Question

How will you distinguish primary and secondary alcohols using Luca's test?

Answer 1

Lucas test in alcohols is a test to differentiate between primary, secondary, and tertiary alcohols. It is based on the difference in reactivity of the three classes of alcohols with hydrogen halides.

Tertiary alcohols react immediately with Lucas reagent and turbidity appears.

Secondary alcohols react within five or so minutes (depending on their solubility).

Primary alcohols do not react appreciably with Lucas reagent at room temperature.

Hence, the time taken for turbidity to appear is used to differentiate among the three classes of alcohols.