The hydration of an alkyne involves the addition of water H2O across the triple bond to form an enol, which then tautomerizes to a ketone. The reaction typically requires a catalyst, such as a mercuric ion Hg2+ or a strong acid like sulfuric acid H2SO4 . Here is a step-by-step explanation of the mechanism:1. Protonation of the alkyne: The first step involves the protonation of the alkyne by the acid catalyst. The acid donates a proton H+ to one of the carbon atoms in the triple bond, forming a carbocation and breaking one of the pi bonds. This results in a vinyl carbocation intermediate.2. Nucleophilic attack by water: The positively charged carbocation is now susceptible to nucleophilic attack. A water molecule acts as a nucleophile and attacks the carbocation, forming a bond with the carbon atom. This results in an oxonium ion intermediate.3. Deprotonation: Another water molecule acts as a base and abstracts a proton from the oxonium ion, leading to the formation of an enol intermediate.4. Tautomerization: The enol undergoes keto-enol tautomerization, which involves the migration of a hydrogen atom and the shifting of a double bond. This process converts the enol to a more stable ketone or aldehyde, if the starting alkyne was terminal .5. Catalyst regeneration: If a mercuric ion catalyst was used, the final step involves the reduction of the mercuric ion back to its original state, regenerating the catalyst and completing the reaction.In summary, the hydration of an alkyne involves protonation, nucleophilic attack, deprotonation, tautomerization, and catalyst regeneration. The key intermediates formed during this reaction include the vinyl carbocation, oxonium ion, and enol.