The Grignard reagent required to prepare 2-butanol from acetaldehyde is

Options

A. `CH_(3)MgBr`
B. `CH_(3)overset(CH_(3))overset(|)(C)HMgBr`
C. `CH_(3)CH_(2)MgBr`
D. `CH_(3)MgCl`

Explanation

To determine the Grignard reagent required to prepare 2-butanol from acetaldehyde, we can follow these steps:

### Step 1: Identify the structure of acetaldehyde
Acetaldehyde has the chemical formula \( \text{C}_2\text{H}_4\text{O} \) and its structure can be represented as:
\[ \text{CH}_3\text{CHO} \]
This means it has a methyl group (\( \text{CH}_3 \)) attached to a carbonyl group (aldehyde).

### Step 2: Determine the target product, 2-butanol
2-butanol has the chemical formula \( \text{C}_4\text{H}_{10}\text{O} \) and its structure is:
\[ \text{CH}_3\text{CH(OH)}\text{CH}_2\text{CH}_3 \]
This indicates that 2-butanol has a hydroxyl group (\( \text{OH} \)) on the second carbon of a four-carbon chain.

### Step 3: Understand the reaction mechanism
The Grignard reagent is generally represented as \( \text{R-MgX} \), where \( \text{R} \) is an alkyl or aryl group, \( \text{Mg} \) is magnesium, and \( \text{X} \) is a halogen (like Cl, Br, or I). In this case, we need to add a carbon chain to the acetaldehyde to form 2-butanol.

### Step 4: Determine the appropriate Grignard reagent
To convert acetaldehyde to 2-butanol, we need to add a two-carbon chain to the carbonyl carbon of acetaldehyde. The appropriate Grignard reagent would be ethyl magnesium bromide (\( \text{C}_2\text{H}_5\text{MgBr} \)), which can be represented as:
\[ \text{C}_2\text{H}_5\text{MgX} \]
Here, \( \text{R} \) is \( \text{C}_2\text{H}_5 \) (ethyl group).

### Step 5: Write the overall reaction
When ethyl magnesium bromide reacts with acetaldehyde, the nucleophilic ethyl group attacks the carbonyl carbon of acetaldehyde, leading to the formation of an intermediate alcohol, which upon hydrolysis yields 2-butanol:
\[ \text{CH}_3\text{CHO} + \text{C}_2\text{H}_5\text{MgBr} \rightarrow \text{CH}_3\text{CH(OH)}\text{CH}_2\text{CH}_3 + \text{Mg(OH)Br} \]

### Conclusion
Thus, the Grignard reagent required to prepare 2-butanol from acetaldehyde is:
\[ \text{C}_2\text{H}_5\text{MgX} \]