Give the produst 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 formed when an excess of phenylmagnesium bromide (PhMgBr) reacts with dimethyl carbonate (CH₃OCOOCH₃), we can follow these steps:

### Step 1: Identify the Reactants
- The reactants are phenylmagnesium bromide (PhMgBr) and dimethyl carbonate (CH₃OCOOCH₃).
- PhMgBr is a Grignard reagent, where Ph⁻ acts as a nucleophile.

### Step 2: Nucleophilic Attack
- The nucleophile (Ph⁻) will attack the carbonyl carbon (C=O) of dimethyl carbonate.
- The structure of dimethyl carbonate is:
```
O
||
CH₃-O-C
|
O
/ \
CH₃ CH₃
```
- The carbonyl carbon is electrophilic and will be attacked by the nucleophile.

### Step 3: Formation of the Intermediate
- When Ph⁻ attacks the carbonyl carbon, it forms a tetrahedral intermediate:
```
O
|
CH₃-O-C
|
O
/ \
CH₃ Ph
```
- This intermediate has a negative charge on the oxygen atom.

### Step 4: Protonation
- The negatively charged oxygen can be protonated by the H⁺ from the reaction medium.
- This results in the formation of an alcohol:
```
O
|
CH₃-O-C
|
O
/ \
CH₃ Ph
```

### Step 5: Repeat the Reaction
- Since we have excess PhMgBr, the Ph⁻ can attack again.
- The process will repeat, leading to further nucleophilic attacks on the carbonyl carbon.

### Step 6: Final Product Formation
- After multiple attacks, we will end up with a compound where three phenyl groups are attached to the carbon, and the original dimethyl carbonate structure is transformed.
- The final product will be triphenylmethanol (Ph₃C-OH).

### Final Product
The final product of the reaction is:
- Triphenylmethanol (Ph₃C-OH).

### Summary of the Reaction
1. Ph⁻ attacks the carbonyl carbon of dimethyl carbonate.
2. Formation of a tetrahedral intermediate.
3. Protonation of the intermediate to form a phenolic compound.
4. Repeated nucleophilic attacks lead to the formation of triphenylmethanol.