Question

Which one of the following alcohols reacts instantaneously with Lucas reagent?

Options

• \[\begin{array} {c}\mathrm{CH_3-CH-CH_2OH} \\ \mathrm{CH_3} \end{array}\]

• \[\begin{array}{cc}
  \phantom{....}\ce{CH3}\\
  \phantom{.}|\\
  \phantom{.}\ce{CH3-C-OH}\phantom{..}\\
  \phantom{.}|\\
  \phantom{.}\ce{CH3}
  \end{array}\]

• \[\mathrm{CH_{3}-CH_{2}-CH_{2}-CH_{2}OH}\]

• \[\begin{array}{cc}
  \phantom{....}\ce{CH3}\phantom{..}\ce{CH2}\phantom{..}\ce{CH}\phantom{..}\ce{OH}\phantom{..}\\
  \phantom{..........}|\phantom{}\\
  \phantom{...............}\ce{CH3}\phantom{..}\\
  \end{array}\]

Answer 1

\[\begin{array}{cc}
\phantom{....}\ce{CH3}\\
\phantom{.}|\\
\phantom{.}\ce{CH3-C-OH}\phantom{..}\\
\phantom{.}|\\
\phantom{.}\ce{CH3}
\end{array}\]

Explanation:

An alcohol and Lucas reagent gives two step reaction. In first step carbocation is formed and in second step alkyl chloride is formed. Tertiary carbocation is more stable than primary and secondary so lucas reagent reacts instantaneously with tertiary alcohol.