Question

The order of reactivity of the following alcohols towards conc. HCl is

• A. $I>II>III>IV$
• B. $I>III>II>IV$
• C. $IV>III>II>I$
• D. $IV>III>I>II$

Answer 1

Answer: (C)

The order of reactivity depends upon the stability of the carbocations formed
Stability of carbocations is in the order
$\underset{\text{I(2∘, F nearer)}}{FC{H}_2\stackrel{+}{C}HC{H}_3}<\underset{\text{II(2∘, F away)}}{FC{H}_{2}C{H}_2\stackrel{+}{C}HC{H}_3}<\underset{\text{III(2∘)}}{C{H}_3\stackrel{+}{C}HC{H}_3}<\underset{\text{IV (Benzyl)}}{ph\stackrel{+}{C}{H}_2}$
Hence the order of relative reactivity of the alcohols will follow the order: IV > III > II > I