Which reaction converts an alkene to a diol-alkane?

The reaction that effectively converts an alkene to a diol-alkane is through an oxidation reaction with potassium permanganate (KMnO4). This reaction is known as syn-dihydroxylation, where KMnO4 adds two hydroxyl (–OH) groups across the double bond of the alkene.

In this process, the alkene undergoes a transition through a cyclic manganate intermediate, facilitating the addition of hydroxyl groups to the same side of the double bond, resulting in a vicinal diol. The end product is a diol-alkane, which contains two alcohol functional groups on adjacent carbon atoms.

This method is notable for its ability to selectively oxidize alkenes without affecting other functional groups that may be present in the molecule. It showcases how specific reagents can lead to desired structural changes in organic compounds.

In contrast to the other options: using hydrogen in the presence of a metal catalyst typically leads to hydrogenation, which results in alkanes, not diols. Addition reactions with Hx produce haloalkanes rather than diols, as they add halogen atoms instead of hydroxyl groups. Substitution reactions with NH3 generally replace halogens or other substituents