what is the ppt. when Zn in con. HCl is added to 3 alcohol?

Question

when Zn in Conc. HCl is added to tertiary alcohol and secondary alcohol, the solution turns cloudy.What is the ppt.?+mechanism

thx!!!

Answer 1

The reaction is known as Lucas reaction. The mechanism of the reaction is SN1, in which the reagent is concentrated HCl, with ZnCl2­ acting as the catalyst. The reaction undergoes at room temperature.
(ZnCl2 is formed by the reaction of zinc with concentrated HCl.
(Zn + 2HCl → ZnCl2 + H2)

When the reagent mixture is added to a tertiary alcohol, the precipitate of a tertiary chloroalkane is formed immediately (within 5 seconds). For example, if the tertiary alcohol is 2-methylpropan-2-ol, the precipitate is 2-chloro-2-methylpropane.
(CH3)3COH + HCl/ZnCl2 → (CH3)3CCl

When the reagent mixture is added to a secondary alcohol, the precipitate of a secondary chloroalkane is formed within 5 minutes. For example, if the secondary alcohol is propan-2-ol, the precipitate is 2-chloropropane.
(CH3)2CHOH + HCl/ZnCl2 → (CH3)2CHCl