Give the product when an excess of `PhMgBr//H^(+)` reacts with dimethyl carbonate `(CH_(3)OCOOCH_(3))`?

Options

A. `CH_(3)-overset(OH)overset("| ")"CH"-Ph`
B. `CH_(3)-overset(OH)overset("| ")underset(Ph)underset("| ")"C "-Ph`
C. `Ph-overset(OH)overset("| ")underset(Ph)underset("| ")"C "-Ph`
D. `CH_(3)-overset(O)overset(||)C-Ph`

Answer

To determine the product of the reaction between excess phenyl magnesium bromide (PhMgBr) and dimethyl carbonate (CH₃OCOOCH₃), we will follow these steps:

### Step 1: Identify the Reactants
The reactants are:
- Dimethyl carbonate: CH₃OCOOCH₃
- Excess phenyl magnesium bromide: PhMgBr

### Step 2: Understand the Reaction Mechanism
Phenyl magnesium bromide is a Grignard reagent, which acts as a strong nucleophile. It will attack the electrophilic carbonyl carbon in dimethyl carbonate.

### Step 3: First Nucleophilic Attack
When PhMgBr reacts with dimethyl carbonate, the nucleophilic phenyl group (Ph) attacks the carbonyl carbon of the carbonate, leading to the formation of a tetrahedral intermediate. The reaction can be represented as follows:

\[ \text{CH}_3OCOOCH_3 + \text{PhMgBr} \rightarrow \text{CH}_3OCO(Ph)O^-MgBr^+ \]

### Step 4: Protonation
In the presence of acid (H⁺), the alkoxide ion (O⁻) will be protonated, resulting in the formation of a phenyl ester:

\[ \text{CH}_3OCO(Ph)OH \]

### Step 5: Second Nucleophilic Attack
Since we have excess PhMgBr, the phenyl ester can undergo another nucleophilic attack by PhMgBr at the carbonyl carbon of the newly formed phenyl ester:

\[ \text{CH}_3OCO(Ph)OH + \text{PhMgBr} \rightarrow \text{CH}_3OCO(Ph)(Ph)O^-MgBr^+ \]

### Step 6: Protonation Again
Upon protonation, we form a diphenyl ketone:

\[ \text{CH}_3OCO(Ph)(Ph)OH \]

### Step 7: Third Nucleophilic Attack
Again, due to the excess of PhMgBr, the diphenyl ketone can react with another molecule of PhMgBr:

\[ \text{CH}_3OCO(Ph)(Ph)OH + \text{PhMgBr} \rightarrow \text{Ph}_2C(OH)(CH_3)O^-MgBr^+ \]

### Step 8: Final Protonation
Finally, protonation leads to the formation of the final product, which is triphenylmethanol:

\[ \text{Ph}_3C(OH) + \text{MgBr}OCH_3 \]

### Final Product
The final product of the reaction is triphenylmethanol (Ph₃C(OH)).

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