Alcohols, Phenols and Ethers Part 1

Tertiary alcohols react fastest with conc. HCl and anhydrous ZnCl2 (lucas reagent) as its mechanism proceeds through the formation of stable tertiary carbocation.
Mechanism
Step 1: Step 2 : (CH3)3C−O+H2⇌

(CH3)C++H2O

3∘‌Carbocation

Step 3: (CH3)3C++Cl−⇌

(CH3)3C−Cl

t−Butyl chloride