly with Lucas reagent. Secondary alcohol takes some time to react. Primary alcohol does not react with lucas reagent at room temperature. This is because the negative charge of R group is stabilized more by an alpha carbon rather than an hydrogen attached to the carbon.