Which- of the following reactions .cannot be used for the preparation of alkyl halides?

Options

A. `CH_(3)CH_(2)OH + HCl overset("anhyd" ZnCl_(2)) to`
B. `CH_(3)CH_(2)OH + HCl to`
C. `(CH_(3))_(3)COH + HCl to`
D. `(CH_(3))_(2)CHOH + HCl overset("anhyd" ZnCl_(2)) to`

Answer

B

Explanation

In case of primary and secondary alcohols, presence of anhydrous `ZnCl_2` is required as it helps in the cleavage of C-O bond. Being a Lewis acid, it coordinates with the oxygen atom-of the alcohols. As a result, C-Q bond weakens and ultimately breaks to form carbocations. These carbocations then readily react with chloride ion to form chloroalkanes. Tertiary alcohols react readily with.HCl even in the absence of `ZnCl_2`.