Question

Addition of water to alkynes occurs in acidic medium and in the presence of \[\ce{Hg^{2+}}\] ions as a catalyst. Which of the following products will be formed on addition of water to but-1-yne under these conditions.

Options

• \[\begin{array}{cc}
  \phantom{................}\ce{O}\\
  \phantom{................}||\\
  \ce{CH3 - CH2 - CH2 - C - H}
  \end{array}\]

• \[\begin{array}{cc}
  \phantom{.......}\ce{O}\\
  \phantom{.......}||\\
  \ce{CH3 - CH2 - C - CH3}
  \end{array}\]

• \[\begin{array}{cc}
  \phantom{.}\ce{O}\\
  \phantom{.}||\\
  \ce{CH3 - CH2 - C - OH + CO2}
  \end{array}\]

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

Answer 1

\[\begin{array}{cc}
\phantom{.......}\ce{O}\\
\phantom{.......}||\\
\ce{CH3 - CH2 - C - CH3}
\end{array}\]

Explanation:

\[\begin{array}{cc}
\ce{CH3CH2C ≡ CH + H2O ->[H^-.Hg^{2+}] CH3CH2C = CH2 ⇌ CH3CH2C - CH3}\\
\phantom{...................................}|\phantom{.....................}||\phantom{}\\
\phantom{....................................}\ce{OH}\phantom{..................}\ce{O}\phantom{.}
\end{array}\]