Question

Why can only the tertiary and secondary alcohol react in Lucas reagent?

Answer 1

It is wrong that the reaction of 1° alochol with Lucas reagent is not possible rather it is true that it takes long time . The reaction may take from 10 minutes to several days.

Explanation:

When primary alcohol reacts with Lucas reagent, ionization is not possible because primary carbocation is too unstable. So the reaction does not follow SN1 mechanism. Primary alcohol reacts by SN2 mechanism which is slower than SN1 mechanism.
For example, in the reaction
Butan 1 ol + Lucas reagent
At first `ZnCl_2` attack the alcohol and form a ionic compound and then cl- ion attacks the complex from the back, displacing the leaving group. But it is a fact to remember that ionic compound formed in the reaction of butan 1 ol and zncl2 remains in the solution until it is attacked by the chloride ion.