Identify the product in the reaction `PhC-=CMe overset(H_3O^(+),Hg^(2+)?)rarr`

Options

A. `PhCOCH_2CH_3`
B. `PhCH_2CH_2CHO`
C. `PhCOCOMe`
D. `PhCH_2COCH_3`

Answer

To solve the problem, we need to identify the product formed when phenylacetylene (PhC≡CMe) reacts with mercuric ion (Hg²⁺) in the presence of hydronium ion (H₃O⁺). This reaction involves the addition of water across the triple bond, leading to the formation of a ketone.

### Step-by-Step Solution:

1. **Identify the Starting Material:**
- The starting material is phenylacetylene, represented as PhC≡CMe, where Ph is the phenyl group (C₆H₅) and C≡C indicates a triple bond between carbon atoms.

2. **Understand the Reaction Conditions:**
- The reaction occurs in the presence of H₃O⁺ (acidic conditions) and Hg²⁺ (mercuric ion), which acts as a mild oxidizing agent.

3. **Reaction Mechanism:**
- The triple bond in phenylacetylene undergoes hydroboration-oxidation. The Hg²⁺ ion facilitates the addition of water across the triple bond.
- The reaction proceeds through the formation of a vinyl cation intermediate after the addition of the mercuric ion.

4. **Formation of the Intermediate:**
- The vinyl cation formed will be stabilized by the adjacent phenyl group (Ph). This intermediate can then react with water (from H₃O⁺) to form an enol.

5. **Tautomerization:**
- The enol formed will undergo tautomerization to yield the corresponding ketone. In this case, the enol will convert to a ketone due to the stability of the carbonyl group.

6. **Final Product:**
- The final product after tautomerization will be a ketone, specifically phenyl-2-propanone (PhC(=O)CH₂CH₃).

### Conclusion:
The product of the reaction is **PhC(=O)CH₂CH₃**.