Why is the reactivity of all the three classes of alcohols with conc. HCl and ZnCl2 (Lucas reagent) different?
Why is the reactivity of all the three classes of alcohols with conc. HCl and ZnCl2 (Lucas reagent) different?

This is due to the alkyl group’s steric barrier and the carbocation’s stability.

Because the 1° carbocation is the least stable, primary alcohol has no reaction at ambient temperature.

At ambient temperature, secondary alcohol does not look turbid, but when heated, turbidity emerges.

Since of the greater stability of the carbocation, tertiary alcohol displays turbidity almost quickly after adding Lucas reagent because they may easily create halides.