During hydration of alkenes, what is the primary catalyst used?

In the hydration of alkenes, phosphoric acid (H3PO4) serves effectively as a catalyst, enhancing the reaction in which water is added across the double bond of the alkene to form an alcohol. This process typically involves the electrophilic addition of a proton (H⁺) from the acid to the alkene, followed by the nucleophilic attack of water on the carbocation intermediate that is formed.

H3PO4 is particularly suitable because it provides a strong acidic medium that promotes the formation of the carbocation while remaining in the reaction mixture, facilitating the conversion of the alkene without being consumed in the process.

This catalytic role is crucial, as it ensures that the reaction proceeds efficiently, yielding a higher concentration of the desired alcohol product. Other acids, such as sulfuric acid (H2SO4), could also serve as catalysts but are less commonly noted in certain contexts for hydration compared to H3PO4, primarily due to the more favorable properties of phosphoric acid in specific aqueous conditions.

The preference for H3PO4 in this context highlights the importance of selecting the appropriate catalyst to optimize reaction conditions and outcomes in organic chemistry.