To prepare 3-ethylpentan-3-ol, the reactants needed are

Options

A. `CH_3CH_2MgBr+CH_3COCH_2CH_3`
B. `CH_3MgBr+CH_3CH_2CH_2COCH_2CH_3`
C. `CH_3CH_2MgBr+CH_3CH_2COCH_2CH_3`
D. `CH_3CH_2CH_2MgBr+CH_3COCH_2CH_3`

Answer

To prepare 3-ethylpentan-3-ol, we need to identify the correct reactants. Let's break down the steps to find the reactants required for this synthesis.

### Step-by-Step Solution:

1. **Identify the Structure of 3-Ethylpentan-3-ol**:
- The name indicates that we have a pentane backbone (5 carbon atoms) with an ethyl group (C2H5) attached to the third carbon and a hydroxyl group (OH) also on the third carbon.
- The structure can be represented as follows:
```
CH3
|
CH3-CH2-C-CH2-CH3
|
OH
```

2. **Determine the Carbon Skeleton**:
- The carbon skeleton consists of 5 carbon atoms (pentane). The longest chain is:
```
CH3-CH2-CH-CH2-CH3
```
- The third carbon has both an ethyl group and a hydroxyl group.

3. **Identify the Required Functional Groups**:
- To introduce the ethyl group, we can use an ethyl halide (like ethyl bromide, C2H5Br).
- To introduce the hydroxyl group, we can use a Grignard reagent (like CH3CH2MgBr) that will react with a carbonyl compound to form the alcohol.

4. **Select the Reactants**:
- The Grignard reagent (ethyl magnesium bromide, CH3CH2MgBr) will react with a suitable carbonyl compound to form the desired alcohol.
- The carbonyl compound can be a ketone, specifically 3-pentanone (C5H10O), which has the structure:
```
CH3-CH2-C(=O)-CH2-CH3
```

5. **Write the Reaction**:
- The reaction can be summarized as follows:
- Ethyl magnesium bromide (CH3CH2MgBr) reacts with 3-pentanone (C5H10O) to yield 3-ethylpentan-3-ol after hydrolysis.

### Conclusion:
The reactants needed to prepare 3-ethylpentan-3-ol are:
- Ethyl magnesium bromide (C2H5MgBr)
- 3-pentanone (C5H10O)