How many equivalents of `CH_3MgBr` are required to convert ethylethanoate to 2-methyl propan-2-ol?

Answer

To determine how many equivalents of `CH₃MgBr` (methylmagnesium bromide) are required to convert ethyl ethanoate (also known as ethyl acetate) to 2-methylpropan-2-ol, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants and Products**:
- The reactant is ethyl ethanoate (CH₃COOCH₂CH₃).
- The desired product is 2-methylpropan-2-ol (tert-butyl alcohol, (CH₃)₃COH).

2. **Understand the Role of Grignard Reagent**:
- `CH₃MgBr` is a Grignard reagent that acts as a nucleophile. It can react with carbonyl compounds to form alcohols.

3. **First Reaction with Ethyl Ethanoate**:
- Ethyl ethanoate has a carbonyl group (C=O). The nucleophilic carbon in `CH₃MgBr` attacks the carbonyl carbon of ethyl ethanoate.
- This forms a tetrahedral intermediate, where the ethoxy group (C₂H₅O⁻) leaves, resulting in the formation of a ketone (propan-2-one or acetone, CH₃C(=O)CH₃).
- **Moles of Grignard used**: 1 equivalent of `CH₃MgBr` is consumed in this step.

4. **Second Reaction with the Ketone**:
- The ketone (propan-2-one) formed in the previous step now reacts with another equivalent of `CH₃MgBr`.
- The nucleophilic attack occurs again at the carbonyl carbon of the ketone, leading to another tetrahedral intermediate.
- After the workup (typically involving hydrolysis), this results in the formation of 2-methylpropan-2-ol.
- **Moles of Grignard used**: 1 equivalent of `CH₃MgBr` is consumed in this step as well.

5. **Total Equivalents of Grignard Reagent**:
- Since 1 equivalent of `CH₃MgBr` is used for the reaction with ethyl ethanoate and another equivalent is used for the reaction with the ketone, the total number of equivalents required is:
\[ 1 \text{ (for ethyl ethanoate)} + 1 \text{ (for ketone)} = 2 \text{ equivalents} \]

### Final Answer:
**2 equivalents of `CH₃MgBr` are required to convert ethyl ethanoate to 2-methylpropan-2-ol.**