Is the hydration of phenylacetylene an anti markovnikov behaviour?

Yes, the hydration of phenylacetylene is an example of anti-Markovnikov behavior. In this reaction, phenylacetylene (a terminal alkyne) reacts with water in the presence of a catalyst, typically sulfuric acid (H₂SO₄) and mercuric sulfate (HgSO₄). Instead of following Markovnikov's rule, where the more substituted carbon gets the hydroxyl group, the anti-Markovnikov hydration results in the addition of the -OH group to the less substituted carbon of the alkyne, and the -H group to the more substituted carbon.

For phenylacetylene, this means that the -OH group ends up on the carbon adjacent to the phenyl group, rather than on the carbon that is more substituted. The resulting product is phenylacetaldehyde.