Kucherov's Hydration

$$\begin{aligned}\text{R--C}\equiv\text{CH} + \text{H}_2\text{O} \xrightarrow{1\% \, \text{HgSO}_4, \, 20\% \, \text{H}_2\text{SO}_4} [\text{R--C(OH)=CH}_2] \xrightarrow{\text{Tautomerism}} \text{R--CO--CH}_3\end{aligned}$$

Notation & Key Points:

• Addition of water follows Markovnikov's rule to give an unstable enol intermediate, which rapidly tautomerizes into a carbonyl compound.
• Ethyne ($$\text{HC}\equiv\text{CH}$$) yields acetaldehyde ($$\text{CH}_3\text{CHO}$$).
• All higher terminal alkynes yield methyl ketones ($$\text{R--CO--CH}_3$$).