What is the correct order of reactivity of alcohols in the following reaction?

\(\mathbf{R}-\mathbf{O H}+\mathbf{H C l} \xrightarrow{\mathrm{ZnCl}_{2}} \mathbf{R}-\mathbf{C l}+\mathbf{H}_{2} \mathbf{O}\)

CONCEPT:

Reactivity of Alcohols

• The reactivity of alcohols with hydrochloric acid (HCl) in the presence of zinc chloride (ZnCl₂) follows a specific order based on the structure of the alcohol.
• Zinc chloride acts as a catalyst in this reaction, converting alcohols into alkyl chlorides through the formation of a carbocation intermediate.

EXPLANATION:

• The reactivity order of alcohols can be explained by the stability of the carbocation intermediate formed during the reaction.
• The stability of carbocations follows the order:
  • 3^o (tertiary) > 2^o (secondary) > 1^o (primary).
• In the given reaction:
  • R-OH + HCl → R-Cl + H₂O (in the presence of ZnCl₂).
• The tertiary alcohols (3^o) form the most stable carbocation and react the fastest.
• The secondary alcohols (2^o) form less stable carbocations compared to tertiary but more stable than primary.
• The primary alcohols (1^o) form the least stable carbocations and react the slowest.

Therefore, the correct order of reactivity of alcohols in the given reaction is 1^o < 2^o < 3^o.