Home > Organic Chemistry > Radical Halogenation of Alkenes (Antimarkovnikov)

Is the hydration of phenylacetylene an antimarkovnikov behaviour?

Answer 1

No, the Markovnikov addition of water across the C-C bond is what phenylacetylene's hydration correlates with.

Mercury(II) ions and gold(I) and gold(III) complexes catalyze the hydration.

The overall effect is as though the water adds a Markovnikov addition across the C–C bond, despite the intricate mechanism.

PhC = CH + H⁺ → PhC = CH₂ → PhC(OH) = CH₂ ⇎ PhC(=O)CH₃

The vinyl cation is created by a Markovnikov addition, in which the H⁺ combines with the terminal alkyne carbon (the C atom) to form more hydrogen atoms.

After that, the OH joins the cationic carbon to create an enol.

The more stable ketone, acetophenone, is produced when the enol tautomerizes.

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Answer 2

Emilia Alvarez

No, the hydration of phenylacetylene follows Markovnikov's rule.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.