Question

The major product of the addition of water molecule to propyne in the presence of mercuric sulphate and dilute sulphuric acid is

• A. ethanal
• B. 2-propanol
• C. propane
• D. propanone

Answer 1

Answer: (D)

In the presence of $H_{2}S{O}_4$ and $HgS{O}_4$ as a catalyst, $H_{2}O$ adds to triple bond of propyne to form an unstable enol which readily tautomenses to the propanone. Addition occurs according to Markownikoff s rule. $C{H}_3-C\equiv CH+H^{+\delta }-O{H}^{-\delta }\stackrel{HgS{O}_4,H_{2}S{O}_4}{\to }$ $\underset{Enol(unstable)}{\left[C{H}_3-\stackrel{\begin{array}{c}OH\\ |\end{array}}{C}=\stackrel{\begin{array}{c}H\\ |\end{array}}{\mathrm{CH}}\right]}\to \underset{\mathrm{Pr}opanone}{C{H}_3-\stackrel{\begin{array}{c}O\\ ||\end{array}}{C}=C{H}_3}$